Laser-Assisted Endoscopic Stapedectomy

The LaryngoscopeLippincott Williams & Wilkins, Inc., Philadelphia© 2000 The American Laryngological,Rhinological and Otological Society, Inc.

MOSER AWARD

Laser-Assisted Endoscopic Stapedectomy:A Prospective Study

Dennis S. Poe, MD

Objective: To improve the techniques required toperform a stapedotomy without prosthesis (stapedio-plasty). Study Design: New infrared lasers were eval-uated for potential use in otological surgery in guineapigs. A prospective human trial of 34 primary stapesoperations using the Argon ion laser was performed,with 11 stapedioplasties and 23 conventional stape-dotomies as controls. Methods: Laser–tissue interac-tions were evaluated for temporal bone and liveguinea pig tissues, measuring crater histology andlabyrinthine temperature elevations. Patients under-going stapedioplasty had Argon ion laser cuts withendoscopic assistance made in the anterior crus andfootplate to mobilize the posterior segment of the sta-pes while the anterior portion remained fixed.Results: Diode laser (808-nm) vaporization cratersand temperature elevations in the vestibule weresuitable for clinical use. Overall, stapedioplasty pa-tients’ hearing was improved with air-bone gap clo-sure to a mean of 8.3 dB (SD 6 9.8 dB). Conclusions:Patients with anterior footplate otosclerosis are can-didates for stapedioplasty preserving the annularring and stapes tendon and eliminating prosthesiscomplications. High-resolution small endoscopes,coupled with Argon ion or diode lasers promise toimprove stapes visualization, enhancing the ability toperform minimally invasive surgery on the stapesfootplate. Key Words: Stapedectomy, laser, endoscopy.

Laryngoscope, 110:1–37, 2000

INTRODUCTIONSurgery to improve hearing loss attributable to oto-

spongiosis involving the stapes footplate (commonly re-ferred to as otosclerosis) has had an unusual history al-

ternating between total excision of the stapes andminimal mobilization procedures. Modern small fenestrastapedotomy procedures using the piston type of prosthe-ses have enjoyed a long-standing record of excellent hear-ing results and minimal complications. There remainrisks of complete deafness and vertigo complications. Themost common reason for failure of stapedotomy or stape-dectomy is a complication related to the prosthesis asreported by Silverstein,1 who noted that 63% of revisioncases in that study demonstrated a prosthesis failure.

Mobilization procedures in the past suffered from ahigh refixation rate, since the stapes was generally mobi-lized through the otosclerotic focus.2 Attempts were latermade to perform stapedotomies fracturing through thenormal footplate posterior to the otosclerotic focus in con-junction with a division of the anterior crus.3 These ma-neuvers were technically difficult to perform reproduciblywith the instrumentation of the day, since surgeons of themobilization era lacked today’s improved microscope op-tics, bright halogen light sources, refined instrumenta-tion, micro drills, and laser technology.

There has been recent interest in re-examining thestapes mobilization techniques using modern instrumen-tation in an effort to reduce the risks associated withcurrent stapedotomy and stapedectomy procedures. Thereremains the problem that there are many anatomical vari-ations limiting access to the stapes footplate and anteriorcrus, which cannot be visualized directly in the majority ofcases. Current fiberoptic delivered lasers allow the surgeonto deliver energy to portions of the stapes not even visible tothe operating microscope simply by palpating the structures,but such “blind” maneuvers are less than favorable.

This project was undertaken to determine whetherendoscopic techniques with fiberoptic delivered laserscould be used for direct visualization of the stapes foot-plate and anterior crus during laser exposures. It was in-tended to study the problems that may be encountered usingendoscopic techniques, to examine the available laser op-tions, and to perform an early clinical trial of laser stape-dotomies without prosthesis using endoscopic techniques inpart to examine the feasibility of the technique. An assess-ment was made of the role of endoscopes in facilitating the

Presented as a Candidate’s Thesis to the American Laryngological,Rhinological and Otological Society, Inc.

Recipient of the Harold P. Moser Excellence in Clinical ResearchAward.

From the Department of Otolaryngology, Massachusetts Eye andEar Infirmary; and the Department of Otology and Laryngology, HarvardMedical School, Boston, Massachusetts.

This work was supported by a grant from the Deafness ResearchFoundation. EndoOptiks, Inc. kindly supported the cost of publication ofthis thesis.

Send Correspondence to Dennis S. Poe, MD, Zero Emerson Place,Suite 2C, Boston, MA 02114, U.S.A.

Laryngoscope 110: May 2000 Poe: Laser-Assisted Endoscopic Stapedectomy

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techniques, and various prototypes were studied so thatrecommendation for future designs could be made.

History of Stapes SurgeryExcision of the tympanic membrane and

ossicles. Valsalva4 in 1704 gave the first known descrip-tion of a fixated stapes and suggested that it was the causeof deafness in a patient. Toynbee in 1853 again reportedankylosis of the stapes and described the disease processof otosclerosis,5 but Wilde,6 in that same year, squelchedany thoughts of surgical repair when he stated that theinner ear “is never the seat of a surgical operation andcannot be examined during life.” In 1876, Kessel7 recog-nized that the ossicles played a role in hearing and deaf-ness. He removed the columella from pigeons and thestapes from dogs, monitoring their hearing by whistlingand making other sounds while they sat quietly or slept.He noted that it required approximately 8 days for aneomembrane to cover their oval windows and restoresome hearing. He concluded that removal of the tympanicmembrane, malleus, or incus could be a possible treat-ment for deafness. In 1878, he attended a hearing im-paired patient who fell off a wagon and suddenly couldhear but unfortunately died of the injury.8,9 The patient’stemporal bones showed fractures through the horizontalsemicircular canal. Kessel subsequently performed hori-zontal semicircular canal fractures and excision of thestapes, covering the oval window with a tissue graft, butthe hearing results were disappointing.

The role of the ossicles was poorly understood at theturn of the 19th century, and subsequent attempts athearing restoration focused on excision of the tympanicmembrane and various ossicles as reported by Baracz,10

Lucae,11 and Boucheron.12 Moure13 in 1880 criticizedthese procedures for their high failure rate and unaccept-able rate of complications, but attempts to perfect thetechniques continued. Miot14 in 1890 introduced Lister’ssterile techniques into otology, operating on 200 patientswith an excision of the tympanic membrane and mobili-zation of the stapes. He noted that the best results didoccur if the bony ankylosis of the stapes was in an earlystage, and the procedure was useless for advanced stages.Blake15 in 1892 introduced the hearing restoration proce-dures to the United States and was the first to use theterm “stapedectomy.” He performed 21 procedures, includ-ing 9 complete stapedectomies, 10 procedures in whichonly the crura fractured, and 2 procedures in which thestapes was too immobile to attempt a mobilization orremoval. Vertigo was present in six of the cases. Jack16 in1893 presented 60 cases and noted that the results wereinconsistent, regardless of whether a mobilization or sta-pedectomy was performed. Grunert17 observed pathologi-cal changes in the round window and was one of the firstto recognize that there may be a relationship between theoval and round window and that round window diseasemay negatively impact the results of even well-performedsurgery. Siebenmann18 in 1900 was apparently very in-fluential in abandonment of the stapes operations. Hewrote that the procedures were useless and dangerous,causing cases of fatal meningitis, and that most hearingresults were only temporary secondary to refixation or

closure of any fenestrae. Hillel,19 in a very nice descriptionof the early history, discussed the reasons for the aban-donment of stapes surgery at that time. He noted that thelight sources were quite primitive and that most surgeonsused a Lucae reflector, which appeared to be like a modernhead mirror but was held in the surgeon’s teeth duringsurgery. There was no standardized audiometry and therewere no masking techniques, so many patients probablydid not have otosclerosis. There was also a severe lack ofunderstanding of the middle ear transformer mechanism,as noted by the common practice of completely removingthe tympanic membrane, malleus, and incus.

Fenestration surgery. In 1897, Passow made a win-dow in the promontory, covered it with periosteum, andnoticed at least a temporary improvement in hearing.20

Thus was born the fenestration era. Floderus21 in 1899made what he called a “sound fistula” in the lateral semi-circular canal and noted a temporary improvement in thepatient’s hearing. Jenkins22 in 1913 also created a windowin the horizontal canal with a temporary hearing improve-ment. Holmgren23 in 1923 has been credited with popu-larizing the concept of lateral semicircular canal fenestra-tion. He was the first to describe performing otologicalsurgery with a 10-power microscope and a rotating burrdrill, beginning the era of otological microsurgery. Heperformed a window initially between the oval and roundwindow and also mobilized the stapes in one patient,achieving very good results. He then performed lateralsemicircular canal fenestrations and presented his earlyseries in 1937.24 Sourdille25 in 1924 presented a multi-staged operation for creating a window in the horizontalsemicircular canal. The first stage was a mastoidectomy,which was followed by a second-stage external auditorycanal skin flap. Once this had healed, the third stage wasperformed: a lateral semicircular canal fistula that wascovered by the skin flap. He later reduced this to a two-stage operation. His procedure remained the standardapproach until Lempert26,27 in 1938 introduced a single-stage endaural fenestration procedure, which he per-formed using a head lamp, magnifying loops, and a dentaldrill. He also had problems with bony closure of the win-dow occurring in 35% of the patients during the first 6months. There was a 2% incidence of complication includ-ing labyrinthine injury, infection, meningitis, and facialparalysis. He noticed that removal of the incus often im-proved his results and that the fenestration worked betterwhen placed over the ampullated end of the lateral semi-circular canal. Dr. Howard House8 has written a wonder-ful history of otosclerosis surgery and described how hestudied Lempert’s technique and refined it with a “doubleblue line” technique. The canal was thinned to create anisland of bone overlying the ampullated end that could beflicked off the canal more easily than the eggshell frag-ments of the previous techniques. Shambaugh8 furtherrefined the technique, introducing constant irrigation dur-ing the fenestration drilling. Experienced fenestrationsurgeons by the early 1950s were reporting 80% to 85%success rates.29

Stapes mobilization. In 1952, Rosen30 startledotologists with a reintroduction of the mobilization con-cept. He had intended to describe the importance of stapes


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palpation before fenestration procedures because, if mobi-lized, the results were less successful as a result of peril-ymph wave cancellation. One patient, before fenestration,had such a palpation, which mobilized his stapes andproduced a dramatic intraoperative improvement in hear-ing and no apparent complications. By this time, the me-chanics of the middle ear transformer were far betterunderstood and preservation of the tympanic membraneand ossicular chain were of paramount concern. Rosenproceeded with five additional patients, mobilizing thestapes, and presented his successful results in 1953, re-ceiving heavy criticism.30 He also introduced curettage ofthe scutum to improve exposure of the stapes before themobilization procedure. The results seemed promising,and many otologists began using the technique immedi-ately. Rosen first described mobilization by pressing onthe stapes neck, indirectly mobilizing the footplate. Asexperience was gained with the technique, he and otherauthors reported a success rate of approximately 30% to35%, with failures being due to disruption of the incudo-stapedial joint (ISJ) or fractures of the crura.29,31,32

Attention began to be directed further down the sta-pes, exploring the possibilities of crura manipulation ordivision and, ultimately, direct manipulation of the stapesfootplate. Herrman33,34 pioneered the delicate, precisechisel techniques that could be used on the crura or foot-plate. Fowler used these techniques and began performinganterior crurotomies in limited anterior otosclerotic foci.35

He noted that with division of the anterior crus, the stapesfootplate would typically fracture either through the oto-sclerotic focus or along a cleavage plain immediately pos-terior to an anterior focus onto the normally thin footplate.Surgeons using his technique increased their successfulmobilization rates from 30% to between 50% and 60%.Fowler also described a partial crurectomy, removing asegment or all of the anterior crus to prevent a problem ofrefixation of the anterior crus. Holmgren36 also found thata partial anterior crurectomy improved the success ratesover crurotomy and was even more effective when com-bined with intentional footplate fracture not passingthrough the otosclerotic focus. Goodhill29 also found im-proved results with anterior crurectomy and footplatefracture with good hearing results in up to 60% of patientsusing this “direct mobilization” procedure.

Recurrent ankylosis of the mobilized stapes was arecognized problem, and Bellucci and Wolff37 in 1959 re-ported that refixation occurred in up to 60% of patients.Rosen2 presented 340 cases with a 4-year follow-up aftermobilization of thin blue footplates with limited anteriorotosclerosis. By 4 years, only 42% of the cases maintainedtheir air-bone gap closure and only 32% maintained clo-sure within 10 dB, indicating the high rate of fixation evenwith limited disease when fractures were made throughthe otosclerotic focus. It was clear that footplate fracturesthrough the otosclerotic focus resulted in a high refixationrate. However, if the footplate fracture were made throughthe normal footplate, the results could be lasting, and nospecific studies on that latter group of patients was re-ported. Goodhill29 stated that “more successful long-rangeresults can be obtained if the fracture area does not godirectly through the otosclerotic process but through the

margin between the otosclerotic lesion and the normalfootplate. A sufficient number of excellent results overlong-range periods exists in this latter group to justify itsretention as a valid technique under [special indications]to be utilized with a high degree of safety in the surgeryfor stapedial ankylosis.”

Juers38,39 in 1959 and 1960 presented what he calleda stapedioplasty, excision of the anterior crus, anteriorfootplate, and mobilization of the posterior crus.Goodhill40 has termed this procedure a stapediolysis.Juers later advised separating the posterior crus from theposterior footplate and redirecting the posterior crus strutinto the open anterior vestibule, which was either leftopen or covered with a tissue or gel foam seal. This pro-cedure was termed by Goodhill29 to be a stapedioplastyand became his procedure of choice. At approximately thesame time, Hough41 described a similar procedure in1960, which he called a partial stapedectomy. One hun-dred fifteen patients had the anterior footplate segmentremoved, and 14 had the posterior segment removed. Pa-tients having the anterior segment removed, including aportion of the anterior crus, had the defect in the anteriorfootplate covered with gel foam, allowing the posteriorcrus and footplate to remain intact but mobilized. Bel-lucci42 noted that the anterior half of the footplate was themost common site of footplate fixation by otosclerosis.Tweedle43 and Drury44 recognized a sharp line of demar-cation between the otosclerotic focus on the anterior foot-plate and the normal bone of the footplate. Hagens45

found that the footplate bone adjacent to the otoscleroticfocus usually appeared particularly rarefied, creating a“fracture line” or shallow crevice that could make a goodcleavage plane for mobilization procedures.

Goodhill and Hough have continued to perform sta-pedioplasty procedures. Goodhill and Harris46 have re-ported their work with posterior arch stapedioplasty ex-cising the entire footplate and anterior crus butpreserving the posterior crus. A tragal perichondrial boatwas made to fit the oval window, and the posterior crus fitinto the center of the boat. In 80% of their cases, theypreserved the stapedius tendon, and they noted that 85%of cases presenting for otosclerosis surgery could have asuccessful operation with this technique. Hough and Dy-er47 have noted that revision stapedectomy surgery issuccessful in less than 80% of cases and recommendedthat preservation of the posterior crus is important inreducing complications. They have performed a proceduresimilar to Goodhill and Harris in placing perichondriumover the oval window with repositioning of the posteriorcrus. In follow-up with 1,000 patients undergoing thetechnique, the air-bone gap closed to less than 10 dB in95.7% and overclosure or complete closure in 80.5%.48

There was a decrease in speech discrimination of 10% to19% in 0.3% of patients, and none had greater than 20%decrease in discrimination. A 5-year follow-up of thatgroup with 200 patients49 found a 10% refixation of theposterior crus and recurrence of a 10-dB or greater air-bone gap. Most of the failures responded well to revisionsurgery. Hough concluded that the partial stapedectomytechnique was not indicated for massive obliterative oto-sclerosis, which occurred in 2% in his series. He found it


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advantageous to preserve the posterior crus and ISJ joint,reducing the risk of incus erosion and permitting func-tional and anatomical integration of the posterior cruswith the oval window tissue graft, avoiding prosthesiscomplications. Portmann50 described another partial sta-pedectomy technique with excision of the entire footplatebut preservation of the entire stapes superstructure, lay-ing it on top of a vein graft to cover the window.

There are temporal bone studies which suggest thatfractures of the stapes footplate may heal with a fibrousunion rather than refixate by osseous regeneration. Mey-ers et al.51 presented a 50-year-old man who underwent asuccessful mobilization 7 years before his death. His tem-poral bone showed fibrous union of an otherwise normalfootplate without any osteoneogenesis, despite findings ofextensive otosclerosis at the fissula ante fenestra and alsomuch of the cochlea. Lindsay et al.52 examined the tem-poral bone of a patient who underwent a stapes mobiliza-tion in which the stapes subluxed into the vestibule. Theyfound that the anterior otosclerotic focus had refixed, butthe posterior portion was free of any new bone growth.

Stapedectomy. John J. Shea Jr.53 in 1956 performedthe first modern stapedectomy, removing the entire stapesand replacing it with an artificial nylon stapes fitted fromthe incus down to the oval window, which was covered bya vein graft. There ensued numerous refinements of thetechniques, methods for covering the oval window, andprosthesis types.54–56 The advent of stapedectomy with aprosthesis made the stapes surgery technically more pre-dictable and with a higher rate of success while maintain-ing a low complication rate. It immediately became theprocedure of choice.

Stapedotomy procedures using a small fenestra.Rosen in his original work had noted that occasional pa-tients experienced a fenestration of the oval window with-out mobilization of the stapes and had dramatic hearingimprovements, a phenomenon later studied by Fernandezet al.57 Interest returned to the concept of partial stapesfootplate removal. Moon and Hahn58 found that with apartial removal of the footplate there was a slight im-provement in the hearing in the 2,000- to 8,000-Hz resultsversus conventional stapedectomy. However, Robinson59

found no difference between full and partial removal of thefootplate using a Robinson prosthesis. Experiencemounted with other workers showing a consistent im-provement in high-frequency hearing with small fenestra.Fisch60 in 392 patients clearly found that a small fenestrastapedotomy with a 0.4- or 0.6-mm piston gave equallygood hearing results as a stapedectomy between 500 and2,000 Hz, but better hearing results at 4,000 Hz. Perssonet al.61 also compared stapedotomy and stapedectomy in437 patients, finding better short-term results in theirseries with stapedectomy, but over time, the stapedecto-mies had a greater threshold deterioration, possibly be-cause of a greater tendency for the prosthesis to migrate.In Shea’s summary62 of his 30 years of experience, hefound that his best hearing results occurred with removalof half or less of the footplate.

Laser stapedotomy. Small fenestra techniques ap-peared to be more desirable because of the improvement inhearing in the higher frequencies, particularly 4,000 and

8,000 Hz, compared with conventional stapedectomy.There was also a noticeable difference in reduction ofpostoperative vertigo with small fenestra techniques.However, the technique was difficult because the footplatecould often fracture unpredictably, and many such casesrequired conversion to a total stapedectomy. Interest be-gan to emerge in the laser as a possible tool for precisebone cutting with minimal trauma.

Lasers in otosclerosis surgery. It has been ob-served that most sensorineural hearing loss that occurredin stapedectomy or stapedotomy surgery was secondary tointraoperative trauma to the labyrinth, most commonlyduring footplate manipulation.63–66 A decrease in labyrin-thine injury was noted with the advent of a small fenestrastapedotomy, and workers began to investigate the possi-bility of using lasers in a further effort to reduce labyrin-thine injury.

In 1965, Stahle and Hoberg67,68 published the firstwork involving the use of laser irradiation in otology. Theyemployed a ruby laser on the labyrinth of pigeons anddemonstrated primary thermal ablation of portions of thelabyrinth, but also remote injuries attributable to pre-sumed “ultrasonic” effects within the labyrinth. Similareffects were noted by Kelemen et al.69,70 in 1966 and 1967using ruby and Nd:YAG laser in mouse temporal bones,finding internal temporal bone injury with massive co-chlear duct hemorrhage and injuries to the organ of Cortiand vestibular labyrinth, despite apparently uninjuredoverlying skin and bone. It was concluded that laser irra-diation could have profound effects at depth within tissuesand that great caution would need to be exercised inclinical use.

Sataloff71 in 1967 used the Nd:YAG in situ on humanotosclerotic stapes, but because of the lack of color, hefound that there was very poor absorption of the energy.He applied copper sulfate as a blue dye and was able toproduce discrete lesions on the otosclerotic bone, but cop-per sulfate is known to be ototoxic and would not have anyclinical application. He noted that there was a risk ofinjury to the facial nerve through inadvertent exposure ofthe nerve by laser energy. The risk of this was particularlygreat with the invisible laser wavelengths.

The argon ion laser was studied for potential intral-abyrinthine injury by Stahle et al.,72 who performedguinea pig studies with the argon laser and found it waspossible to destroy the intralabyrinthine neuroepitheliumwithout damage to overlying otic capsule. Wilpizeski etal.73 in 1972 fenestrated the horizontal and posteriorsemicircular canals in eight monkeys with the argon ionlaser. There was intralabyrinthine local fibrous reactionat the irradiation site, but it was surprising that there wasonly a limited decrease in the animals’ vestibular functionand no significant reduction in hearing.

Wilpizeski and Sataloff74 subsequently followed oneof these monkeys over a long term and noted that itmaintained normal vestibular and auditory function.When it was ultimately sacrificed, the local pathologyreport showed the same limited fibrous reaction aroundthe laser site, and they concluded that argon laser lesionscould produce discrete lesions in the temporal bone andmay be satisfactory for human surgery. Sugar et al.75 in


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1974 exposed the cochleas of 24 guinea pigs to argon ionlaser irradiation and again demonstrated that discretelesions could be produced within the cochleas. The striavascularis absorbed the energy most readily, and his-topathological examination of the stria lesions showedquite discrete necrotic lesions surrounded by areas oflesser damage.

Wilpizeski et al.76,77 subsequently evaluated Nd:YAG, argon, and CO2 lasers in squirrel monkeys. Theyperformed myringotomies, partial tympanic membrane ly-sis, ossicular amputation, stapedial tenotomy, stapes cru-rotomy, footplate fenestrations, tympanic neurectomy,and labyrinthotomies noting preoperative and postopera-tive audiograms and vestibular testing. There were onlyminor postoperative reductions in hearing and balancefunction of all of these procedures. They noted that theCO2 laser had some potential with neoplasms and cho-lesteatoma in which the better water absorption of CO2

may prove to be more useful. They subsequently deter-mined the parameters necessary for CO2 laser lesions on24 human temporal bones and noted that with stapedec-tomy it was possible to injure the sacculus. They recom-mended caution in using the CO2 laser for inner ear sur-gery. Lyons et al.78 in 1978 used a CO2 laser on guinea pigtympanic membranes, ossicles, and cochlear otic capsuleswith settings of 0.4 to 30 W and a range of 50 to 100milliseconds with a 1-mm spot size. Histopathological ex-amination demonstrated cochlear lesions even on the low-est settings.

Lasers were first used for otological application inhumans in 1979 by Escudero et al.79 They had previouslyworked with the argon laser in dogs and rabbits. Then,using the power settings for their microscope-mountedargon ion laser, they employed it in seven patients under-going tympanoplasty using the laser to spot-weld the tym-panic membrane graft in place and demonstrating the useof the laser without any complications. Also in 1979,Palva80 became the first to employ the argon laser forotosclerosis surgery, using it for small fenestrations of thefootplates in 126 otosclerosis patients. He concluded thatthe hearing results in the laser group were slightly betterthan patients undergoing mechanical small fenestrationof the footplate.

Perkins81 in 1980 was the first in the United Statesto perform small fenestra stapedotomies using an argonlaser in 11 cases. He had made previous human temporalbone studies with the argon laser that had a fiberopticcable to a microscope mounting with a micromanipulator.Using a 50- to 100-mm spot size with power settings of 0.4to 0.7 W at 100 milliseconds, he created a small rosettefenestra. He postulated that sufficient energy could bedelivered to make the entire fenestra with a single laserburst but cautioned that direct laser exposure through theopen vestibule must be avoided, since water does notabsorb the argon wave length at 488 nm. He believed that,since the beam was focused at the footplate, the signifi-cant divergence of the beam as it entered the labyrinthwould be somewhat protective to the neuroepithelium. Heused the same power settings on 11 patients with a focallength of 160 mm on the microscope. The tendon andposterior crus were lysed with the laser, using a suction to

remove the vapor plume. Then the footplate was eradi-cated over a several-minute period to minimize any ther-mal effects on the labyrinth. He made a circular rosetteand picked out the intact central bone. In one case, thebony disk fell into the vestibule but did not create anycomplications. All of the cases were successful. There wasno incidence of sensorineural hearing loss, and there wasa near-absence of vertigo other than some mild positionaldysequilibrium, in significant contrast to prior experiencewith conventional mechanical footplate dissections. Lim-ited electronystagmograms (ENGs) were performed oneight of the patients on the second postoperative day andshowed no spontaneous nystagmus.

Later in 1980, DiBartolomeo and Ellis82 presented aseries of patients undergoing argon otological proceduresincluding 7 tympanoplasties, 1 keratoma pearl, hemosta-sis in the middle ear, 2 cases of lysis of middle ear adhe-sions, 4 myringotomies with tube placements, 2 excisionsof external auditory canal osteoma, 3 ossicular sculptings,and 10 stapedotomies. One of these cases had a stapedialartery that was divided bloodlessly using the laser. Two ofthe cases had obliterative otosclerosis on the footplate,and the laser was used to “drill out” the footplate, openingthe vestibule without any drill vibration or apparent gen-eration of heat to the labyrinth. Laser impulses were givenover 1-second intervals on the footplate, and the patientswere all under local anesthesia and reported no vertigo.There was no significant sensorineural hearing loss post-operatively in any case. The authors had performed pre-liminary temporal bone work in seven temporal bones todetermine power settings and used a 250-mm focal-lengthargon ion laser with a spot size of 90 mm and 0.1 to 0.3 Wover a 0.1- to 1.0-second duration. They concluded that itwas a useful technique and had great promise in facilitat-ing stapes surgery and reducing complications. Theynoted that the argon laser was particularly good for he-mostasis during stapedotomy and would most likely proveuseful in hemangioma, telangiectasia, and tattoo removal.

The CO2 laser was investigated for otological surgeryby Lima and Wilpizeski83 in 1980, who performed tym-panic neurectomies in several squirrel monkeys with theCO2 laser. They demonstrated no sensorineural hearingloss either on auditory brainstem evoked response (ABR)testing or with behavioral auditory testing. They con-cluded that the CO2 could be used without significantcochlear effects.

These early works launched tremendous controver-sies over the optimal type of laser that should be used inotological surgery, and for what purposes. DiBartolomeo84

next compared argon and CO2 lasers for otolaryngologicaluses. He found the CO2 laser to be useful in neuro-otological soft tissue, but the argon had significant advan-tages, since it used a visible beam and had a smaller spotsize. He noted that the wavelength of the argon laserallowed passage through the labyrinth and postulatedthat this could be protective to the labyrinth as opposed tothe CO2 laser, which was predicted to risk boiling peril-ymph on exposure to an open vestibule. Wilpizeski85 dis-agreed with these concepts and believed the CO2 could beuseful and safe in otological surgery.


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Epley86 began using the CO2 laser initially in ca-daver specimens on the tympanic membrane and deter-mined appropriate settings of 1 to 2 W on continuous-wavemode with a spot size of 1.5 mm and a 300-mm focallength. He then removed superficial lesions from the tym-panic membrane in 10 patients. He described a slow move-ment in the continuous-beam CO2 laser over the targetuntil char had developed. He manually removed the charand found that there were no instances of tympanic mem-brane perforations. He concluded that the CO2 laser withvery well-controlled techniques could produce excellenthemostasis and ablation of lesions with very controlleddepth of thermal injury. Williams et al.87 used the CO2

laser to perform myringotomies and middle ear lesions infour cats. The settings were 8 W over 50 milliseconds.Histopathological examination and scanning electron mi-croscopy did not demonstrate any injury to the cochlea,and the authors concluded that the CO2 laser could, in-deed, be safe for middle ear use.

The argon laser was used by Glasscock et al.88 inacoustic neuroma surgery using settings of 3 to 3.5 W, 0.1second, with a 250-mm focal length. He noted significantpractical problems using the microscope-mounted micro-manipulator delivery system. It increased the workingdistance of the operating microscope because of the laserattachments and decreased the available light because ofthe micromanipulator beam splitter. The recommendedtechniques of bouncing the laser beam off mirrors to reachotherwise inaccessible locations was quite impractical anddifficult to perform. One of the surgeon’s hands had to beremoved from the operating field simply to operate thejoystick of the manipulator, and there was such relativemovement of the patient versus the microspot that underhigh power, the laser application may require synchroniz-ing with the patient’s ventilations. The authors concludedthat, although the laser was an important advance, therewere definite technological obstacles to be overcome.

Vollrath and Schriener89 carefully examined the ef-fects of the argon laser on the labyrinths of guinea pigs.They used a 488-nm argon ion laser that was microscopebased with a spot size of 150 mm in a guinea pig model.Thermocouples were placed into the second coil of thecochlea or into the round window. Reproducible bone per-forations in the cochleas required energy settings of ap-proximately 2 W and 0.5 seconds. They found that thewater content and color of the tissues greatly influencedthe laser absorption. Wet bone did not absorb energy aswell, probably because of a cooling effect. Pigmented tis-sues such as vessels and stria vascularis had increasedlaser absorption. Laser-irradiated tissue could produce awhite ash, which almost completely reflected subsequentlaser energy and eliminated its effects. Exposures on theguinea pig cochleas were then performed, and tempera-ture elevations of 8°C to 10°C were measured. After aperforation was made into the stapes, irradiation into theopen vestibule produced an elevation of perilymph tem-perature by 10°C as measured at a 2-mm distance. If theprobe were placed immediately beneath the footplate,temperature elevations of 80°C to 100°C degrees wererecorded! It required about 40 seconds between each laserimpact for the temperature to return to baseline.

The effects of laser irradiation on cochlear micro-phonics (CM) and cochlear action potentials were nextinvestigated.90,91 The impact of a single argon laser im-pulse on the stapes footplate produced a decrease or com-plete loss of compound action potential (CAP) for morethan 40 seconds, but the CM was lost for only about 2seconds. The 40 seconds required to restore the CAP co-incided with the time necessary to return the temperatureback to baseline. The researchers also noted that therewas a transient initial response in the CAP to the laserimpact which probably corresponded to the noise of thelaser impact. During the course of these measurements,they noted that a direct current extracochlear potential92

was produced from the laser impulses, which they be-lieved to be due to laser heat injury to the cochlea or bonycochlea. They noted that continued exposure of more than1 second could boil perilymph. As a result of these verywell-conducted studies, they concluded that color, the ab-sorption coefficient of stapes bone, and thickness of thestapes all affect laser-induced endocochlear changesthrough the degree of thermal injury and sound pressureof the laser impact. The laser-induced transients inter-fered with the inner ear function as noted by the transi-tory reduction or complete loss of CM and CAP. Thereforethere was a significant potential for laser injury causingpermanent cochlear damage and sensorineural hearingloss. They measured the sound level of the noise impact atapproximately 80 dB sound pressure level (SPL), and theybelieved that an acoustic shock of this magnitude wasinsufficient to induce significant acoustic trauma. Theyrecommended avoiding direct laser exposure of the peril-ymph and allowing sufficient time between laser impulsesto avoid summating temperatures within the labyrinth.93

Thoma et al.94 made similar sound level recordings inargon laser–exposed temporal bones, noting the soundinjury to be approximately 59 dB SPL.

Injuries with the argon laser were created by Gantzet al.95 in 1982, who performed eight stapedotomies inseven cats using previously determined argon laser set-tings for footplate fenestrae of 1.5 W, 0.1 seconds. Theauthors found that the sacculus was perforated in three ofthe ears, although the maculae remained intact. The rel-ative absence of pigment in the footplate increased thenumber of pulses required for perforations, and they con-cluded that the argon laser still required further investi-gation because of the potential problem of variable absorp-tion of the energy on the footplate depending on colordifferences between individuals.

The pendulum swung back to CO2 lasers, andGoode96 performed preliminary human temporal bone andcat studies with CO2 using settings of 200- to 400-mmfocal length, 1- to 2-mm spot size, 10 to 16 W, at 0.1seconds. He performed laser myringotomies in 11 pa-tients, all without complications, noting that the highwater absorption of the CO2 laser was favorable for thispurpose, since middle ear effusions nicely protected thecochlea. Gardner et al.97,98 used the CO2 laser for acousticneuroma surgery, finding that the tumor mass could berapidly reduced with minimal manipulation and that de-focusing the beam was particularly useful for vaporizingthe tumor. They believed that there was better control of


6

the thermal effects over argon or Nd:YAG lasers. Theyalso performed human temporal bone studies with theCO2 laser on the stapes superstructure and footplate withsettings of 4 to 5 W, 0.05 seconds, and 0.45-mm spot size.Temperature effects in the vestibules were noted, firinginto an open footplate. The vestibule full of fluid had anelevation in temperature of 1°C, but if the vestibule weredry, the temperature elevation was 11°C to 19°C. Theylaser-irradiated the ossicles and footplates of seven catsand found that the histopathological result was limitedonly to the bone itself, with no effects on the membranouslabyrinth. They noted that the facial nerve and footplatecould be easily protected during ossicular surgery by sim-ply covering them with saline or wet cotton. Their conclu-sions were that the CO2 laser probably had fewer risksthan the argon laser because of its high water absorption.

The CO2 laser was not free of potential complications.Coker et al.99 and Thoma et al.100 performed thermalstudies in cats and human temporal bones with the CO2

laser and at higher settings demonstrated thermal injuryto the vestibule, reaffirming the need for caution.

The pendulum continued to swing, and McGee101 in1983 presented 100 patients who had small fenestra sta-pedotomies with an argon laser. He found that the laserhad three functions including vaporizing tissue, cutting oftissue, and coagulation of vessels for improved hemosta-sis. Using the laser, there appeared to be a reduction insurgical trauma with less vertigo postoperatively and adecrease in the length of stay in the hospital. Smallfenestra stapedotomy patients normally required a stay of2 or more days in the hospital versus the laser patients, ofwhom only 27% remained in the hospital 2 or more days.The hearing results between the two groups were compa-rable. He concluded that the laser was effective and safeand that some tasks could be performed with the laserwith less trauma that conventional techniques. Hisfollow-up study102 in 1989, with 510 cases of primarystapedotomy, bore out these early conclusions, demon-strating no complications at all related to the laser and achange in hospital stay with the vast majority of proce-dures being performed on an ambulatory basis. He be-lieved that improved hemostasis and reduction in ovalwindow trauma with decreased vertigo were responsiblefor these improved results. Ricci and Mazzoni103 per-formed argon laser irradiation on human temporal bonesusing a microscope-mounted laser with a 165-mm spotsize, 0.05-second pulse duration, at 0.4 to 0.6 W and notedthe increase in temperature within the vestibules to bewithin 3.5°C using single shots. The authors noted that itrequired about 30 seconds to return the temperatures tobaseline, confirming some of the work previously per-formed by Vollrath. The authors described the 3.5°C tem-perature elevation as “modest” and unlikely to be of clin-ical significance. In the mid 1980s, the potassium titanylphosphate (KTP) laser came into clinical use and wasnoted to have effects similar to the argon laser because ofits very close wavelength.104

Lesinski and Palmer105 decided to confront theswinging pendulum and undertook an in-depth compara-tive study of argon ion, KTP, and CO2 lasers in otology.They performed temperature measurements in the vesti-

bule using a paraffin model of the vestibule with humancadaver stapes placed in the model’s oval window. First,argon 514-nm and KTP 532-nm, both microscope-mountedwith a micromanipulator, were compared. Settings of 2 Wwith a spot size of 50 to 500 mm were evaluated with0.1-second pulse duration. They performed rosettes on thefootplates using overlapping laser burns and nonoverlap-ping laser burns. If there was no overlapping of the burns,the maximum temperature elevations were 0.4°C usingthe 50-mm spot size. If the spots were overlapped, themaximum temperature elevation was 4.3°C to 6.3°C. Thenthey used a thermocouple that was blackened to ensureenergy absorption by stray laser irradiation, and this wasplaced 2 mm deep to the open footplate in the path of thelaser. The KTP laser was fired into the open vestibule witha 100-mm spot size producing an elevation of temperatureof 21°C, and this was raised to 52°C if the spot size wasreduced to 0.05 mm. Then a fiber-delivered KTP laser wasused with a 0.4-mm-diameter fiberoptic probe placed atthe opening of the footplate and therefore 2 mm distantfrom the black thermocouple. Temperature elevation wasnoted to be 12.9°C. It was noted that the fiber was notcollimated compared with the collimated beam from themicroscope micromanipulator delivery system, and thefiber was more defocused with a greater angle of diver-gence compared with the microscope. It was noted thatthese temperature elevations would be insufficient tocause vaporization of the membranous labyrinth, al-though the amount of thermal injury was not known,given these transient temperature elevations. The micro-manipulater argon laser trained into the open vestibulewith a 50-mm spot size produced a temperature elevationof 175°C. Later reports106 showed that if the argon wasused with a spot size widened to 200 mm, temperatureelevations through the open vestibule were only 4°C to6°C. The elevations to 175°C prompted great concern andpredictions of dead ears with further use of argon la-sers.107,108

Lesinski and Palmer109 next examined CO2 lasers asan alternative. The CO2 laser (with settings of 0.6-mmspot size, 3.6 W, 0.1-second duration on superpulse set-ting) irradiating the stapes produced an elevation of 0.2°Cto 0.3°C. When the vestibule was opened, the temperatureelevation was only 0.5°C. The authors concluded that ar-gon and KTP lasers could be used safely if careful tech-niques were observed and operation was performed onlyin primary cases. Revision cases had a greater chance ofexposure through an open vestibule, and only CO2 wouldbe recommended for revision surgery.

Histopathological temporal bone specimens havingundergone stapedectomy have demonstrated adhesionsbetween either the prosthesis or the neomembrane in theoval window and the utricle or saccule.110,111 It was con-cluded that the increased risk of sensorineural hearingloss in revision stapedectomy could be due to direct ma-nipulation of the neomembrane rupturing the membra-nous labyrinth. It was hoped that laser techniques couldreduce this problem in revision operations.

Lesinski and Stein112 presented 59 cases of revisionCO2 laser stapedotomy. Two of the 59 patients (3%) hadgreater than 15 dB sensorineural hearing loss at 4,000 Hz,


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and none of 59 patients had greater than 10 dB sensori-neural hearing loss between 500 and 3,000 Hz. It wasconcluded that use of the CO2 laser was helpful for atrau-matic vaporization of adhesions in revision cases withoutcausing any significant caloric effect or injury to the ves-tibular structures. There was no case of significant senso-rineural hearing loss. The same authors presented 153cases of primary stapedotomies performed with a CO2

laser and reported no significant intraoperative or imme-diate postoperative vertigo.113 The “vertigo symptomswere dramatically reduced” compared with standard sta-pedectomy techniques. Seven of the 153 cases showed adecrease greater than 10 dB at 4,000 Hz, and there wereno cases of sensorineural hearing loss greater than 10decibels between 500 and 3,000 Hz.

The controversy over choice of laser was far fromconcluded. Gherini et al.114 and Causse et al.115 re-examined Lesinski’s data to see why the clinical experi-ence with the argon laser did not bear out the early pre-dictions of severe hearing loss attributable to thermalinjury from exposure through the open vestibule. Theexperiments were repeated through a vestibule model us-ing human cadaver stapes and a silver-colored thermocou-ple that was not blackened. The authors thought that useof a blackened thermocouple caused excessive energy ab-sorption that was not physiological. They used a fiber-delivered argon laser with 514 nm delivered with a fiber-optic probe with a 0.2-mm diameter and with powersettings of 2 W and 0.1 seconds, using 10 to 15 seconds’duration between pulses. They found no discernible eleva-tion in temperature at all when the vestibule was filledwith saline duplicating physiological conditions. If thesaline were removed and the fiberoptic laser aimed di-rectly at the thermocouple, temperature elevations ashigh as 85°C were recorded. The temperature of the laserplume reached 80°C but did not affect the thermocouplewithin the vestibule. They calculated the power densitysettings used in Lesinski’s argon laser work to be 101,859W/cm2 versus 6,366 W/cm2 in their study with the fiber-optic probe. They noted that in clinical practice they nor-mally used between 3,183 and 4,775 W/cm2 with 1- to1.5-W settings. They pointed out a number of advantagesin the fiberoptic delivery system. The fiber, because of itshigher divergent beam of 14 degrees, rapidly dissipatesthe power density and therefore is more safe than a fo-cused microspot. The fiber works best within 1 mm of thetarget and reduces risks of inadvertent injury to the facialnerve, membranous labyrinth, or other structures. Theyfound that settings of 1 to 1.5 W were sufficient to vaporizethe thin bone of the stapes, and with these settings therewas no lateral energy dissipated, as could happen fromerrant reflections off a micromanipulator-delivered beam.The fiber probe cannula could be heated with repeateduse, and they recommended waiting between shots to al-low heat dissipation. They noted that the argon wave-length absorbed best in the red pigments and that, byholding the fiberoptic probe slightly off capillaries, it couldbe used for coagulation and to improve hemostasis. Theyconcluded that the fiberoptic system was more clinicallyuseful than CO2 because it delivered the energy moreprecisely to the exact location for intended use with less

risk of harmful errant irradiation. The results seemed tocorrelate with the authors’ combined clinical experience inmore than 2,200 clinical cases of primary and revisionstapedotomies performed with the handheld fiberopticsystem without any incidence of significant sensorineuralhearing loss or permanent facial nerve injury. Similarexperiences were subsequently reported using handheldfiberoptic probes by Gherini et al.116 Silverstein et al.,117

and others.116,118–129 Silverstein did emphasize exercis-ing caution even with argon techniques, noting that onerevision stapedectomy had a speech discrimination de-crease down to 40% and another developed a granuloma inthe tympanic membrane flap that filled the middle ear,spread into the oval window, and created a dead ear. Heconcluded that the laser technology certainly did not re-move the risk of complications in stapes surgery.

Vernick sought to compare the performance of visibleand IR lasers in a clinical series and performed 100 smallfenestra stapedotomies with two different microscope-mounted lasers. The KTP laser was used in 52 cases, andthe CO2 in 48 cases. He found no difference in the resultsbetween the two and concluded that the laser improvesthe surgeon’s footplate techniques. He also cautioned thatit should not be assumed that there would be a decreasedrisk for sensorineural hearing loss in occasional or resi-dent surgeons simply because the technique was easier.He cautioned that the choice of laser should be based onone’s personal training and laser availability and that thechoice of wavelength was a less significant issue.

Stapes conservation techniques in otosclerosissurgery. Many authors have written about techniques topreserve portions of the stapes and stapes tendon duringstapedotomy surgery, but the benefits of such techniqueshave not been universally accepted.46,47,130

There has been considerable debate concerning theimportance of the stapedius tendon and the loss of func-tion that may occur with its division. Møller131 has dem-onstrated that acoustic reflexes produce hearing attenua-tions of 10 dB for stimulus frequencies below 1,000 Hzwith little effect at higher frequencies. Based on thoseearly observations, it has been thought that the benefitscreated by stapes tendon function may be of minimalresidual importance. More recent studies, however, havecalled this concept into question. Colletti et al.132 per-formed stapedectomies in 362 cases, stapedotomy withlysis of the stapedius tendon in 236, and small fenestrastapedotomy with stapedius tendon preservation in 207.They found that there was no difference in the hearingresults from 500 to 2,000 Hz. There were improved hear-ing results in the stapedotomy patients of both groups at4,000 and 8,000 Hz compared with stapedectomy. Im-provement in hearing at 8,000 Hz occurred only in thestapedotomy groups. The patients in whom the stapediustendon was preserved demonstrated a better speech dis-crimination in background noise, and the noise maskingeffects were even worse in the stapedectomy group com-pared with the group having stapedotomy without tendonpreservation. Complications included dizziness, cochlearloss, slipped prosthesis, incus necrosis, and fixed footplate.The incidence of complications was lower in the stape-dotomy group versus the stapedectomy group.


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The exact role of the stapedius muscle and tendonremains uncertain. Von Békésy133 made observations ofthe stapedius tendon and its effects on movement of thestapes footplate. He noted that the tendon pulled thestapes posteriorly, anchoring the footplate against theposterior annular rim and causing the stapes to tiltaround the fixed posterior rim. He postulated that acous-tic movement of the stapes might involve similar rotationabout the posterior rim. Vlaming and Feenstra,134 withlaser doppler analyses of fresh human cadaver stapes,found that the stapes had a more true piston-like move-ment, rather than tilting about a posterior axis, and raisedthe question as to the role of the stapes tendon in creatinga different axis of stapes motion. Pang and Peake135 an-alyzed stapes movements in 17 cats with the tensor ten-don divided and with acoustic reflex actions blocked byanesthesia. The authors maximally stimulated the stape-dius muscle with alternating currents for more than 30seconds, measured ossicular chain displacements withstimulation levels of 100 to 10,000 Hz at 65 to 85 dB SPL,and measured the cochlear potentials. They found that thestapedius contraction increased the stapes impedance byeffectively increased mechanical strain on the annularligament. They noted that the modest attenuations insound transmission documented in prior studies elicitingthe acoustic reflex may have been limited to submaximalstimulations. Conceivably, the brain could cause muchstronger contractions, as seen in their study using directelectrical stimulation. They further noted that contractionof the stapedius tendon produced motion only of the stapesand not of the incus or malleus. Similarly, tensor tympanistimulation produced only movement of the malleus, notof the incus or stapes. Therefore the brain could be capableof independently contracting these muscles for purposesthat could modulate sound perception, or they could becontracted together in maximal efforts to produce fargreater effects on increasing the impedance of the middleear transformer than had been previously appreciated.

Causse et al.115 have reconstructed the stapediustendon with a specially designed prosthesis which theyused in over 3,400 patients. They found that the hearingresults for word discrimination were better in backgroundnoise than in patients without tendon reconstruction, andthe effects were particularly noticeable in the high-frequency hearing perception. There was also a subjectivereport of decreased hyperacusis compared with prior pa-tients. Causse et al. noted that the stapes tendon can beobserved to contract even when patients speak and is mostlikely important in modulating sound perception in back-ground noise, which would be consistent with the obser-vations of Pang and Peake. Causse et al. believed thatprotection against acoustic trauma is primarily the func-tion of the annular ligament.

Dr. Loren Bartels suggested that laser techniquescould be used to perform an anterior crurotomy and divi-sion of the stapes footplate to eliminate a prosthesis insome cases (personal communication, 1994).

In 1997, Silverstein1 presented his early clinical ex-perience using laser stapedotomy techniques without useof a prosthesis to maximize stapedial function. All caseshad minimal otosclerosis and were performed using the

handheld, fiber-delivered argon laser. He described bend-ing the laser tip to a 30-degree angle to vaporize theanterior crus, which often had to be performed blindlyunderneath the incus. The scutum usually required morecurettage than is customary for stapedotomy to manipu-late the bent fiber between the crura, to adequately reachthe anterior crus. He used a 1.5-mm right-angle pick topalpably confirm that the crus was divided, if it could notbe directly visualized. Then the laser was used on thinblue footplates dividing between the anterior and middleone-third of the footplate. Small picks were used to ensurethat there was complete transection of the footplate andthat the posterior segment of the footplate had been mo-bilized. There was a separation of approximately 0.5 mmbetween the two segments, and fat was placed over theseparation to prevent fistula. If the cases were not ade-quately mobilized, they were converted to a stapedotomy,creating a Rosette and inserting a prosthesis in a conven-tional fashion. The stapes capitulum was preserved when-ever possible, leaving its tendon attachment in an attemptto preserve stapedial tendon function. The indications forthis procedure were otosclerosis limited to the anteriorfootplate and a blue stapes footplate. He cautioned thatthe surgeon must be prepared to perform an ordinarystapedotomy with prosthesis insertion. If the posteriorsegment was adequately mobilized, results showed an av-erage air-bone gap closure to 2.6 dB that remained at 2.4dB after 1 year. There was no change in speech discrimi-nation in any patient, and there were no complaints ofhyperacusis subjectively in the group. Two patients hadinadvertent fracture of the posterior crus during the pro-cedure and had conversion to pistons. He noted that thestapedotomy without prosthesis procedure could be per-formed successfully in 38% of cases undertaken for oto-sclerosis surgery. He thought that with better techniques,as many as 45% to 50% of otosclerosis patients could becandidates. He concluded that the advantages of the sta-pedotomy minus prosthesis procedure were preservationof the tendon with an improvement in hearing, betterspeech discrimination in background noise, and reductionin hyperacusis. There could be no prosthesis complica-tions; therefore it was providing a minimal operation forminimal disease preserving the majority of the naturalstapes function. He believed that possible benefits couldinclude, with increased experience, a reduction in lengthof procedure, reduction in risk for inner ear injuries, anddecreased risks in the face of barotrauma, particularly inscuba divers.

It would appear that today the concept of stapessurgery has returned to the original procedures in whichthe stapes itself could be merely mobilized, but technolog-ical advancements have made the procedures easier toperform and with more predictable and reliable satisfac-tory results, with a dramatic decrease in the incidence ofmorbidity. These achievements have been gained throughbetter understanding of inner ear and middle ear physi-ology and with the development of improved techniques,precise laser technology, and the concepts of small fenes-tration or minimally invasive procedures on the stapesfootplate. Today it is known that stapes mobilization alonethrough the otosclerotic focus has a very high incidence of


9

refixation. Theoretically, it was predicted by the stapesmobilization surgeons that division of the stapes footplateposterior to the otosclerotic focus could give indefinitehearing improvement and would not necessarily result inrefixation unless the otosclerotic focus were to continuegrowing. The difficulties encountered in producing theprecise cuts necessary for mobilization of the posteriorstapes segment are a testament that further refinementsin the technology and techniques are needed before suchprocedures can become available for general use. Longer-term follow-up of patients undergoing surgery without aprosthesis are needed to determine the incidence of refix-ation.

The present study was undertaken to improve on thetechniques available to visualize and operate on the sta-pes footplate. Small-diameter endoscopes were studied fortheir ability to improve visualization of the stapes foot-plate and anterior crus.136,137 Alternative laser technolo-gies were also investigated to determine whether theymay prove more useful in otosclerosis surgery.

Investigation of New Lasers for OtosclerosisSurgery

Lesinski and Palmer105 noted that the ideal laser forotosclerosis should have the following properties: 1) pre-cise optics for delivery, 2) a predictable laser–tissue inter-action with both bone and collagen, 3) no penetration ofperilymph, and 4) no heating of perilymph. They notedthat none of the existing lasers had ideal characteristics.Visible lasers had problems with energy absorption thatvaried depending on different tissue colors, problems withthermal scatter, and unlimited penetration through clearwater. The CO2 laser had near-ideal tissue absorptioncharacteristics but was more difficult to use optically be-cause it could only be delivered with a microscope micro-manipulator arrangement. As an invisible laser, it re-quired a coaxial aiming beam that had problems ofinadvertent dissociation from the true laser and chromaticaberration between the CO2 and shorter aiming-beamwavelengths, so it was impossible to focus both the CO2

laser and aiming beam on exactly the same spot. There-fore the authors concluded that visual lasers have optimalcharacteristics for delivery but suboptimal tissue charac-teristics and that the CO2 laser had optimal tissue char-acteristics but suboptimal optical characteristics.

The search for an “ideal” otological laser has beendirected toward development of a laser with good waterabsorption characteristics that could be fiberoptic deliv-ered. Such a laser would enjoy the benefits of the bestaspects of a CO2 and argon or KTP laser. Water absorp-tion is optimal in the IR frequencies, which are also invis-ible. A fiberoptic delivery system would be one possiblesolution for aiming an otherwise invisible laser. To date,CO2 has not been available through a fiberoptic deliverysystem, with the exception of thin hollow metal tubescalled wave guides that are rather rigid and clumsy tomanipulate, or silver halide fibers, which are relativelythick in diameter and extremely toxic to tissues, makingthem unlikely to be useful in surgery. Therefore thesearch has focused on alternative wavelengths for lasers

in the mid-IR range where the water absorption peaks arefavorable.

Pulsed infrared lasers. The emerging lasers in themid-IR region have been pulsed lasers to date. Argon andCO2 are continuous-wave (CW) lasers, and KTP is aQ-switched (chopped) laser. The pulsed lasers work bystorage of large amounts of energy which is suddenlydissipated in a massive release that generates the laseremission in very short bursts. These high-energy burstsrapidly exceed tissue vaporization levels with efficienttissue ablation that reduces the total energy required forablation compared with CW lasers. Pulsed lasers lose lessenergy to adjacent thermal spread, yielding a better qual-ity of perforation with lower lateral thermic effects versesCW lasers. The extremely-high-energy bursts over verybrief time produce a transient plasma explosion with non-linear (out of proportion for the amount of energy) acousticeffects not found in the CW lasers that follow only linearphotothermal properties (increased energy yielding in-creased thermal damage). Many studies have investigatedpulsed lasers because of their highly desirable wave-lengths and excellent bone-cutting characteristics, but theacoustic shock wave has been found to be a potentiallyserious barrier for their use within the ear, particularly onthe ossicular chain or within the labyrinth.

Nonlinear explosive properties of pulsed lasers werestudied by Esenaliev et al.138 measuring the acoustic andshock waves generated by a XeCl (excimer) laser. Theacoustic wave generated by the pulsed heating of irradi-ated tissue caused a pressure wave termed a thermo-optical acoustic wave. The shorter the pulse, the greaterthe acoustic effect, particularly when the duration of thepulse was less than the duration of the stress relaxationtime as the tissue recoiled from each pressure wave. Thepulsed or explosive ejection of tissue ablation productscaused a compression and rarefaction recoil pulse thatpropagated through tissues and could cause significantinjury even at remote distances from the laser pulse. Thevelocity of the pressure wave increased with increasedamplitude of the wave, which in turn was affected byincreased laser energy or shorter pulse duration. All of theacoustic effects caused tissue stresses and generated en-ergy below levels required for tissue ablation, so no sec-ondary vaporization of tissue would be expected to occurbut widespread necrosis could result. Czurko et al.139

measured similar in vivo effects using pulsed holmium(Ho:YAG [2.1-mm]) and Nd:YAG (1.06-mm) lasers. TheHo:YAG was used with pulses of 1.5 J and 200-microsecond durations in rat brains, and the researchersfound that there was a microexplosion at the point of laserimpact and a secondary pressure wave that penetrateddeep through the brain tissue. The result was local andremote compressive tensile, torsional, and sheer forcesexerted on the brain that depended on the direction ofincident beam and its amplitude, frequency, and pulseduration, as well as damping oscillations of the pressurewave which was tissue and bone dependent. The authorsconceded that the rat brain was quite small and that themagnitude of the injuries could not necessarily be extrap-olated to large mammal brains. Nevertheless, they recom-mended that, when pulsed lasers are used clinically, the


10

energy of each pulse should be kept as low as necessaryand the pulse length be made as long as possible. Thenumber of laser pulses should be kept as low as possible tominimize injury.

There has been growing concern about the effect ofthe acoustic pressure waves in the ear causing mechanicaldestruction and auditory impact acoustic injury with po-tential labyrinthine injury and sensorineural hearing loss.Luz140 determined in rhesus monkeys and humans thattemporary and latent threshold shifts can occur with im-pulse noise of 168 dB SPL or greater. The CW lasers havebeen previously noted to have impulse noises under 100dB and lack a significant acoustic shock wave, whichwould most likely account for the favorable results inotosclerosis surgery. However, these levels have not beenadequately studied for the newer pulsed lasers, nor haveadequate histopathological studies been made with in vivoexperiments using pulsed lasers.

Initial interests focused on the Ho:YAG (2.1-mm) la-sers because of their precise bone-removing properties,reasonable soft tissue coagulation, and fiberoptic trans-mission, as noted by Shapshay et al.141,142 and Pfalz etal.143 Bone cutting was suboptimal with the Ho:YAG laserwith significant bone blackening during penetration andconsiderable deposits of residual melted bone along crateredges. In contrast, the erbium (Er:YAG or Er:YSGG [2.94-or 2.79-mm]) laser had the disadvantage of micromanipu-lator delivery but had much cleaner bone-cutting charac-teristics compared with Ho:YAG, which caused boneblackening during penetration.141,143 Nuss et al.144 ob-served favorable linear relationships between the amountof energy delivered and the mass loss above ablationthreshold levels in tissue using mid-IR lasers.

Erbium laser. The erbium laser has subsequentlybeen investigated more closely for ear surgery because ofits clean bone-cutting characteristics and wavelength of 2.9mm lying close to the maximal peak of water absorption (3.00mm) in the visible and IR spectrum. Shah et al.145 examinedthe Er:YSGG (2.79-mm) laser for the possible ossicular sur-gery using a micromanipulator-delivered, microscope-mounted system. Temperature measurements were per-formed with a thermocouple placed in the vestibule of liverats but not in the direct path of the laser. Ten pulses on thestapes footplate produced a 2.0°C elevation in temperature.This was in reasonable comparison to previous work by Li etal.146 demonstrating a 4°C elevation with the erbium laserstriking rat femurs in a saline bath. It was noted that, sinceonly the first pulse sees virgin bony tissue, the secondarypulses arrived impacting tissues of varying water contentand temperature. Water absorption with the erbium laserdecreased as temperature increased. Therefore, increasedcare would be needed when impacting previously exposedsites, since the energy absorption would be decreased. It wasnoted that the erbium laser was capable of very precise bonyablation and very limited collateral damage with much lesschar than either CW or superpulsed CO2 lasers. The erbiumlaser was intensely absorbed by water and collagen and alsoby the bone minerals calcium phosphate and hydroxylapa-tite. The excellent absorption of the laser energy meant themajority of energy was consumed by tissue ablation andejection of debris, leaving minimal residual energy to dissi-

pate into adjacent tissue causing thermic injuries. The er-bium laser was quite effective in division of the stapediusmuscle, tendon, temporalis fascia, and muscle. Hemostasiswas quite limited, since it principally worked by thermalcoagulation of the vessel, not by hemoglobin absorption. Itworked best on small vessels where absorption into the ves-sel walls would allow flattening and coagulation. It wasnoted that there was a loud pop when the laser impacted thebone, indicating a significant acoustic shock phenomenon.The amplitude of the pop could be reduced if the tissues werewet.

The acoustic shock nonlinear effects for the erbiumlasers have been further studied using pressure transduc-ers and optical flash photography. The Er:YSGG laserexposed to an aqueous medium produced vapor channelformation to depths of 1.5 mm that collapsed, creatingtransient bubble formation and a secondary pressurewave.147 The effect summated with multiple pulses.148

The acoustic effects were measured by Pfalz et al.143 usingSPL recording equipment to record laser impact noises onbovine stapes. Sound levels for different lasers were asfollows: Er:YAG (2.94-mm), 133 dB SPL; CO2, 135 dB SPL;and argon, 92 dB SPL. These researchers and others149

thought these were acceptable acoustic levels for clinicaluse. Another study by Li et al.146 using Er:YAG on a ratfemur produced photoacoustic waves between 99 and 121dB; the authors also thought this was within acceptableclinical limits for human surgery.

Sound-level studies of the laser impact have nottaken into account the photomechanical effects of the non-linear acoustic shock wave. The mechanical injury fromthe shock wave could be expected to add to the potentialnoise-induced injury in vivo, particularly if the stapesfootplate were penetrated and the shock wave were di-rectly propagated into the perilymph.

Noise injury from the erbium laser was studied invivo by Varvares et al.,150 who measured CAP auditorythresholds in guinea pigs subjected to Er:YAG (2.94-mm)laser. They performed precise bone cuts on the stapes of 16guinea pigs while monitoring CAP recordings. Pulses of 10to 55 mJ with an average of 20 mJ per pulse were usedwith a power density of 3.9 to 21.6 J/cm2 using a spot sizeof 570 mm with a micromanipulator delivery system.When footplate fenestrations were incomplete, there wereno threshold shifts in the CAP readings. Once a fenestra-tion had occurred, there were 10- to 30-dB hearing lossesbetween 1,000 and 10,000 Hz. If only the otic capsule wereopened over the cochlear promontory, a hearing loss oc-curred only above 20,000 Hz. In comparison, the otic cap-sule over the cochlea was opened with an argon ion laserand showed similar injury above 16,000 Hz. The noisegenerated by laser impulse stress transients was signifi-cantly higher in the perilymph. Bone is 10% to 20% waterand perilymph is nearly pure water, with a 5 to 10 timeshigher absorption of erbium energy per volume creatingmuch greater stress transients because of the rapid waterablation with the pulsed laser effect. These stress tran-sients were probably responsible for organ of Corti injuryboth by acoustic noise-induced injuries and mechanical-to-electrical transducer injuries of the hair cell mecha-nisms. Injury to the high frequencies was consistent with


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this mechanism, since they were the closest to the site ofthe transients lying at the basal turn of the cochlea.

In a contrasting study, Jovanovic et al.151 performedsimilar experiments with the erbium laser on guinea pigcochleas. They used an Er:YSGG laser with 85 mJ perpulse and 36 J/cm2 in 20 guinea pigs and found no changein the CAP when the laser impacted the intact cochlearpromontory bone. After a cochleostomy was made, an ad-ditional 25 laser impacts for a total of 2.1 J continued toshow no change in the CAP but 50 applications (total of 4.2J) showed some variable and partially irreversible CAPchanges. Seventy-five applications (total of 6.3 J) deafenedthe ears. The authors concluded that at the lower numberof applications, which would normally be used for stape-dotomy techniques, the laser should be safe. Unlike thework by Varvares et al., however, these authors did notimpact the ossicular chain or penetrate the stapes foot-plate, which certainly would be expected to have an am-plifying effect on the injury as demonstrated in the previ-ous study confirming hearing loss with similar energylevels.

Jovanovic et al.152 used pulsed laser systems on ca-daver stapes and bovine compact bone platelets to simu-late stapes. They tried the excimer laser (308 nm) butfound very poor ablation rates. Ho:YAG laser was possiblysuitable for stapedectomy, but the Er:YSGG laser had thehighest ablation rate of bone and was deemed to be themost potentially effective for surgical use. The tissue-ablating effects of the pulsed laser systems through pho-tograph ablation permitted precise and controlled stapesfootplate perforations using low energies with reproduc-ible ablation rates. The extent of thermic side effects atthe footplate was reduced compared with pure thermic-acting CW or superpulsed lasers. Temperatures weremeasured in a cuvette covered with a stapes footplatefiring on the footplate. The Er:YSGG laser produced a3.6°C elevation, 2 mm from the footplate, and the CO2

laser, 8.8°C. The authors found that, because of variationsin the thickness of the stapes footplate, the pulsed laserscould not be used without some penetration into the ves-tibule. Therefore there was concern that laser-inducedshock waves could be introduced into the perilymph, in-creasing the danger to the inner ear beyond that of CWlasers. The Er:YSGG laser was calculated to require twoto four times less total energy deposits versus the CO2 laserfor the same laser defect. The erbium laser formed well-shaped, uniform round perforations close to those performedwith CO2 superpulsed lasers153 and microprocessor-controlled rotating mirror systems with CW CO2 lasers.154

Nagel155 proceeded to use the Er:YAG laser in 83patients undergoing various types of ear operations, 32 ofwhich were small fenestra stapedotomies. To make thefenestra, 3 to 8 pulses of 25 mJ were used to create a 0.4-to 0.5-mm perforation. The crura were divided using 5 to11 pulses of 25 mJ each, and the ligament was lysed with5 to 10 pulses. The authors presented data including ahistogram of a change in hearing loss that showed nospecific pattern of loss at 4,000 or 8,000 Hz. A carefulanalysis of the data, however, showed that 8 of the 32patients had a loss of hearing greater than 10 dB at 4,000or 8,000 Hz, therefore meeting the 1995 American Acad-

emy of Otolaryngology–Head and Neck Surgery (AAO-HNS) criteria130 for hearing loss reporting of 33% signif-icant hearing loss. Although the authors concluded thatthere was no significant incidence of hearing loss from thestudy, strict application of the reporting of hearing criteriademonstrates a significant high-frequency hearing lossobserved in this series, and further studies would be rec-ommended before further clinical trials.156

Thulium laser. Bottrill et al.157 examined a pulsedthulium (Tm:YAG [2.01-mm]) laser for potential otologicaluse. It was a flashlamp-pumped, solid-state laser using achromium-sensitized Cr:YAG crystal doped with thuliumions and delivered through a quartz fiber. Fluences were64 to 328 J/cm2 with 700-microsecond durations through a300-mm fiber. The Tm:YAG laser had many similar char-acteristics to the erbium laser but was less precise incutting bone. It created little charring of bone but morethan erbium and less than CO2. Again, the laser producedan audible acoustic shock that was of significant concern.On human cadaver stapes, a dry bone could actually ig-nite, creating a flame with plume that could have disas-trous results intraoperatively, as well as a loud acousticshock. The flame phenomenon never occurred in moist-ened bones, and the acoustic shock was somewhat atten-uated. Using a vestibule model, temperature measure-ments were made, and with a closed footplate a rise of 2°Cwas noted. If the footplate were opened, a rise of 11°C wasobtained. Further work was not pursued because of theloud shock wave and potential for flame.

Diode lasers. There has been recent interest in thenewer semiconductor diode lasers, which are fiber deliv-ered, inexpensive, and available in CW or pulsed modes.However, the clinically available wavelengths between800 and 1000 nm fall between hemoglobin and waterabsorption peaks. To date, they have been useful only forspecifically pigmented tissues such as the ciliary body inthe eye for glaucoma surgery. Early animal work with810-nm diode lasers has found them capable of deep, ex-tensive thermal damage similar to Nd:YAG lasers becauseof poor tissue absorption and therefore unpredictableamounts of reflection or deep absorption with scatter caus-ing widespread thermal injury.158

Endoscopic-Assisted Laser StapedotomyPurpose of study. Recent advances in optical engi-

neering have revolutionized the practice of medicine withthe concept of minimally invasive diagnostic and surgicalprocedures. The specialty of otolaryngology–head andneck surgery has been particularly enhanced by the incor-poration of endoscopic visualization and surgical tech-niques using micro instrumentation and lasers for precisediagnostic or therapeutic effects. The most rapid develop-ments have been in laryngeal, nasal, and sinus surgery.Endoscopic techniques have lagged far behind in otologybecause of the small size of the external auditory canaland the limited bony confines of the middle ear and tem-poral bone necessitating smaller optical devices thanthose required in other fields. Fiberoptic instrumentshave been introduced with suitably small diameters, butthe resolution has been inadequate for anything otherthan gross anatomical observations. Rigid endoscopes, al-


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though larger in diameter, have much finer resolution anddo yield images of sufficient clarity to make diagnostic andsurgical procedures feasible. However, the larger diame-ter of these instruments has severely limited therapeuticoptions to date. More recent advances in optical technol-ogy have yielded fiberoptic bundles with higher resolutionand glass rod endoscopes of smaller diameter, permittinginstruments with working channels to be introduced intorecesses of the temporal bone. Today endoscopes may becoupled with laser fibers to enjoy the same benefits ofprecise cutting, vaporization, and coagulation that havebeen enjoyed in the larynx and nose.

New laser technology has produced low-cost, semi-conductor diode, mid-IR CW lasers that are deliveredthrough fiberoptics. These lasers promise a greater avail-ability of affordable lasers that may have important rolesin the development of minimally invasive otological pro-cedures. Only near-IR wavelengths are currently avail-able with power outputs suitable for clinical use.

The purpose of this study was to investigate some ofthe newer fiberoptic and rigid endoscopic systems, as wellas the latest diode laser systems currently available. Itwas chosen to evaluate these instruments in the context oflaser stapedotomy procedures, since stapedotomy isamong the most demanding and precise operations inotology. The laser has played a demonstrated role in smallfenestra stapedotomy and, most recently, in a reintroduc-tion of stapedotomy without prosthesis techniques. Per-forming the fine cuts necessary to isolate the anteriorfootplate in cases of limited anterior otosclerosis is feasi-ble, but the technique is difficult. The use of an endoscopeto make these cuts could provide a distinct advantage inimproving the ease and precision of the laser burns on theanterior footplate and anterior crus. Improvement in tech-niques could result in expanding the candidate criteria forthe procedure.

Hopkins rod, fiberoptic, and gradient-index (GRIN)lens endoscopes were examined in cadaver temporalbones, animal operations, and patient surgery. Severalnew laser types in the mid-IR region were evaluated forlaser–tissue interactions. The near-IR, 812-nm diode laserwas selected as a forerunner for future diode lasers, toperform stapes burns in guinea pigs. Contact laser probesthat have never been tried in stapes surgery were evalu-ated making stapedotomy cuts in human cadaver tempo-ral bones while recording from thermocouples placed inthe vestibule. Histological examination of contact-tipprobe burns on ossicles was performed. A clinical series ofpatients undergoing stapedotomy without prosthesis us-ing the argon laser with endoscopic assistance is pre-sented in this study.

MATERIALS AND METHODSAnimals used in this study were albino guinea pigs of either

sex, weighing between 350 and 500 g. Protocols were reviewedand approved by the Animal Care Committee at MassachusettsEye and Ear Infirmary, and animals were humanely cared for atall times.

Laser EvaluationsThe lasers that were evaluated for potential use in this

study included holmium (2.1-mm), diode (808-, 812-, and 980-nm),

and thulium CW (2.1-mm) lasers. Each was evaluated in vitro forits effects on water, soft tissue, bone, and blood, and gross obser-vations of the performance were made.

The Ho:YAG (2.1-mm) laser (Laser 1–2-3, Schwartz Electro-Optics, Orlando, FL) was a pulsed, solid-state system deliveredthrough a 300-mm-diameter quartz optical fiber. The outputranged from 0.3 to 1.5 J per pulse, pulse duration 250 microsec-onds, at a repetition rate of 1 to 15 Hz (pulses/second) withfluences up to 21.4 J/cm2.

The diode (AlGaAs [808-nm] and InGaAsP [812-nm]) lasers(Endo Optiks, Little Silver, NJ) were CW, solid-state semiconduc-tor devices delivered through quartz fibers 100 mm in diameter,numerical aperture (NA) 0.22 or 0.37. They were evaluated witha free-standing fiber and with the fiber intrinsically incorporatedinto either a fiberoptic or GRIN endoscope bundled with theillumination and visualization fibers. The entire fiber probe was0.9 mm in outside diameter (OD) including a 100-mm laser fiberNA 0.37 bundled with a 10,000 (10k)-pixel optical endoscope 0.5mm in diameter, as well as illumination fibers. The GRIN probehad an overall OD of 1.2 mm including a 200-mm-diameter laserfiber NA 0.37 bundled with a GRIN lens 0.5 mm in diameter andillumination fibers. The probe was fitted with a coaxial aimingdiode laser (630 nm) and were operated with outputs up to 0.9 W(measured) over a period of 0.1 to 0.5 seconds, yielding fluences of11.5 to 57.3 J/cm2 for the free beam fibers.

The InGaAsP diode laser was also evaluated with contactprobes. The probes were 600-mm-diameter fibers terminatingwith conical tips tapering to 300 or 100 mm (Surgimedics, TheWoodlands, TX) (Fig. 1) and flat tips with 400-mm diameter(CeramOptec, East Longmeadow, MA). Contact laser power set-tings were the same as the free beam fiber settings.

The diode GaAlAs (980-nm) laser (CeramOptec) was a semi-conductor CW device equipped with a quartz fiber delivery usinga 635-nm diode aiming beam. It was capable of outputs up to 50W with pulse durations down to 0.1 seconds and was operatedbetween 1 and 20 W on continuous mode.

The Tm:YAG (2.1-mm) laser (Maxios, Dublin, CA) was adiode-pumped CW device requiring a 208-V power source andwater cooling. Outputs ranged up to 7.8 W (measured) using a600-mm-diameter fiber delivery with duration of 0.5 seconds.Fluences ranged from 3.5 to 10.5 J/cm2.

Each of the lasers was evaluated for its gross interactions onwater, fresh cadaver guinea pig or chicken muscle and bone, andfresh human blood, all at room temperature. Separate burns weremade on each tissue type after painting it with indocyanine green

Fig. 1. Diode laser contact tips (original magnification 3 50). Top,100-mm tip; bottom, 300-mm tip.


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(ICG) dye (Akorn, Inc., Decatur, IL). Subsequent in vitro andanimal in vivo work was performed with the diode 812-nm laserusing the free beam fibers and contact probes.

Laser–Tissue Interactions in Guinea Pig WithDiode Contact Tip

Gross observations of tissue cutting and apparent thermalinjury were made using the 300-mm contact tip on a live guineapig. It was initially anesthetized with sodium pentobarbital (in-traperitoneally [IP], 10 mg/kg) and Innovar-Vet (intramuscularly[IM], 0.33 mL/kg). Tracheotomy was performed, and the head wassecured in a rodent head holder with the body prone. The animal’sbody temperature was maintained by thermostatic control of theoperating chamber ambient air. A new, clean contact probe wasburned into soft tissue several times until reproducible burnsoccurred, then fixed in position with a clamp, bringing it intocontact with the subject tissues under just sufficient tension toslightly indent the tissue or hold it against bone without moving.The laser was then fired at power settings ranging from 0.5 to 0.9W (measured) for pulse durations varying from 0.1 to 0.5 seconds(0.05–0.45 J) and repeated with the wound submerged in saline 1cm deep, holding a plastic open-ended cylinder over the tissue toretain the saline. Tissues exposed included temporalis muscleand fascia, skin of the pinna, and calvarial bone. Gross observa-tions are noted in this report. Specimens were harvested, placedin 10% formalin, then processed into thin sections and stainedwith H&E, and will be the subject of a subsequent report.

The 812-nm diode laser was then used on formalin-preserved human ossicles employing the 100- and 300-mm contactprobes (Fig. 4). Both fibers were burned into soft tissues untilreproducible laser burns occurred. Exposures of 1.0 W (powersetting) varying from 0.1 to 0.5 seconds (0.1–0.5 J) were made ontwo stapes, four incudi, and two malleoli. Specimens were placedin 10% formalin, then processed into thin sections and stainedwith H&E. One stapes was lost in processing. The remainingossicles were studied under the light microscope for depth andwidth of vaporization craters and adjacent thermal injury.

Endoscopic 812-nm Diode Laser StapedioplastyWith Measurement of Vestibular Thermal Effectsin Human Temporal Bones

Stapes footplate fenestrations were made under endoscopicguidance in 10 human cadaver temporal bones using the 812-nmdiode laser delivered with 300- and 100-mm contact tips whiletemperature measurements were made within the vestibule.

Potential endoscopes to be used in the study were evaluatedin the middle ears of a cadaver and live guinea pig and a humanformalin-preserved temporal bone. These were inspected withHopkins rod, 1.9-mm OD, 0- and 30-degree-view-angle endo-scopes (Karl Storz, Culver City, CA), then the10k pixel, 0.9 mmOD fiberoptic endoscope (Endo Optiks, Little Silver, NJ) and theGRIN (0.5-mm lens in an overall package of 1.2 mm OD) endo-scope (Endo Optiks). The size, ease of use, and optical imagingqualities were compared. Images were presented on a Sony Trini-ton 13-inch color video monitor (PVM-1353MD, Sony Corp., To-kyo, Japan). The Hopkins rod endoscopes were fitted with aTelecam head-C video camera head and Dx-cam processor (KarlStorz). The fiberoptic scope used an internal camera in the laserendoscope unit (Uram E2, EndoOptiks, Little Silver, NJ). TheGRIN lens was fitted with a video camera using an Elmo proces-sor (Elmo Corp., Tokyo, Japan). The GRIN endoscope was usedfor imaging in the subsequent human cadaver stapedioplasties.

Temperatures were recorded with a microprocessor digitalthermometer (Omega Engineering, Inc., Stamford, CT) fittedwith a 0.2-mm-diameter, fiber-coated, silver-colored type K ther-mocouple, which was placed into the vestibule through a laby-

rinthotomy drilled through the horizontal semicircular canal orpromontory or from a middle fossa approach opening the medialwall of the vestibule. The thermocouple was secured within 2 mmof the stapes footplate and with the tip centered deep to it, asestimated by the silhouette seen through the footplate. The lab-yrinth was filled with room-temperature normal saline until thesaline level could be seen against the footplate and the labyrinthsealed with bone wax. If a loss of saline occurred, the bone waxseal was opened and saline replaced. The saline level was ob-served before each laser irradiation to ensure that it was stableand would not drop during the exposure.

Under an operating microscope, the 300-mm contact tip wasfirst used in a temporal bone specimen with the incus and stapespreviously removed to determine the optimal power settings andevaluate the thermocouple performance. A thermocouple wasplaced into the open vestibule through a labyrinthectomy ap-proach, and the vestibule filled with saline as described above.Power settings on the laser were 1.0 W and 0.5 and 0.2 seconds(0.5 and 0.2 J) using a clean, fresh tip. Ten laser exposures spaced

Fig. 2. Operative diagram. Segment of stapes anterior crus is lysedby laser exposure.

Fig. 3. Operative diagram. Right-angled pick confirming completeseparation of the anterior crus.


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2 seconds apart were made along the rim of the oval window tosimulate the maximum number of burns that would be expectedfor most laser fenestrations in a typical stapedotomy, while tak-ing temperature measurements at baseline at the end of the 10burns and every 5 seconds until temperature returned to base-line. The contact fiber tip was then “burned-in,” placing it incontact with soft tissue in the specimen and repeatedly firing thelaser until a char stuck onto the tip. The laser exposures wererepeated, and new temperature measurements made. Once aconsistent laser tissue effect was obtained, further trials weremade with the now burned-in fiber.

Endoscopic stapedotomies were performed using the GRINlens endoscope held in the left (nondominant) hand and holdingthe contact tip fiber in the right hand while recording tempera-ture measurements.

The 300-mm contact tip was first used on 10 consecutivetemporal bone specimens with intact stapes, working through thebony ear canal. The entire stapes footplate was inspected endo-scopically, and curettage of the scutum was not necessary. Theanterior crus was divided using the contact probe with lasersettings of 1.0 W and 0.2 seconds. (0.2 J/pulse) performed underdirect endoscopic guidance. The thermocouple was secured, andthe labyrinth filled with saline as described above. Visualizingthe stapes footplate endoscopically, 10 laser burns with settingsof 1.0 W and 0.2 seconds spaced 2 seconds apart were made inadjacent straight lines across the junction of the anterior andmiddle third of each footplate. Overlapping of the burns wasminimized. Measurements of temperature were made at baseline,immediately after the 10 laser burns, then at 5-second-intervalsuntil the temperature returned to baseline. The procedure wasperformed on 10 separate temporal bone specimens.

The 100-mm contact probe was used on five of the previoustemporal bones for similar measurements. The probe was ini-tially adequately “burned-in,” then under endoscopic guidancethe procedures were identically repeated except that a new cutwas made into the anterior crus and the footplate was dividedacross the junction between the posterior and middle thirds.

Clinical Endoscopic-Assisted Argon LaserStapedotomy Without Prosthesis(Stapedioplasty)

Thirty-four consecutive patients underwent primary sur-gery by the author for otosclerosis between December 6, 1996,and February 25, 1998, and were studied prospectively. Eleven ofthese patients (32%) underwent a laser stapedioplasty withoutprosthesis. Patients were given the option of conventional stape-dotomy with prosthesis versus stapedioplasty, and informed con-sent was obtained. Each patient understood that it was uncertainwhether stapedioplasty were possible and that a conventionalprocedure may be performed. They understood that there were nodata available regarding the potential long-term success of thestapedioplasty. All 34 patients planned for primary otosclerosissurgery, and the decision to perform the procedure with or with-out a prosthesis was made intraoperatively. The 23 patients(68%) who had conventional stapedotomies were followed as acontrol group.

Surgical TechniqueEight of the patients underwent general anesthesia, and

three had local anesthesia with intravenous sedation. Lidocaine1% with 1:100,000 epinephrine injection was made in all casesinto the external auditory meatus and posterior tragus. Tragalperichondrium was first harvested for sealing of the oval window.Under the operating microscope, a tympanomeatal flap was ele-vated, working through the external auditory canal and using aspeculum holder. Standard curettage of the scutum was per-formed until the entire footplate, pyramidal eminence, and facialnerve were visible, and the chorda tympani nerve was preservedin all cases. The ossicles were palpated to confirm that the stapeswas fixed. The oval window was inspected for the degree ofotosclerosis. If the otosclerotic focus appeared limited to the an-terior third of the footplate, a stapedioplasty was attempted. Aprototype argon laser endoscope (Endo Optiks) was designed tospecifications of the author and employed for the first four pa-tients. The endoscope was the same as the 10k fiberoptic imagingand laser bundle used in the guinea pig study just described, butfitted with a 200-mm diameter argon laser fiber protruding fromthe endoscope’s distal tip a distance of 3 mm. The imaging wasperformed with an Elmo camera and processor and a Sony 17-inch video monitor. The laser fiber was coupled to the argon laser(HGM, Salt Lake City, UT). Fog-Away antifog solution (TechnolMedical Products, Inc, Fort Worth, TX) was applied to the endo-scope tip. The laser endoscope was introduced into the field,removing the microscope and viewing the field from the monitor.Lysis of a segment of the anterior crus was performed with laserpower settings of 2.0 W and 0.2 seconds using the laser in nearcontact with the bone (Fig. 2). Division of the crus was confirmedvisually or by palpation with a right- angled pick (Fig. 3). Thelaser setting was then reduced to 1.5 W and 0.2 seconds for thestapes footplate. The laser was used to make a row of burns on thefootplate, to separate it at the junction between the anterior andmiddle thirds. Smoke was evacuated during the laser exposureswith a 24-gauge suction held in the author’s nondominant (left)hand. The burns overlapped sufficiently to create a gap approxi-mately one burn wide (0.2 mm) and required between 6 and 10exposures (Fig. 4). Once the footplate division appeared complete,the posterior crus was palpated with the protruding laser fiber toensure that the posterior footplate was mobile. The endoscopewas removed, and the microscope returned. Unrestricted mobilityof the posterior footplate was confirmed by palpating the poste-rior crus with a straight pick (Fig. 5); then the footplate wascovered with small pieces of perichondrium (Fig. 6), and the flapwas closed.

Patients with obvious larger plaques of otosclerosis fixingmore than the anterior third of the footplate, or who had anatomy

Fig. 4. Operative diagram. Row of laser burns made across stapesfootplate to completely separate the anterior one third from theposterior two thirds of the footplate. The cut is made posterior tothe otosclerotic focus, not through the otosclerosis.


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that prevented safe performance of the stapedioplasty technique,underwent a conventional stapedotomy with an argon laser ro-sette in the center of the footplate or drill-out if necessary andinsertion of a prosthesis. The stapedius tendon and posterior cruswere lysed with a standard laser fiber (CeramOptic EndoprobeEP-20, HGM); then additional laser burns were made to create acentral rosette generally in continuity with the first row of burns.The char was removed with oval window picks or rasps, and aSchuknecht fluoroplastic piston 0.6 mm in diameter (Smith &Nephew, Inc., Memphis, TN) was placed through the fenestra.Small pieces of perichondrium were placed around the prosthesisand covered the footplate. The flap was closed.

Attempted stapedioplasty in patients in whom the footplatecould not be adequately mobilized was converted to a conven-tional stapedotomy using the above techniques. The footplatelaser burns were merely expanded to form a central rosette toaccommodate the prosthesis.

The prototype laser endoscope was not available for theremaining six patients, who had the stapedioplasty performedunder the operating microscope with a standard laser fiber. Thefiber tip required a slight bend (performed by hand) to pass itinferiorly to the stapes and contact the anterior crus, placedeither under direct vision or by palpating the crus with the fiber.A segment of the anterior crus was lysed. Complete separation ofthe crus was confirmed by passing a right-angled pick throughthe defect and by visual inspection through a 1.9-mm-OD 30-degree Hopkins rod endoscope (Karl Storz) looking through theeyepiece of the endoscope or using an Elmo camera and Sonymonitor. Laser lysis of the crus under direct endoscopic visual-ization was possible but was difficult because of the relativelylarge endoscope diameter. The footplate burns were made aspreviously described under the operating microscope, and some ofthe burns either at the superior or inferior oval window rim wereperformed without direct visualization because of obscuration bythe remaining stapes superstructure. The entire footplate couldbe visualized endoscopically, but simultaneous laser surgery withthe endoscope in place was impractical. The procedure was com-pleted as described above.

Hearing results were reported in accordance with the rec-ommendations of the AAO-HNS 1995 Committee on Hearing andEquilibrium.130 The pure-tone averages for air and bone conduc-tion were calculated as the mean of the 500-, 1,000-, 2,000-, and3000-Hz frequencies. Preoperative and postoperative data were

compared using the paired Student t test with P value less than.05 used for a level of significance.

RESULTS

Observations of Laser–Tissue InteractionsHolmium laser. The pulsed Ho:YAG (2.1-mm) laser

was characterized by a loud, explosive impact onto allsamples. The acoustic shock was an audible “pop” thatraised concerns about potential hearing injury if used inthe ear. The shock was apparent in water, blood, and freshchicken breast. Impact on bone produced a more dramaticexplosion, which could include a transient flame if a drycharred area were hit. Considerable splatter of tissue andfluid debris resulted from the impacts. The magnitude ofthe acoustic shock and degree of explosive force that re-sulted from energy levels necessary to cut bone were notcompatible with the precise requirements of otologicalsurgery.

Diode lasers. The performance of the two diode Al-GaAs (808-nm) and InGaAsP (812-nm) lasers was nearlyidentical, and no differences in tissue interactions wereobserved between them. There was no difference in thetissue interactions between the free fiber and the endo-scope bundled laser fiber. Measured power outputs wereidentical for both fibers.

Using exposures of 0.9 W (measured), 0.1 to 0.5 sec-onds, no effect was seen on water, fresh human blood, orlight-colored muscle in fresh cadaver guinea pigs. Darkermuscle did absorb some energy, showing a small area ofthermal injury with water vaporization, slight contractionof the impacted area, but no tissue vaporization. Darkdried blood or coagulated blood within vessels absorbedsufficient energy to produce favorable tissue vaporizationeffects. Light-colored bone had no effect, but dark or blood-stained bone absorbed the energy well and showed favor-able punctate vaporizations with minimal surroundingthermal injury zone. If a poorly absorbing tissue under-went repeated laser exposure to produce a small darkchar, the char immediately absorbed the energy, produc-

Fig. 5. Operative diagram. Mobility of the stapes posterior segmentis tested by palpation with a straight pick.

Fig. 6. Operative diagram. Strips of perichondrium have beenplaced over the footplate to seal the vestibule.


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ing a favorable vaporization cavity. Similarly, tissuespainted with ICG dye to enhance absorption showed goodburns with little adjacent thermal injury. The depth ofpenetration was limited unless some degree of char re-sulted from the initial burn of the ICG. The ICG did notuniformly coat the tissue, and thinly dyed areas couldpermit burning off the ICG, causing only superficial ther-mal injury to the underlying tissue without vaporizationor char to aid with subsequent burns. The improved ab-sorption with ICG produced a more vigorous vaporizationin tissue resulting in spatter that contaminated the endo-scope lens and laser fiber tip. Additional laser use withoutremoval of the debris would damage the fiber tip andreduce power.

Continuous-mode laser applications at 0.9 W (mea-sured) on poorly absorbing tissues produced slow, diffuseheating of the water content. When sufficient water hadevaporated, wide charring and incandescence developed.In one case the laser was exposed to a guinea pig stapes insitu. There was little appreciable effect for several sec-onds, then it suddenly and uncontrollably charred theentire superstructure. Using 15-W continuous mode pro-duced an acceleration of the same process with a widerand deeper region of char and burning. It was possible tomore quickly induce a char in poorly absorbing tissues,but the depth and width of the burn were difficult tocontrol.

Diode InGaAsP (812-nm) laser with contactprobes. With the diode InGaAsP (812-nm) laser, contactfibers had good handling characteristics and were easy touse in conjunction with a handheld endoscope if desired.

Flat-tipped, 400-mm probes produced a wide field ofheating that was difficult to control. There was no differ-ence in tissue effects with degree of pigmentation. Atsettings of 1 to 4 W on continuous mode, both bone and softtissue had a radially widening field of coagulation followedby central burning and charring. At 5 W, bone cuttingcould occur but produced a 1-mm-wide thermal injuryzone with charring. When the tissue and probes weresubmerged in water, minimal tissue effects occurred andthe probe was seen to slowly heat the water bath.

The conical tip (300 mm) had much better tissueinteractions than the flat tip and was much more control-lable and predictable. Burns were very favorable withsharp vaporization margins and minimal adjacent ther-mal injury. There was a reduction in absorption of energyin nonpigmented tissues that was overcome by “burning-in” the tip with repeated applications in soft tissue orblood or by painting ICG on the tip. Tissue splatter ontothe probe was inconsequential, since its optical qualitieswere insignificant. Bone-cutting of the ossicles was favor-able but produced a wider zone of thermal injury thandesired. The tissue and probe were submerged in a waterbath and tissue vaporization was still possible with a traceof bubbling seen at the tip and no visible adjacent thermalinjury at settings of 1.0 W and 0.5 to 1.0 seconds.

The 300-mm tip was used on temporalis muscle andfascia, cranial bone, and skin of the pinna in a live anes-thetized guinea pig. Soft tissues had slightly less pigmen-tation than the cadaver preps, and there was a morenoticeable problem with heating of nonpigmented tissues.

A more thorough burn-in was required for reliable func-tioning of the tip. A matrix of burns was performed vary-ing the exposures from 0.5 to 1.0 W over a period of 0.1 to0.5 seconds, then repeated with the tissue submerged in asaline-filled cylinder. Burns with exposures of 0.5 W and0.1 second were minimal, and with exposures of 1.0 Wwith 0.5 seconds, much larger and deeper with a widerzone of adjacent injury. There was a linear expansion ofthe crater and adjacent thermal injury radius with in-creasing power or time of exposure. Saline-submerged tis-sue burns were markedly reduced in depth and width witha much smaller thermal injury zone. Burns on skin andmuscle or fascia were very similar. Bone burns producedmore significant charring within the crater and a widerzone of thermal injury than with soft tissue.

The 100-mm conical tips had more precise burn andcutting properties than the 300-mm tips. The tip was evenless effective on nonpigmented tissues than the 300-mmtip and required a thorough burn-in to work on wet whitebone. The bone and tissue vaporization was very precisewith tight margins of adjacent thermal injury. Cuttingand vaporization on submerged tissues were less effectivethan with the 300-mm tip.

The 300- and 100-mm tips were used on humanformalin-preserved ossicles. The 300-mm fiber burns werewider with a larger zone of adjacent thermal injury thanthe 100-mm fiber burns. The stapes footplate cuts with the100-mm fiber were very precise, and adjacent thermal

Fig. 7. Formalin-preserved human stapes with linear burn madeacross footplate using 100-mm contact tip with 812-nm diode laserpower setting of 1.0 W for 0.2 seconds (original magnification 3 30).


17

injury appeared minimal. Histopathological appearance isdemonstrated in Figures 7 to 9. Results are presented inTable I and in Figures 10 to 12.

Diode GaAlAs (980-nm) laser. With the diodeGaAlAs (980-nm) laser the tissue interactions weregrossly indistinguishable from the 808- and 812-nm la-sers. Absorption in water, nonpigmented tissues, andfresh blood was poor and improved with pigmentationadded, dried blood, or painting with ICG. Operation at 20W and continuous mode produced deep water vaporizationuntil charring began, followed by extensive burning with awide margin of thermal injury.

Thulium laser. With the Tm:YAG (2.1-mm) continuous-wave laser, exposure to water produced rapid boiling at thesurface of the water throughout the exposure. Irradiation offresh human blood produced rapid boiling of the water con-tent superficially followed by charring of the surface, then

deeper vaporization through the char. On cadaver guinea pigtemporalis muscle, settings of 2 W (measured), 0.5 seconds,produced only superficial thermal injury with vaporizationonly of water. Settings of 4 W (measured) produced a favor-able, precise burn with a narrow rim of thermal injury.Settings of 5, 6, and 7.5 W (measured) had increasingly deep,sharp-walled vaporization craters but a wider margin ofthermal injury than at 4 W. The effects on bone were similarwith the optimal crater and minimal adjacent thermal injuryfound with the 4-W exposure. Bone burns showed a tightcrater formation with central charring that appeared veryfavorable for ossicular work. There was no significant audi-ble acoustic shock. The prototype laser became disabled andcould not be used at that time for further study.

Fig. 8. Formalin-preserved human malleus manubrium exposed to300-mm contact tip with 812-nm diode laser power settings of 1.0 Wfor 0.1 seconds (left burn), 0.2 seconds (middle burn), and 0.5seconds (right burn) (original magnification 3 50).

Fig. 9. Formalin-preserved human malleus manubrium exposed to100-mm contact tip with 812-nm diode laser power settings of 1.0 Wfor 0.1 seconds (left burn), 0.2 seconds (middle burn), and 0.5seconds (right burn) (original magnification 3 50).

Fig. 10. Median depths of craters created on human formalin-preserved ossicles with 812-nm contact tip diode laser delivering1.0 W. Medians are calculated from data in Table I.

TABLE I.Dimensions of Contact Laser Tip Burns on Human Ossicles.

Duration (secs) Depth (mm) Width (mm) Injury (mm)

100 mm (n 5 3 ossicles)

0.5 320 185 62

345 120 41

380 245 40

0.2 205 85 8

240 60 18

140 120 7

0.1 125 60 4

120 35 6

85 30 1

300 mm (n 5 3 ossicles)

0.5 485 280 95

440 240 74

420 165 83

0.2 340 180 47

405 165 55

245 280 62

0.1 180 65 4

145 85 38

300 160 9


18

Endoscopic 812-nm Diode Laser StapedioplastyWith Measurement of Vestibule Thermal Effectsin Human Temporal Bones

Contact tip probes were used to perform the footplatestapedioplasty cuts while separately hand-holding theGRIN endoscope for visualization. No curettage of thescutum was necessary in any of the 10 human temporalbone specimens, and each procedure was performedthrough the external canal. The endoscopic view was rea-sonably wide in field and compared favorably to rigid rodmulti-element endoscopes and to a surgical microscopicview. There was slight noticeable loss of resolution and adefinite reduction in brightness compared with Hopkinsrod scopes. Adequate visualization of both stapes cruraand the entire footplate was obtained in each case with theendoscopic view. The laser probe was generally passedfrom the inferior aspect through the crura. It was oftenawkward to maneuver the probe up to the superior rim ofthe footplate through the crura and would have been eas-ier with an angled probe. When possible, the superior-most burns were made passing the laser superior to thesuperstructure.

The contact probes required a thorough burn-in pro-cedure before yielding reproducible burns. Before burn-in,probes used on a practice specimen showed variable ab-

sorption of the energy on the footplate area and a widerange of vestibule temperature elevations, as extreme as50.7°C in one instance. Once the tip was coated with char,it performed very reproducibly. The 300-mm probes had alarger excursion of temperatures than the 100-mm probes.The quality of the burns with the 100-mm probes was veryclean with minimal char and tight, round craters. Tem-perature elevations with 10 serial burns using the 100-mmprobes yielded an average rise of 3.25°C and a maximumrise during the trials of 4.30°C, which are consideredclinically acceptable. Complete data are presented in Ta-bles II and III and summarized in Figures 13 and 14.

Clinical Endoscopic-Assisted Argon LaserStapedotomy Without Prosthesis(Stapedioplasty)

Thirty-four patients underwent primary otosclerosisoperations in the study period. Eleven patients (32.4%)had a stapedioplasty procedure, and the remaining 23(67.6%) had a conventional small fenestra stapedotomy. Inthe stapedioplasty group ages ranged from 32 to 55 yearswith a mean of 42.5 years. There were seven women andfour men, 7 left ears and 4 right. In the stapedotomy groupages ranged from 21 to 79 years with a mean of 45.0 years.There were 14 women and 9 men, 12 left ears and 11 right.

Each case was examined to determine whether astapedioplasty should be attempted. The decision wasbased on adequate exposure of the footplate to make thecuts and extent of otosclerotic involvement. Stapedio-plasty was attempted on 13 patients, but two cases wereconverted to conventional stapedotomy when the footplatecould not be adequately mobilized. The intraoperativefindings and the reasons stapedioplasty could not be per-formed in the 23 stapedotomy patients are summarized inTable IV. Nine of the patients (39%) required a microdrillfenestra because of extensive otosclerosis.

Complete audiometric data for patients are presentedin Tables V through X. The stapedotomy and stapedio-plasty groups contained very similar distributions of hear-ing losses, with the mean preoperative air-bone gapfor stapedioplasty of 26.6 dB (SD 67.30) and for stape-dotomy, 27.6 dB (SD 68.84). The postoperative resultswere statistically similar with mean air-bone gap for

Fig. 11. Median widths of craters created on human formal-preserved ossicles with 812-nm contact tip diode laser delivering1.0 W. Medians are calculated from data in Table I.

Fig. 12. Median zones of thermal injury surrounding craters createdon human formalin-preserved ossicles with 812-nm contact tip di-ode laser delivering 1.0 W. Medians are calculated from data inTable I.

TABLE II.Vestibule Temperatures After 10 Exposures With 300-mm Contact

Laser Probe.

Time (s)Mean 300 mm

(degrees C)Median 300 mm

(degrees C) SD 300 mm

0 6.82 5.65 3.47

5 3.58 3.65 1.52

10 2.55 2.60 1.15

15 1.90 1.90 0.87

20 1.45 1.40 0.65

25 1.15 1.10 0.52

30 0.93 0.85 0.41

35 0.77 0.70 0.35

40 0.67 0.60 0.28


19

stapedioplasty of 8.3 dB (SD 69.8) and for stapedotomy,4.9 dB (SD 63.77) at 6 weeks after surgery. P values forimprovement based on the operation were P 5 .0002 forstapedioplasty and P , .0001 for stapedotomy at 6 weeks.The stapedioplasty results more than 6 months after sur-gery includeda mean air-bone gap of 10.8 dB (SD 69.40),which was not significantly different from the 6-weekresults (P 5 .59). There was no correlation between sever-ity of air-bone gap and ability to perform stapedioplasty.

There were no predictive factors noted on regression anal-ysis.

There was a single patient (patient 2) in the stape-dioplasty group who failed to improve postoperatively.This patient had otosclerosis involving more than the an-terior one-third of the footplate, and the laser division ofthe footplate was made closer to the middle of the foot-plate. It was thought that adequate mobilization of theposterior segment had been achieved. Patient 8 on anearly postoperative audiogram failed to adequately close

Fig. 13. Time decay curve of thermocouple measurements in ves-tibules of human temporal bones subjected to laser exposure of thefootplate with 10 burns separated by 2 seconds each, using the300-mm 812-nm contact tip diode laser delivering 1.0 W at 0.2seconds. Graph shows range of temperatures recorded and plotsmean values.

Fig. 14. Time decay curve of thermocouple measurements in ves-tibules of human temporal bones subjected to laser exposure of thefootplate with 10 burns separated by 2 seconds each, using the100-mm 812-nm contact tip diode laser delivering 1.0 W at 0.2seconds. Graph shows range of temperatures recorded and plotsmean values.

TABLE III.Vestibule Temperatures After 10 Exposures With 100-mm Contact

Laser Probe.

Time (s)Mean 100 mm

(degrees C)Median 100 mm

(degrees C) SD 100 mm

0 3.24 3.60 0.94

5 2.62 3.00 0.68

10 2.14 2.40 0.49

15 1.74 1.90 0.38

20 1.46 1.60 0.34

25 1.18 1.20 0.29

30 0.98 1.00 0.29

35 0.86 0.90 0.27

40 0.72 0.70 0.27

TABLE IV.Intraoperative Findings During Stapedotomy.

PatientNo.

FootplateDrillout

AttemptedStapedio-

plasty Comments

1 Otosclerosis involving both crura

2 Y

3 Large plaque otosclerosis

4 Y Stapes footplate not mobilized

5 Crura fixed to promontory

6 Y

7 Y

8 Y

9 Y Stapes footplate not mobilized

10 Y


12 Narrow oval window & low VIInerve

13 Y

14 Small oval window niche




18 Y

19 Narrow oval window

20 Crura fixed to promontory


22 Y

23 Y


20

the air-bone gap, but she had a severe upper respiratorytract infection at the time, and a middle ear effusion.Subsequent testing demonstrated closure of the gap.There was no significant worsening of the stapedioplastyresults during 6 months of follow-up.

The stapedotomy group had one patient (patient 12)who failed to close the air-bone gap within 10 dB, and thehearing at 8 kHz decreased, but he was tested only 3weeks after surgery and subsequent audiograms were notavailable. The two patients who had stapedioplasty at-tempts converted to stapedotomy had successful outcomeswithout complications.

There were no complications in either the stapedio-plasty or stapedotomy group. The chorda tympani was

preserved in all cases. There was no incidence of signifi-cant sensorineural hearing loss or significant change inspeech discrimination (word recognition) as defined by the1995 AAO-HNS committee.130

DISCUSSIONNew lasers, laser delivery systems, and endoscopic

techniques were investigated to determine whether theseemerging technologies could facilitate the techniques re-quired for stapedotomy without a prosthesis (stapedio-plasty). Preservation of as much of the native stapes aspossible is conceptually appealing but may also have sub-stantial benefits for patients. The most common compli-cations occurring after stapedotomy involve the prosthe-

TABLE V.Preoperative Audiometric Data for Patients Undergoing Stapedioplasty.

PatientNo.

Age(y) Sex Ear

Pure Tones (Air) Pure Tones (Bone)

ABG (dB) SDS (%)500 1000 2000 3000 4000 8000 PTA* (air) dB 500 1000 2000 3000 4000 PTA* (bone) dB

1 43 M R 45 50 40 40 45 60 43.7 15 20 30 25 30 22.5 21.2 100

2 41 M L 65 60 45 NA 40 65 53.1 20 20 25 NA 20 23.1 30 96

3 55 M L 55 45 30 50 50 75 45 10 15 30 35 30 22.5 22.5 100

4 37 F L 70 60 60 50 65 65 60 20 15 25 20 20 20 40 100

5 39 F R 60 55 40 45 40 50 50 15 20 30 25 15 22.5 27.5 100

6 53 F L 70 65 60 65 75 90 57.5 30 35 55 45 40 41.3 16.2 92

7 42 M R 45 45 40 50 55 75 45 10 15 35 35 40 23.8 21.2 100

8 43 F L 50 45 35 25 30 45 38.8 15 25 20 10 15 17.5 21.3 100

9 34 F L 50 50 60 75 80 95 58.8 20 20 45 50 50 33.8 25 100

10 32 F L 60 50 40 35 40 40 46.3 25 15 20 15 15 18.8 27.5 100

11 48 F R 65 60 50 60 55 50 58.8 15 15 25 20 20 18.8 40 98

Av 50.6 Av 24.1 Av 26.6 Av 98.7

SD 7.04 SD 6.84 SD 7.30 SD 2.45

*PTA and air-bone gap based on four-tone average of 500, 1000, 2000, and 3000 Hz (or mean of 2k or 4k if NA).NA 5 not available; Av 5 average; ABG 5 air-bone gap; SDS 5 speech discrimination score; PTA 5 pure-tone average.

TABLE VI.Six-Week Postoperative Audiometric Data After Stapedioplasty.

PatientNo. Surgery Date


ABG* (dB)Improvementin ABG (dB) SDS (%)500 1000 2000 3000 4000 8000 PTA* (Air) dB 500 1000 2000 3000 4000 PTA* (Bone) dB

1 12/6/96 25 20 20 35 25 55 25 15 15 20 35 25 21.2 3.8 17.4 96

2 1/15/97 60 60 45 40 50 60 51.2 20 15 25 20 20 20 31.2 21.2 96

3 1/29/97 30 15 15 35 30 45 23.7 20 15 25 35 30 23.7 0 22.5 100

4 2/19/97 20 20 20 NA 15 30 19.4 20 20 15 NA 15 17.5 1.9 38.1 100

5 6/6/97 30 20 15 NA 30 40 21.9 15 15 15 NA 30 16.8 5.1 22.4 100

6 8/1/97 45 45 40 45 55 90 43.8 30 35 50 45 40 40 3.8 12.4 96

7 8/6/97 20 20 25 40 50 60 26.3 10 15 20 30 40 18.8 7.5 13.7 100

8 9/8/97 55 45 30 15 25 45 36.3 10 10 20 15 20 13.8 22.5 21.2 100

9 2/11/98 20 15 35 40 70 90 27.5 20 20 25 45 50 27.5 0 25 100

10 2/25/98 35 30 10 20 10 25 23.8 30 20 10 10 5 17.5 6.3 21.2 96

11 3/2/98 40 35 20 30 30 40 28.8 20 15 20 20 25 18.8 10 30 100

Av 29.8 Av 21.4 Av 8.3 Av 18.2 Av 98.5

SD 9.91 SD 7.16 SD 9.8 SD 11.9 SD 2.02

*PTA and air-bone gap based on four-tone average of 500, 1000, 2000, and 3000 Hz (or mean of 2 k and 4 k if NA).


21

sis.159 Eliminating the prosthesis which must protrudeinto the inner ear makes the procedure less invasive andmay reduce risks of granulation, infection, vertigo, andsensorineural hearing loss. Incus necrosis and slippedprosthesis problems would be eliminated. Preservation of

the stapedius tendon may improve word recognition inbackground noise and reduce hyperacusis,115 and preser-vation of the annular ring may improve protection fromloud noise exposure compared with procedures with aprosthesis. Longer-term studies with larger numbers of

TABLE VII.Six-Month or Greater Postoperative Audiometric Data After Stapedioplasty.

PatientNo. F/U (mo)



1 15 30 25 25 40 30 50 30 15 15 25 35 25 22.5 7.5 13.7 96

2 17 65 60 45 45 55 70 53.8 25 20 25 20 25 22.5 31.3 21.3 96

3 16 25 20 15 30 20 40 22.5 15 15 15 30 20 11.8 10.7 11.8 96

4 14 25 25 15 10 20 25 18.7 20 20 15 NA 15 17.5 1.2 38.8 100

5 12 40 25 20 NA 20 40 26.3 0 10 20 NA 15 11.9 14.4 13.1 92

6 10 35 30 40 NA 40 65 36.3 20 25 30 NA 30 26.3 10 11.2 100

7 9 15 15 20 25 30 35 18.8 10 15 20 25 30 17.5 1.3 19.9 100

8 8 30 25 15 15 10 30 21.3 5 10 15 15 10 11.3 10 11.3 100

Av 28.5 Av 17.7 Av 10.8 Av 14.8 Av 98.0

SD 11.87 SD 5.73 SD 9.4 SD 11.34 SD 2.98

*PTA and air-bone gap based on four-tone average of 500, 1000, 2000, and 3000 Hz (or mean of 2 k and 4 k if NA).F/U 5 follow-up.

TABLE VIII.Preoperative Audiometric Data for Patients Undergoing Stapedotomy.

PatientNo.

Age(y) Sex Ear


ABG (dB) SDS (%)500 1000 2000 3000 4000 8000 PTA* (Air) dB 500 1000 2000 3000 4000 PTA* (Bone) dB

1 45 M R 60 55 40 NA 25 40 46.9 25 15 20 NA 15 19.4 27.5 100

2 61 F R 70 55 70 60 70 75 63.8 30 20 45 35 45 32.5 31.3 92

3 45 M R 55 50 55 35 35 35 48.8 15 25 45 20 25 26.3 22.5 100

4 66 M L 50 55 75 75 80 70 63.8 15 15 60 60 55 37.5 26.3 100

5 30 M L 50 45 40 NA 45 35 44.4 20 10 35 NA 30 24.4 20 100

6 49 F R 55 55 55 50 50 50 53.8 15 15 35 30 30 23.8 30 100

7 52 M L 35 40 55 70 70 65 50 25 20 55 50 65 37.5 12.5 92

8 40 F R 60 60 50 50 45 60 55 15 15 30 20 15 20 35 96

9 43 F L 65 60 55 NA 45 35 57.5 10 20 15 NA 15 15 42.5 100

10 21 F L 35 30 30 NA 10 25 28.8 10 15 20 NA 10 15 13.8 100

11 50 M R 60 60 50 75 85 90 61.3 25 25 35 40 40 31.3 30 100

12 79 M R 80 75 60 80 65 100 73.8 15 15 20 45 40 23.8 50 88

13 48 M R 85 80 60 50 65 75 68.8 35 30 45 35 30 36.3 32.5 100

14 37 F R 55 55 65 70 75 80 61.3 30 20 45 50 50 36.3 25 100

15 34 F R 55 60 45 NA 40 45 50.6 25 25 35 NA 15 27.5 23.1 100

16 64 F L 95 80 55 50 75 95 70 40 35 35 40 45 37.5 32.5 96

17 39 F L 55 50 45 45 30 60 48.8 20 20 30 30 25 25 23.8 96

18 35 F L 55 55 40 45 45 45 48.8 10 25 20 20 15 18.8 30 100

19 40 F L 65 60 65 NA 105 .110 68.8 25 25 55 NA 65 41.3 27.5 92

20 41 F L 70 65 50 45 60 70 57.5 30 25 30 25 30 27.5 30 96

21 48 F L 60 40 25 NA 40 55 39.4 20 25 25 NA 25 23.8 15.6 100

22 46 M L 45 40 20 NA 25 20 31.9 10 10 20 NA 10 13.8 18.1 100

23 23 F R 55 50 40 40 30 40 46.3 10 5 15 10 10 10 36.3 100

Av 53.9 Av 26.3 Av 27. Av 97.7

SD 11.8 SD 8.82 SD 8.84 SD 3.58



22

patients and specific testing in background noise will berequired.160

Authors have previously noted difficulties with foot-plate surgery when the stapes superstructure is preservedand partially obscures the footplate. Early stapes mobili-zations failed frequently because of refixation of the frac-ture made through the anterior otosclerotic focus.2 Divi-sion of the footplate posterior to the margin of theotosclerotic focus and wide separation of the anterior crus(to prevent fusion of the crus), when possible, produced a

high rate of lasting success.29,35,161 Histopathologicalstudies examining stapes footplates mobilized years ear-lier have demonstrated healing with a fibrous union whenthe fracture did not involve the otosclerotic focus.51,52

These studies suggested that the enchondral bone of thestapes footplate may be resistant to bony healing, whichwould favor long-term results with a stapedioplasty. It isunknown whether laser burns through the stapes foot-plate will affect the healing process influencing a fibrousor bony repair. It is also unknown whether laser burns

TABLE IX.Six-Week Postoperative Audiometric Data After Stapedotomy.

PatientNo.

SurgeryDate



1 12/30/96 35 25 25 30 35 50 28.8 35 20 25 30 35 27.5 1.3 26.2 100

2 1/15/97 30 25 45 45 50 55 36.3 20 20 30 40 40 27.5 8.8 22.5 92

3 3/3/97 30 30 30 20 30 50 27.5 15 20 30 20 25 21.3 6.2 16.3 100

4 3/12/97 20 25 35 40 45 55 30 15 20 35 35 40 26.3 3.7 22.6 100

5 3/26/97 25 20 30 35 50 50 27.5 15 20 30 25 35 22.5 5 15 100

6 4/28/97 25 20 25 25 30 40 23.8 15 15 20 20 35 17.5 6.3 23.7 100

7 5/5/97 15 20 35 45 60 90 28.8 15 15 30 40 50 25 3.8 8.7 92

8 5/7/97 25 25 25 20 15 30 23.8 15 20 20 20 15 18.8 5 30 100

9 6/9/97 25 30 20 15 30 60 22.5 15 20 15 15 25 16.3 6.2 36.3 100

10 6/9/97 15 15 10 5 15 35 11.3 5 10 5 NA 10 6.9 4.4 9.4 100

11 7/21/97 20 15 20 35 40 55 22.5 20 15 20 35 40 22.5 0 30 100

12 7/28/97 45 25 30 60 75 95 40 30 20 20 NA 60 27.5 12.5 37.5 88

13 7/28/97 55 40 30 30 40 60 38.8 15 30 25 25 25 23.8 15 17.5 100

14 7/30/97 30 20 35 35 40 50 30 30 20 25 35 40 27.5 2.5 22.5 100

15 8/6/97 20 15 10 10 15 20 13.8 20 15 10 10 15 13.8 0 23.1 100

16 8/8/97 35 25 5 15 35 65 20 30 25 5 15 35 18.8 1.2 31.3 96

17 8/18/97 20 15 10 NA 20 55 15 20 10 10 NA 10 12.5 2.5 21.3 100

18 10/1/97 30 25 15 10 20 50 20 15 20 15 10 15 15 5 25 100

19 10/17/97 20 20 35 NA 70 90 31.9 20 15 35 NA 60 29.4 2.5 25 92

20 12/3/97 25 20 20 20 30 35 21.3 25 20 20 20 25 21.3 0 15.6 100

21 12/5/97 30 10 10 25 45 55 18.8 15 5 10 NA 30 12.5 6.3 9.3 100

22 2/20/98 15 10 15 NA 30 35 15.6 5 10 5 NA 15 7.5 8.1 10 100

23 2/20/98 25 20 15 15 15 30 18.8 10 10 15 15 10 12.5 6.3 30 100

Av 24.6 Av 4.90 Av 22.1 Av 98.3

SD 7.79 SD 3.77 SD 8.39 SD 3.58


TABLE X.Six-Month or Greater Postoperative Audiometric Data After Stapedotomy.

PatientNo. F/U (mo)


ABG (dB)Improvement in

ABG (dB) SDS (%)500 1000 2000 3000 4000 8000 PTA* (Air) dB 500 1000 2000 3000 4000 PTA* (Bone) dB

1 9 30 25 20 NA 25 55 24.4 25 15 20 NA 25 20.6 3.8 23.7 100

3 11 30 35 40 30 45 35 33.8 30 35 35 25 35 31.3 2.5 28.8 92

4 14 25 20 35 40 40 60 30 15 20 35 40 40 27.5 2.5 1.2 100

5 6 25 20 15 NA 35 25 21.3 10 10 15 NA 25 13.8 7.5 12.5 100

Av 27.4 Av 23.3 Av 4.1 Av 16.6 Av 98.0

SD 5.60 SD 7.73 SD 2.36 SD 12.2 SD 4.00



23

through an otosclerotic focus could impede regrowth andexpand the indications for stapedioplasty beyond cases oflimited anterior otosclerosis.

Early anterior crurotomy and stapedioplasty tech-niques were difficult and results somewhat unpredictablewithout the precise tools of modern microdrills and lasers.Fiberoptic delivered lasers make it possible to direct energyonto areas of the stapes and footplate that may not be visiblewith the operating microscope. It has been suggested thatfiber delivered lasers could be used to revive these stapespreservation techniques, and Silverstein1 has shown favor-able early clinical results. Silverstein noted difficulties inperforming the technique attributable to problems visualiz-ing the anterior crus and entire footplate. He removed morescutum than is customary, to improve visualization and al-low for a bent argon laser fiber to contact the anterior crus.Two patients had inadvertent fractures of the posterior crus,presumably attributable to the difficulties of manipulatingthe bent laser probe around difficult-to-visualize areas.Some of the stapes could not be mobilized and surgery wasconverted to a prosthesis technique.

Improvements in stapedioplasty technique could begained by better visualization devices, more optimal laserwavelengths, and angled laser delivery systems.

Endoscopes were examined to enhance the visualiza-tion of the footplate and anterior crus with an intactstapes superstructure. Previous fiberoptic images hadpoor resolution, and Hopkins rod rigid lenses are consid-erably larger and awkward in middle ear surgery. Thefiberoptic argon and diode laser endoscopes with 10k im-aging pixels that were used in this study demonstratedimproved optics over previous fiber instruments, but theresolution was still lacking compared with an operatingmicroscope and was thought to be insufficient. The advan-tages of the laser probe fitted with the 3-mm protrudinglaser tip were that the entire instrument could be held inone hand and the tip was visible in the endoscopic field. It

was very convenient to use but sometimes required alter-nating between using the laser, then returning to themicroscope, to really appreciate what the laser had accom-plished (Figs. 15 and 16). The protruding tip allowed theendoscope to be easily used for palpation, and there wereno problems with splatter onto the endoscope lens. Thefiber tip protruded straight forward and a frequent prob-lem was encountered—that a laser target could be easilyseen within the 85-degree endoscope view angle but thelaser tip could not be angled and brought onto the target.An angled laser tip will be necessary for expanded uses inthe future, since the principal use of an endoscope is tovisualize around the corners that cannot be negotiatedwith a microscope.

The GRIN endoscopes appeared to be a significantadvance in design of small endoscopes. The images werenot as bright and resolution was not as sharp as a Hopkins

Fig. 15. Intraoperative view of left stapeswith gradient-index lens laser endoscope.Contact laser tip is evident at periphery ofimage at 11 o’clock position.

Fig. 16. Intraoperative view of same ear as in Fig. 15, visualized withoperating microscope for comparison.


24

rod lens, but at less than half the diameter, the improvedfacility of use was promising. The GRIN scope that wasused was 0.5 mm in diameter but was bundled into a laserpackage for a total OD of 1.2 mm. The image quality wassufficient to perform surgical procedures without contin-uously returning to the operating microscope. The sizewas small enough that it could be maneuvered close to theossicles and the 0-degree view angle made it easier tooperate with a separately handheld laser than if it hadbeen an angulated view. Hopkins scopes so large that theycannot be maneuvered close to the ossicular chain andgenerally require a 30-degree view angle for middle earsurgery. GRIN endoscopes may be useful in future designsof small endoscopes and endoscopic laser devices.

The limitations of CO2, argon, and KTP lasers forotological surgery are well known. Argon and KTP lasers,which are most commonly used for stapes surgery, areactually poorly absorbed by bone and work only becausethere is usually sufficient hemoglobin exposed in the verythin bone of the stapes. Slightly thicker bone in the foot-plate or posterior crus produces difficulties in penetrationwith these visible lasers. It seems clear that technologicalimprovements are still required to improve the techniquesfor stapes surgery without a prosthesis.

It has been anticipated that newer mid-IR lasers willbecome available that will be absorbed well by water, aswith CO2 lasers, and still be fiberoptic delivered, as areargon and KTP lasers. The only mid-IR lasers commer-cially available to date have been pulsed varieties such aserbium, holmium, and pulsed thulium lasers.

Pulsed mid-IR lasers operate around the peak ab-sorption wavelength for water (3.0 mm) and were hoped tobecome the next advance in otological lasers. Their highwater absorption would be useful in all tissue types, re-gardless of pigmentation, and overlying perilymph wouldbe protective of the membranous labyrinth during stapesfootplate fenestration. The pulsed quality would be favor-able for creating sharp vaporization craters with minimaladjacent thermal injury. However, the pulsed quality pro-duces sufficient acoustic shock that the potential for hear-ing injury from noise trauma and propagation of the pho-tomechanical impact with concussive and shearing forceson the labyrinthine hair cells are very significant con-cerns. Hearing injury has been documented in guineapigs150 and to a limited degree in the first clinical experi-ence using the erbium laser.155 It is possible that prolong-ing the pulse width in future designs would reduce theacoustic shock sufficiently to minimize the potential forhearing injury while still preserving the laser’s favorablebone vaporization characteristics.

Continuous-wave lasers with IR outputs and im-proved water absorption characteristics remain in the pro-totype category at present. The thulium CW laser ap-peared to have many of the desired properties andfunctioned nicely in cadaver tissues. Further studies withthese prototype devices will be needed.

A promising new category of IR lasers is the diodetype, since they are efficient, fiber delivered, and rela-tively inexpensive. Current commercially available diodelasers with clinically useful outputs from 1 to 10 W oper-ate only in near-IR range, which falls into the trough

between hemoglobin and water absorption. They were notuseful for free beam photothermal outputs in most tissuesevaluated in this study unless the tissue were darklypigmented or stained with dark blood or the tissue absorp-tion was enhanced with ICG dye.

Evaluation of near-IR lasers and the associated de-livery systems was performed in the anticipation thatmid-IR diode lasers already exist in the milliwatt outputrange and it is probably just a matter of time before thesewavelengths are available in clinically useful outputs upto 10 W. Laser endoscopic stapes surgery with the diodelaser using ICG to improve absorption proved useful. Wehave made CAP measurements of auditory thresholds inguinea pigs and did not find any significant acute hearingchanges with CW diode laser exposure. The auditory mea-surements will be presented in a separate report.

Contact laser probes available with the diode laserprovided a potentially new surgical tool for otological sur-geons. Contact tips have been widely used with the Nd:YAG laser but threw off so much heat that it would havebeen inconceivable to use them in an ear. Contact fibersheat more slowly than photothermal methods and mayoccur over a relatively broad tip, producing wide margins ofadjacent thermal injury, particularly in bone. The 100-mmfiber used in this study focused the heat so well that focalburns closely resembled those of conventional otological la-sers. The thermal measurements in the vestibules averaged3.3°C of elevation and did not exceed 4.3°C of elevation withthe 100-mm fibers when making 10 burns on the footplate.Elevations up to 3.5°C have been previously described as“modest.”162 The temperature elevation could easily be re-duced by spacing each burn by 5 to 10 seconds.

The contact probe behaved much like a fiberoptic(free beam) probe with poor effect on nonpigmented tissueuntil it was thoroughly burned-in, applying it to soft tissueor blood for multiple burns and creating some char on thetip. Caution must be exercised to be certain that the tip isreproducibly heating tissue before applying it to the sta-pes. If the probe were used without the burning-in proce-dure, heating of as much as 26°C occurred in the vestibulethermal measurements without any significant superficialburn to warn the surgeon of ongoing underlying injury.The diode laser energy is poorly absorbed by the whitefootplate and has a penetration distance of about a centi-meter in water as a free beam. Fiber manufacturers maybe able to improve the contact performance of future tipsto reduce the potential for free beam (photothermal oroptical) energy transmission without requiring a burn-inprocedure.

The 100-mm contact fiber should be further investi-gated for potential use in otological surgery. Once the tipis ensured to be functioning in contact mode, it will vapor-ize or cauterize tissue, regardless of pigmentation, includ-ing blood vessels, granulations, cholesteatoma, and bone.The tip does not rely on optical qualities and may be freelyused for cold dissection, unlike a free beam fiber tip, whichwill lose performance when the tip is contaminated withtissue fluid or debris. Contact fibers could be incorporatedinto endoscopic devices for precision dissection under di-rect visualization around corners and within recesses notseen with the operating microscope.


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In the future, otological endoscopes will be designedin two basic types, rigid lenses for high resolution andsmaller, steerable fiberoptics. Small (,1 mm) rigid lenssystems that may combine elements of Hopkins rod andGRIN lenses will be fitted with contact or free beam laserfibers for precise surgical procedures requiring high-resolution optics comparable to an operating microscope.These instruments will generally be 0-degree forwardviewing. Steerable fiberoptics will be available in smaller-diameter packages with increasingly better resolution astechnology is able to increase the number of pixels insmall fiber bundles. These devices will be used in tighterrecesses and for traveling deeper into the temporal bone toaccess disease. The smaller size and flexibility of the in-struments will offset the reduction in resolution. They willbe particularly helpful in the eustachian tube, petrousapex, and cerebellopontine angle.

Manufacturers will be tasked to produce fiber tipdesigns that will protrude from the endoscope imagingbundle 3 to 5 mm, as in the prototype evaluated in thisstudy. A laser tip flush with the endoscope tip must bebrought into near or actual contact with the tissues forcold dissection and laser treatment. A protruding tip re-moves the potential for thermal injury or splatter to theimaging fibers and permits free beam tips to be broughtinto near contact for optimal performance while remain-ing in clear endoscopic focus. Angulation of the tips will benecessary to take advantage of the wide fields of endo-scopic view, particularly in the rigid endoscopes.

Mid-IR diode lasers will probably be available in thenot too distant future. As with other diode lasers, high-efficiency performance will make them small, portable,and relatively inexpensive. The availability of lasers inotological surgery may increase beyond just the majormedical centers and possibly into the practitioners’ offices.It is anticipated that endoscopic coupling with these laserswill increase the ability to do minimally invasive otologi-cal surgery such as debridement and definitive cauteriza-tion of limited cholesteatomas, myringotomies, vaporiza-tion of retraction pockets, spot-welded tympanoplasties,eustachian tube surgery, and other middle ear and mas-toid treatments in an outpatient or office setting. Endo-scopic laser-welded tympanoplasties are already beingroutinely performed by the author and will be presented inthe future. There is potential for image-guided interstitialplacement of these devices into cavities within the skullbase and cerebellopontine angle for treatment of lesionssuch as cholesterol cysts, epidermoid tumors, glomus andtumors. For the present, the currently available diodelasers with the 100-mm contact tip should be further stud-ied for possible clinical potential.

The early clinical experience with stapedioplasty re-ported by Silverstein1 and in the present study suggeststhat the techniques are feasible with short-term resultscomparable to conventional stapedotomy. The stapedio-plasty patients in the present study demonstrated im-proved hearing results at the 6-week and 6-monthfollow-up periods comparable to the stapedotomy controlgroup. The postoperative air-bone gap at 6 weeks was 8.3dB (SD 9.8) for stapedioplasty and 4.9 dB (SD 3.77) forstapedotomy. The gap and SD were slightly higher for the

stapedioplasty group because of patient 2, who was notsuccessful in closing the gap, and patient 8, who had anupper respiratory tract infection and effusion at the post-operative visit and subsequently improved the gap to 10dB. Six-month follow-up was obtained in 8 of the 11 sta-pedioplasty patients and showed that there was littleoverall change with the air-bone gap at 10.8 dB (SD 9.4).Patient 5 showed a significant drop in air-bone gap from5.1 dB at 6 weeks to 14.4 dB at 6 months, but the 6-monthbone line was considerably improved while the air linechanged little from pure-tone average (PTA) 21.9 dB toPTA 26.3 dB. There were no other significant changes inthe air-bone gaps at 6 months, and it would appear thatbone refixation with return of a preoperative air-bone gaphas not occurred in any patient. It may be concluded thatin this preliminary study of stapedioplasty, it is possible toobtain short-term results comparable to conventional sta-pedotomy without an increase in complication rates. The6-month follow-up results have not shown refixation of thefootplate in any case to date, and further study of thetechnique is warranted to determine long-term outcomesin larger cohorts. Six of the stapedioplasty patients havebeen followed up for more than 1 year and have all main-tained their air-bone gap closure, demonstrating that con-tinued mobility of the stapes over time is possible.

The second patient to undergo the procedure did nothave a satisfactory closure of the air-bone gap, which waslikely, in retrospect, to be a failure to adequately judge thestapes mobility. It was noted that some flexibility of theposterior crus on palpation may be misinterpreted as foot-plate mobility. True footplate mobility must be judged bydirect visualization of vertical displacement of the poste-rior footplate relative to the stationary anterior segmentduring palpation of the posterior crus or footplate itself.There was a large enough gap in the footplate after divi-sion that observation for a round window cochlear reflex tostapes movement was unsuccessful.

The indication for stapedioplasty in otosclerosis islimited to the anterior third of the footplate. It should beotherwise thin and apparently free of otosclerotic fixationaround the annular ligament beyond the margin of theanterior third. Most of the anterior and middle footplateshould be visible, despite the intact stapes superstructure.If the footplate is not easily mobilized with footplate divi-sion, the procedure may be converted to a standard sta-pedotomy with piston by separation of the ISJ, lysis of thestapedius tendon, and laser fenestration of the footplate.Thirteen patients (38.2%) appeared to be candidates forstapedioplasty in this study and had an attempt made.Two of the 13 (15.4%) patients were converted to conven-tional stapedotomy because of inability to adequately mo-bilize the footplate. Improvements in technique with ap-propriate instrumentation would be expected to increasethe number of successful stapedioplasties. Longer-termstudies will be required to determine a rate of refixation,which will ultimately determine whether stapedioplastywould be a worthwhile procedure.

There was no statistical significance between the pre-operative hearing levels and the intraoperative pattern orextent of otosclerosis. Larger numbers of patients in thefuture may reveal trends that could help predict the po-


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tential for stapedioplasty preoperatively. For now, pa-tients must be counseled that stapedioplasty may be at-tempted based on limited otosclerotic involvement,favorable anatomy, and ability to mobilize the footplateonce the procedure is attempted.

Causse (personal communication, February 1998)has cautioned that blind laser applications to the superiorrim of the footplate could risk injury to the sacculus, whichbecomes more superficial superiorly. It is recommendedthat the laser be applied only where directly visualizedand that an oval window pick or rasp could be used topalpate and divide remaining areas of footplate fixationout of sight.

Endoscopes improve the footplate visualization, butcurrently most are not well suited for this purpose. Fiber-optic endoscopes used in this study had insufficient reso-lution, and Hopkins rods were too large in diameter to bepractical and work the laser fiber around them. Somefootplate and anterior crus burns were performed usingthe rod endoscope and a separately handheld argon laserfiber, but the technique was quite difficult. Lysis of theanterior crus with the laser fiber endoscope prototype wasfar easier to perform with a single instrument, but thelack of an angled laser tip prevented any useful footplatesurgery unless a separately handheld laser fiber wereintroduced. A GRIN endoscope with superior optics com-bined with angled laser tips should significantly facilitatethe anterior crus and footplate surgery in the future.

CONCLUSIONStapedotomy without a prosthesis (stapedioplasty) is

a less invasive procedure than prosthesis insertion andmay be shown in the future to reduce the complicationsassociated with footplate fenestration including sensori-neural hearing loss, vertigo, infection, and granuloma for-mation. Prosthesis problems and incus necrosis should beeliminated. Improved hearing in background noise mayoccur with preservation of the stapedius tendon, and hy-peracusis may be reduced. Performance of the stapedio-plasty may be a technically more challenging procedurethan conventional stapedotomy because the intact super-structure impedes the view of the entire footplate anddivision of the anterior crus must often be accomplishedwithout direct visualization. Currently available endo-scopes may improve visualization but remain impracticaland await modifications designed for the limited spaces ofthe middle ear. Present fiber delivered lasers are usuallysatisfactory but have limited vaporization capability onbone and may present risks to the sacculus when operatednear the superior rim of the oval window where the sac-culus is most superficial, since the wavelengths are notabsorbed by perilymph.

This study found that endoscopes did improve theviews of the anterior crus and stapes footplate, but eachsystem that was evaluated had drawbacks. The fiberopticlaser endoscope was most favorable, providing an ade-quate field of view and a protruding argon laser tip thatworked well on the anterior crus and limited areas of thefootplate. An angled tip would be needed to reach into therecess below the superstructure to complete the operationwith the laser endoscope alone. The resolution of the fiber

endoscope was insufficient for its exclusive use and re-quired frequent use of the operating microscope. Improvedfiberoptics with increased pixels may result in future fiberdevices of adequate resolution. The GRIN endoscope pro-vided excellent resolution in a small diameter suitable forstapes surgery but lacked an argon laser fiber for clinicaluse. Separate handheld laser fibers may be used, andintrinsic laser capability with other wavelengths is recom-mended with a protruding straight and angulated tip.

Various laser types were assessed in searching forthe following characteristics that would most closely ap-proximate the ideal otological laser:

1. High water absorption.2. Fiber delivery system.3. No acoustic shock.4. Clean vaporization of tissue with minimal adjacent

thermal injury.Pulsed lasers currently are not recommended, since

they have been shown to have acoustic shock propertiesthat may cause significant injury to the labyrinth.

The CW thulium laser showed initial promise as afiber delivered, mid-IR laser (2.1 mm), with favorable softtissue and bone effects. In its present form it is a large,water-cooled, expensive device that is unlikely to be clin-ically available in the immediate future and requires fur-ther study.

The diode lasers in the mid-IR range are fiber deliv-ered but lack the power for clinical use. They are expectedto become important in the future as efficient and inex-pensive devices that may expand laser capability to manymore medical centers and offices. Current diode lasersoperating in the near-IR range may be useful in otologywith contact probe fibers. This study demonstrated thatthe bone and soft tissue effects with a 100-mm conicaltapered tip were very favorable and elevated vestibuletemperatures a mean of 3.25°C and no more than 4.3°Cduring stapes footplate applications. Further study of thecontact probes should be performed to determine the clin-ical potential of these devices, which are currently avail-able. If results are satisfactory, they could be incorporatedinto endoscopic devices and advance the ability to performminimally invasive procedures in otology.

Stapedioplasty has been demonstrated to have thecapability of acutely closing the air-bone gap as well aswith a conventional procedure with a prosthesis. One-yearresults that fibrous healing and not bony refixation mayoccur in the majority of cases are encouraging, but long-term follow-up will be essential to determine the truefailure rate. Endoscopic visualization and improved laserwavelengths and delivery systems promise to simplify thetechnical demands of current stapedioplasty and possiblyincrease the indications.

ACKNOWLEDGMENTCredit is gratefully given to Mark Sabo for medical

illustrations and Kathy Hicks for manuscript preparation.

BIBLIOGRAPHY1. Silverstein H. Laser stapedotomy minus prosthesis (laser

STAMP): a minimally invasive procedure. Am J Otol 1998;19:277–282.


27

2. Rosen S. Rosen mobilization and stapedectomy: long-termresults with special reference to high frequencies. ArchOtolaryngol 1969;89:241–244.

3. Fowler EP Jr. Anterior crurotomy and mobilization of theankylosed stapes footplate. Acta Otolaryngol 1957;46:318.

4. Valsalva AM. Tractus de Avre Humana. Bologna, 1704.5. Blake C. Middle ear operations. Trans Am Otol Soc 1882;

512:306.6. Wilde WR. Practical Observations on Aural Surgery and of

the Nature and Treatment of Diseases of the Ear. Philadel-phia: Blanchard and Lea Publishers, 1853.

7. Kessel J. Ueber die Durchschneidung des Steigbugel-muskels beim Menschen. Arch Ohrenheilkd 8:321,1874;11, 1876; 12:237, 1877. As abstracted from Bellucci R.Repair and consequences of surgical trauma to the ossiclesand oval window of experimental animals. Trans Am OtolSoc 1958.

8. House HP. The evolution of otosclerosis surgery. Otolaryn-gol Clin North Am 1993;26:323–333.

9. Kessel J. Uber das Mobilisieren des Steogbugels durch Aus-schneiden des Trommelfelles, Hammers und Amboss beiundurchganikeit der Tuba. Arch Ohrenheilkd 1878;13:69–88.

10. Baracz R. Die Exzision des Trommelfells sammt Hammerbei sklerose der Paukenschleimhaut. Wien Med Wochen-schr 1887;37:290.

11. Lucae A. Ueber operative Entfernung des Trommelfells undder beiden grosseren Gehorknochelchen bei Sklerose dePaukenschleimhaug. Arch Ohrenheilkd 1885;22:233.

12. Boucheron E. La mobilisetion de l’etrier. Rev Laryngol 1890;10:49, 83, 145, 200.

13. Moure EJ. De la mobilisation de l’etrier. Rev Laryngol 1880;7:225–233.

14. Miot C. De la mobilisetion de l’etrier. Rev Laryngol 1890;10:49, 83, 145, 200.

15. Blake C. Stapedectomy and other middle ear operations.Trans Am Otol Soc 1891–93;5:464.

16. Jack F. Remarks on stapedectomy. Trans Am Otol Soc 1893;6:102.

17. Grunert K. Was Konnen wir von der operativen Entfernungde Steigbugels bei Steigbugel-Vorhofankylose zum zwekder Horrerbesserung erhoffen? Arch Ohrenheilkd 1896;41:294.

18. Siebenmann F. Traitement chirurgical de la sclerose otique.Congr Int Med Sec Otol 1900;13:170.

19. Hillel AD. History of stapedectomy. Am J Otolaryngol 1983;4:131–140.

20. Passow H. In: Panse R. Discussion. Verh Dtsch Otol Ges1897;6:141.

21. Floderus B. Bidrag till stigbygelankylosens operativaradikalbehandlung. Nord Med Arch 1899;32:1.

22. Jenkins GJ. Otosclerosis: certain clinical features and ex-perimental operative procedures. Trans XVII Int CongrMed 1913;16:609.

23. Holmgren G. Some experiences in the surgery of otosclero-sis. Acta Otolaryngol 1923;5:460.

24. Holmgren G. The surgery of otosclerosis. Ann Otol RhinolLaryngol 1937;46:3–12.

25. Sourdille M. New technique in the surgical treatment ofsevere and progressive deafness from otosclerosis. Bull N YAcad Med 1937;13:673.

26. Lempert J. Improvement in hearing in cases of otosclerosis:a new, one stage surgical technic. AMA Arch Otolaryngol1938;28:42.

27. Lempert J. Principles used in the development of moderntemporal bone surgery. AMA Arch Otolaryngol 1959;69:515.

28. Lempert J. Tympanosympathectomy. Arch Otolaryngol1946;43:199.

29. Goodhill V. Stapes Surgery for Otosclerosis. New York: PaulB. Hoeber, Inc. Medical Division of Harper & Brothers,1961.

30. Rosen S. Mobilization of the stapes to restore hearing inotosclerosis. N Y J Medicine 1953;53:2650.

31. Rosen S. Mobilization of stapes for otosclerotic deafness.AMA Arch Otolaryngol 1957;65:129.

32. Rosen S. The development of stapes surgery after five years.AMA Arch Otolaryngol 1958;67:129.

33. Herrman H. Mobilisierung des steigbugels durch ausmeis-seln und einwartsverlagern der fussplatte. Ztchr LaryngolRhinol Otol 1956;35:415.

34. Herrman H. Experiences with 200 stapes mobilizations.HNO Berlin 1959;7:172.

35. Goodhill V, Shea J, Derlacki E, et al. Otosclerosis sympo-sium. Arch Otolaryngol 1960;71:246.

36. Holmgren L. Stapediolysis in otosclerosis. Acta Otolaryngol1957;48:219.

37. Bellucci R, Wolff D. Regression of hearing improvementafter mobilization of the stapes. Laryngoscope 1959;69:241.

38. Juers AL. Stapedioplasty: a new concept for stapes surgery.Laryngoscope 1959;69:1180.

39. Juers AL. Stapedioplasty. AMA Arch Otolaryngol 1960;71:305.

40. Goodhill V. Stapedolysis and the nomograph technic. JSpeech Hear Disord 1958;1:179.

41. Hough JVD. Partial stapedectomy. Ann Otol Rhinol Laryn-gol 1960;69:571.

42. Bellucci RJ. Guide for stapes surgery based on new surgicalclassification of otosclerosis. Laryngoscope 1958;68:759.

43. Tweedle AR. Otosclerosis: etiology, development and treat-ment. Arch Otolaryngol 1908.

44. Drury DW. Otosclerosis. Ann Otol Rhinol Laryngol 1926;35:651.

45. Hagens EW. Otosclerosis. Arch Otolaryngol 1930;12:273.46. Goodhill V, Harris I. Surgical treatment of otosclerosis. In:

English, ed. Otolaryngology. JB Lippincott, 1991;1:48.47. Hough JVD, Dyer RK. Stapedectomy: causes of failure and

revision surgery in otosclerosis. Otolaryngol Clin NorthAm 1993;26:453–470.

48. Hough JVD. Otosclerosis: The method of J.V.D. Hough,M.D. In: Gates GA. Current Therapy in Otolaryngology-Head and Neck Surgery. New York: BC Decker, 1982:24.

49. Hough JVD. Long-term results in partial stapedectomy.Arch Otolaryngol 1989;89:230.

50. Portmann M. Procedure of “interposition” for otoscleroticdeafness. Laryngoscope 1960;70:166.

51. Meyers E, Ishiyama E, Heisse J Jr. Histology of a successfulstapes mobilization. Ann Otol Rhinol Laryngol 1970;79:321–325.

52. Lindsay JR, Hilding AC, McLaurin JW, et al. Histopatho-logic changes following fenestration and stapes mobiliza-tion. Trans Am Acad Ophthalmol Otolaryngol 1959;63:187–205.

53. Shea J Jr. Fenestration of the oval window. Ann Otol RhinolLaryngol 1958;67:932–951.

54. Schuknecht HF, Oleksiuk S. The metal prosthesis for stapesankylosis. Arch Otolaryngol 1960;71:287–295.

55. Schuknecht HF. The metal prosthesis for stapes ankylosis.AMA Arch Otolaryngol 1960;71:287.

56. Robinson M. A four-year study of the stainless steel stapes.Arch Otolaryngol 1965;82:217–235.

57. Fernandez C, Allen G, Lindsay J. Experimental studies infixation of the stapes and fenestra ovalis. Laryngoscope1958;68:1881.

58. Moon CN Jr, Hahn MJ. Partial vs. total footplate removal instapedectomy: a comparative study. Laryngoscope 1984;94:912–915.

59. Robinson M. Total footplate extraction in stapedectomy.Ann Otol 1981;90:630–636.

60. Fisch U. Stapedotomy versus stapedectomy. Am J Otol1982;4:112–117.

61. Persson P, Harder H, Magnuson B. Hearing results in oto-sclerosis surgery after partial stapedectomy, total stape-dectomy and stapedotomy. Acta Otolaryngol 1997;117:94–99.

62. Shea JJ. Thirty years of stapes surgery. J Laryngol Otol1988;102:14–19.


28

63. Fisch U. Stapedectomie oder stapedotomie? HNO 1979;27:361.

64. House H. Early and late complications of stapes surgery.Arch Otolaryngol 1963;78:606.

65. Marquet J, Creten WL, VanCamp KJ. Considerations aboutthe surgical approach in stapedectomy. Acta Otolaryngol1972;74:406.

66. Paparella MM. The effect of trauma in causing cochlearlosses after stapedectomy. Acta Otolaryngol 1966;62:33.

67. Stahle J, Hogberg L. Laser and labyrinth. Acta Otolaryngol1965;60:367–374.

68. Stahle J, Hoberg L. Laser and the labyrinth: some prelimi-nary experiments on pigeons. Acta Otolaryngol 1965;60:367–374.

69. Kelemen G, Klein E, Laor Y. Laser irradiation and hearingorgan. Proc Pan Am Congr Otolaryngol 1966:4.

70. Kelemen G, Laor Y, Klein E. Laser-induced ear damage.Arch Otolaryngol 1967;86:21–22.

71. Sataloff J. Experimental use of laser in otosclerotic stapes.Arch Otolaryngol 1967;85:58–60.

72. Stahle J, Hogberg L, Engstrom B. The laser as a tool in innerear surgery. Acta Otolaryngol 1972;73:27–37.

73. Wilpizeski C, Sataloff J, Doyle C, et al. Selective vestibularablation in monkeys by laser irradiation. Laryngoscope1972;82:1045–1058.

74. Wilpizeski C, Sataloff J. Long-term consequences of vestib-ular ablation by laser in a monkey. Laryngoscope 1974;84:273–280.

75. Sugar J, Stahle J, Hogberg L. Laser irradiation of the striavascularis. Arch Otolaryngol 1974;99:330–336.

76. Wilpizeski C, Maioriello RP, Reddy JB, et al. Otologic appli-cations of lasers: basic background and early animal find-ings. Trans Penn Acad Ophthalmol Otolaryngol 1977;30:185–191.

77. Wilpizeski C. Experimental CO2. laser surgery of the ear: acaveat based on primate subject and cadaver temporalbones. In: Kaplan I, ed. Laser Surgery: Dallas—Proceed-ings of the Second International Symposium on Laser Sur-gery. 1977:19–103.

78. Lyons GD, Webster DB, Mouney DR, et al. Anatomical con-sequences of CO2 laser surgery of the guinea pig ear. La-ryngoscope 1978;88:1749–1754.

79. Escudero LH, Castro AO, Drummond M, et al. Argon laserin human tympanoplasty. Arch Otolaryngol 1979;105:252–253.

80. Palva T. Argon laser in otosclerosis surgery. Acta Otolaryn-gol 1979;104:153–157.

81. Epley JM. Tympanic membrane debridement with the CO2laser. Otolaryngol Head Neck Surg 1981;89:898–902.

82. DiBartolomeo JR, Ellis M. The argon laser in otology. La-ryngoscope 1980;90:1786–1796.

83. Lima JA, Wilpizeski CP. Effectiveness of the CO2 laser inexperimental neurectomy. Laryngoscope 1980;90:414–422.

84. DiBartolomeo JR. The argon and CO2 lasers in otolaryngol-ogy: which one and why? Laryngoscope 1981;91:1–16.

85. Wilpizeski CR. Letter to the editor. Laryngoscope 1981;91:834–835.

86. Epley JM. Tympanic membrane debridement with the CO2laser. Otolaryngol Head Neck Surg 1981;89:898–902.

87. Williams DF, Hunter-Duvar IM, Mitchell DP. The use of theCO2 laser in otology. Ann Otol Rhinol Laryngol 1981;90:70–71.

88. Glasscock ME, Jackson CG, Whitaker SR. The argon laserin acoustic tumor surgery. Laryngoscope 1981;91:1405–1416.

89. Vollrath M, Schreiner C. The effects of the argon laser ontemperature within the cochlea. Acta Otolaryngol 1982;93:341–348.

90. Schreiner C, Vollrath M. Effect of argon laser stapedotomyon cochlear potentials. Acta Otolaryngol 1983;95:47–53.

91. Schreiner C, Vollrath M. Effect of argon laser stapedotomyon cochlear potentials, II: alteration of compound actionpotential (CAP). Acta Otolaryngol 1983;95:45–53.

92. Schreiner C, Vollrath M. Influence of argon laser stape-dotomy on cochlear potentials, III: extracochlear recordedDC potential. Acta Otolaryngol 1983;96:49–55.

93. Vollrath M, Schreiner C. Influence of argon laser stape-dotomy on inner ear function and temperature. Otolaryn-gol Head Neck Surg 1983;91:521–526.

94. Thoma J, Unger V, Kastenbauer E. Temperatur- und druck-messungen im innenohr bei der Anwendung des argon-laser. Laryngol Rhinol Otol 1981;60:587–590.

95. Gantz BJ, Kishimoto S, Jenkins HA, et al. Argon laserstapedotomy. Ann Otol Rhinol Laryngol 1982;91:25–26.

96. Goode RL. CO2 laser myringotomy. Laryngoscope 1982;92:420–423.

97. Gardner G, Robertson J, Bellott A, et al. 105 Patients oper-ated upon for cerebellopontine angle tumors: experienceusing combined approach and CO2 laser. Laryngoscope1983;93:1049–1055.

98. Gardner G, Robertson JH, Tomoda K, Clark WC. CO2 laserstapedotomy: is it practical? Am J Otolaryngol 1984;5:108–117.

99. Coker NJ, Ator GA, Jenkins HA, et al. Carbon dioxide laserstapedotomy: a histopathologic study. Am J Otolaryngol1986;7:253–257.

100. Thoma J, Mrowinski D, Kastenbauer ER. Experimentalinvestigations on the suitability of the carbon dioxide laserfor stapedotomy. Ann Otol Rhinol Laryngol 1986;95:126–131.

101. McGee TM. The argon laser in surgery for chronic ear dis-ease and otosclerosis. Laryngoscope 1983;93:1177–1182.

102. McGee TM. Lasers in otology. Otolaryngol Clin North Am1989;22:233–238.

103. Ricci T, Mazzoni M. Experimental investigation of temper-ature gradients in the inner ear following argon laser ex-posure. J Laryngol Otol 1985;99:359–362.

104. Vernick DM. A comparison of the results of KTP and CO2laser stapedotomy. Am J Otol 1996;17:221–224.

105. Lesinski SG, Palmer A. Lasers for otosclerosis: CO2 vs. argonand KTP-532. Laryngoscope 1989;99:1.

106. Lesinski SG. Reply to McGee JM and Kartush JM: letter tothe editor. Laryngoscope 1990;100:106–107.

107. McGee JM, Kartush JM. Letter to the editor. Laryngoscope1990;100:106–107.

108. Vernick DM. Letter to the editor. Laryngoscope 1990;100:108–109.

109. Lesinski SG, Palmer A. CO2 laser for otosclerosis: safe en-ergy parameters. Laryngoscope 1989;99:9.

110. Hohmann A. Inner Ear Reactions to Stapes Surgery (AnimalExperiments) in Otosclerosis. Boston: Little Brown & Co.,1962:305–317.

111. Linthicum F. Histologic evidence of the cause of failure instapes surgery. Ann Otol Rhinol Laryngol 1971;80:67–77.

112. Lesinski SG, Stein JA. Stapedectomy revision with the CO2laser. Laryngoscope 1989;99:13.

113. Lesinski SG, Stein JA. CO2 laser stapedotomy. Laryngoscope1989;99:20.

114. Gherini S, Horn KL, Causse JB, McArthur GR. Fiberopticargon laser stapedotomy: is it safe? Am J Otol 1993;14:283–289.

115. Causse JB, Gherini S, Horn KL. Surgical treatment of stapesfixation by fiberoptic argon laser stapedotomy with recon-struction of the annular ligament. Otolaryngol Clin NorthAm 1993;26:395–416.

116. Gherini S, Horn K, Kauffman K. “Endo-otoprobe” aids sta-pedotomy, other otologic laser procedures. In: Laser Prac-tice Report. Atlanta: Clinical Laser Monthly, 1988.

117. Silverstein H, Rosenberg S, Jones R. Small fenestra stape-dotomies with and without KTP laser: a comparison. La-ryngoscope 1989;99:485–488.

118. McGee TM. The argon laser in surgery for chronic ear dis-ease and otosclerosis. Laryngoscope 1983;93:1177–1182.

119. Horn KL, Gherini SG, Griffin GM. Argon laser stapedotomyusing an endo-otoprobe system. Otolaryngol Head NeckSurg 1990;102:193–198.

120. Gherini SG, Horn KL, Bowman CA, et al. Small fenestra


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stapedotomy using a fiberoptic hand-held argon laser inobliterative otosclerosis. Laryngoscope 1990;100:1276–1282.

121. McGee Tm. The KTP-532 laser in otology: KTP-532 clinicalupdate. Laserscope 1988.

122. Horn KL, Gherini SG. Otologic argon laser surgery using anendo-otoprobe system. Am Acad Otolaryngol Head NeckSurg 1988; instruction section, course 548.

123. Causse JB, Causse JR, Lopez A, et al. The relation of eusta-chian tube function, otosclerosis, and its surgery. Pre-sented at the Conference on the Eustachian Tube andMiddle Ear Disease. Geneva, 1989.

124. Gherin S, Causse JB, Griffin G. Gherini-Causse endo-otoprobe and HGM argon laser: applications in surgery formiddle ear defects. Presented at the International Confer-ence on Long-Term Results and Indications in Otology andOtoneurosurgery. France, 1990.

125. Palve T. Argon laser in otosclerosis surgery. Acta Otolaryn-gol 1987;104:153–157.

126. Ricci T, Mazzoni J. Experimental investigation of tempera-ture gradients in the inner ear following argon laser expo-sure. J Laryngol Otol 1985;99:359–362.

127. Gherini SG, Horn KL. Letter to editor. Laryngoscope 1990;100:209–211.

128. Nissen AJ. Laser applications in otologic surgery. ENT J1995;74:477–482.

129. Bartels L. KTP Laser stapedotomy: is it safe? OtolaryngolHead Neck Surg 1990;103:685–692.

130. Monsell EM, Balkany TA, Gates GA, et al. Committee onhearing and equilibrium guidelines for the diagnosis andevaluation of therapy in Meniere’s disease. OtolaryngolHead Neck Surg 1995;113:181–185.

131. Møller AR. Neurophysiological Basis of the Acoustic Middle-Ear Reflex. New York: Academic Press, 1984.

132. Colletti V, Sittoni V, Fiorino FG. Stapedotomy with andwithout stapedius tendon preservation versus stapedec-tomy: long–term results. Am J Otol 1988;9:136–141.

133. von Bekesy GV. Experiments in Hearing. New York: McGrawHill, 1960.

134. Vlaming MSMG, Feenstra L. Studies on the mechanics of thenormal human middle ear. Clin Otolaryngol 1986;11:353–363.

135. Pang XD, Peake WT. How do contractions of the stapediusmuscle alter the acoustic properties of the ear? Proceedings ofa Conference. Boston, MA: Boston University, 1985:36–43.

136. Bottrill ID, Poe DS. Endoscope-assisted ear surgery. Am JOtol 1995;16:158–163.

137. Poe DS, Rebeiz EE, Pankratov MM, Shapshay SM. Tran-stympanic endoscopy of the middle ear. Laryngoscope1992;102:993–996.

138. Esenaliev RO, Oraevsky AA, Letokhov VS, Karabutov AA,Malinsky TV. Studies of acoustical and shock waves in thepulsed laser ablation of biotissue. Lasers Surg Med 1993;13:470–484.

139. Czurko A, Toth Z, Doczi T, Gallyas F. Intracranial pressurewaves generated by high-energy short laser pulses cancause morphological damage in remote areas: comparisonof the effects of 2.1-mm ho:YAG and 1.06-mm nd:YAG laserirradiations in the rat brain. Lasers Surg Med 1997;21:444–455.

140. Luz GA. Recovery from impulse noise induced TTS in mon-keys and men: a descriptive model. J Acoust Soc Am 1971;49:1770–1777.

141. Shapshay SM, Rebeiz EE, Bohigian RK, Hybels RL, AretzHT, Pankratov MM. Holmium:yttrium aluminum garnetlaser-assisted endoscopic sinus surgery: laboratory experi-ence. Laryngoscope 1991;101:142–149.

142. Shapshay SM, Rebeiz EE, Pankratov MM. Holmium:yttriumaluminum garnet laser-assisted endoscopic sinus surgery:clinical experience. Laryngoscope 1992;102:1177–1180.

143. Pfalz R, Hibst R, Bald N. Suitability of different lasers foroperations ranging from the tympanic membrane to thebase of the stapes (Er:YAG, argon ion, CO2 s.p.,Ho:YAGlaser) [in German]. Laryngorhinostologie 1995;74:21–25.

144. Nuss RC, Fabian RL, Sarkar R, et al. Infrared laser boneablation. Lasers Surg Med 1988;8:381–391.

145. Shah UK, Poe DS, Rebeiz EE, Perrault DF Jr, PankratovMM, Shapshay SM. Erbium laser in middle ear surgery: invitro and in vivo animal study. Laryngoscope 1996;106:418–422.

146. Li ZZ, Reinisch L, Van De Merwe WP. Bone ablation wither:YAG and CO2 lasers. Lasers Surg Med 1992;12:79–85.

147. Frenz M, Romano V, Pratisto H, et al. Stapedotomy: newresults of the erbium laser. ORL Aktuelle Probl Otolaryn-gol 1994;17:335–343.

148. Ith M, Pratisto H, Altermatt HJ, et al. Dynamics of laser-induced channel formation in water and influence of pulseduration on the ablation of biotissue under water withpulsed erbium-laser irradiation. Appl Physiol B 1994;59:621–629.

149. Pratisto H, Frenz M, Ith M, et al. Temperature and pressureeffects during erbium laser stapedotomy. Lasers Med Surg1996;18:100–108.

150. Varvares MA, Brown MC, Liberman MC, Fabian RL. Appli-cation of the er:YAG laser to middle ear surgery: pressureeffects. Technical Digest Conference on Lasers and Electro-Optics: CLEO 94. 1994;8:1–7.

151. Jovanovic S, Anft D, Schonfeld U, Berghaus A, Scherer H.Experimental studies on the suitability of the erbium laserfor stapedotomy in an animal model. Eur Arch Otorhino-laryngol 1995;252:422–427.

152. Jovanovic S, Schonfeld U, Prapavat V, et al. Effects of pulsedlaser systems on stapes footplate. Lasers Surg Med 1997;21:341–350.

153. Lesinski SG. Lasers for otosclerosis: which one if any andwhy. Lasers Surg Med 1990;10:448–457.

154. Jovanovic S, Schonfeld U. CO2-laser applikationsarten in derstapeschirurgie. Proceedings of the 12th International Con-gress Laser ’95: Lasers Med. Berlin: Springer, 1996:328–331.

155. Nagel D. The er:YAG laser in ear surgery: first clinicalresults. Lasers Surg Med 1997;21:79–87.

156. Goldberg RA, Berliner KI. Reporting operative hearing re-sults: does choice of outcome measure make a difference?Am J Otol 1995;16:128–135.

157. Bottrill I, Perrault DF Jr, Pankratov MM, Poe DS. Thulium:YAG laser for stapes surgery: preliminary observations.SPIE Int Soc Optical Eng 1994;2128:23–30.

158. Wyman DR, Schatz SW, Maguire JAC. Comparison of 810nm and 1064 nm wavelengths for interstitial laser photo-coagulation in rabbit brain. Lasers Surg Med 1997;21:50–58.

159. Silverstein H, Bendet E, Rosenberg S, Nichols M. Revisionstapes surgery with and without a laser. Laryngoscope1994;104:1431–1438.

160. Liberman CM, Gao WY. Chronic cochlear de-efferentationand susceptibility to permanent acoustic injury. Hear Res1995;90:158–168.

161. Hough JVD. Partial stapedectomy. Ann Otol Rhinol Laryn-gol 1960;69:571–596.

162. Ricci T, Mazzoni M. Experimental investigation of temper-ature gradients in the inner ear following argon laser ex-posure. J Laryngol Otol 1985;99:359–362.


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Laser-Assisted Endoscopic Stapedectomy