Safety and efficacy of the endoscopic modified Lothrop procedure: A systematic review and meta-analysis

The LaryngoscopeVC 2009 The American Laryngological,Rhinological and Otological Society, Inc.

Safety and Efficacy of the EndoscopicModified Lothrop Procedure: A SystematicReview and Meta-Analysis

Peter Anderson, MD; Raj Sindwani, MD, FACS

Objectives/Hypothesis: The endoscopic modi-fied Lothrop procedure (EMLP; also known as DrafIII or frontal drillout) has recently gained popularityas a minimally invasive alternative to frontal sinusobliteration. This systematic analysis was designed toassess the safety and efficacy of the EMLP.

Study Design: Literature review and meta-analysis.

Methods: We performed a search of all Englishstudies published from 1990 to 2008 that reportedresults from a minimum of five patients undergoingthe EMLP. Of the 33 papers reviewed, 18 studies (evi-dence level II-2 or II-3) containing data from 612patients met inclusion criteria.

Results: The most common indications forEMLP were chronic frontal sinusitis (75.2%) andmucocele (21.3%). Patients had an average age of47.9 years (range, 14–89 years) and were followed for28.5 months postoperatively. Only 20.3% of proce-dures were performed without image-guidance. Stentswere rarely used (6%). The rate of major and minorcomplications was <1% and 4%, respectively. Nodeaths were reported. A majority of patients were dis-charged within 24 hours. Postoperative endoscopicfindings, qualitatively reported in 394 patients, dem-onstrated frontal sinus patency or partial stenosis in95.9% at last follow-up. Where specifically assessed(n ¼ 430 patients), improvement in symptoms wasachieved in 82.2% of cases, with 16% reporting no sig-nificant change, and 1.2% reporting worsening ofsymptoms. The overall failure rate (requiring furthersurgery) of EMLP was 13.9% (85/612). Of the failures,

80% underwent revision EMLP, whereas 20% electedosteoplastic frontal sinus obliteration.

Conclusions: When performed by an experi-enced surgeon, EMLP is a safe and efficacious proce-dure that is well tolerated.

Key Words: Endoscopic modified Lothropprocedure, endoscopic frontal drill out, Draf IIIprocedure, frontal sinusitis, outcomes.

Laryngoscope, 119:1828–1833, 2009

INTRODUCTIONDespite advances in medical and surgical therapy,

chronic frontal sinusitis remains a difficult disease tomanage. For those patients unresponsive to medicaltherapy, a graduated surgical approach has been recom-mended.1 Frontal sinus obliteration, as popularized byMontgomery in the 1950s, has long been considered thefinal tier surgery for refractory frontal sinusitis. Thisoperation is performed through an osteoplastic flap(OPF) approach and renders the sinuses permanentlynon-functional by obliterating them with fat or othermaterial. Although frontal sinus obliteration has a highsuccess rate of 93% at 8 years2 the rate of major compli-cations is also relatively high, occurring in over 20% ofpatients.3 These complications, mostly related to misdir-ected osteotomies extending beyond the confines of thefrontal sinuses,4 include dural exposure, dural lacerationwith cerebrospinal fluid (CSF) leak, and orbital injury.3

Postoperative issues can include forehead numbness,embossment and pain, osteomyelitis of the frontal boneflap, and mucocele formation.5

With the recent proliferation of endoscopic surgicaltechniques, minimally invasive procedures aimed atrestoring physiologic ventilation and drainage whileavoiding the morbidity of obliteration surgery have beendeveloped. Draf,6 Gross,7 and Close8 all described anendonasal, endoscopic approach similar conceptually tothat described by Lothrop in 1914, in which a combinedexternal and intranasal technique was used to resect thefrontal sinus floor and septum. The endoscopic modifiedLothrop procedure (EMLP), also known as the Draf IIIor bilateral frontal drillout procedure, creates a large

From the Department of Otolaryngology–Head & Neck Surgery,Saint Louis University, Saint Louis, Missouri, U.S.A.

Editor’s Note: This Manuscript was accepted for publication May5, 2009.

Presented at the Triological Society Combined Southern and Mid-dle Sections Meeting, Bonita Springs, Florida, U.S.A., January 8–11,2009.

Winner of the 1st Place Research Poster Prize.

Send correspondence to Raj Sindwani, St. Louis University Hospi-tal, Dept. of Otolaryngology, 3635 Vista Ave, 6 FDT, St. Louis, MO63110. E-mail: [email protected]

DOI: 10.1002/lary.20565

Laryngoscope 119: September 2009 Anderson and Sindwani: Safety and Efficacy of the EMLP

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common drainage pathway for the paired frontal sinusesby resecting the upper nasal septum, the interfrontalsinus septum, and the floor of both sinuses. Prior to thedescription of the EMLP, patients failing conservativeendoscopic procedures would have their sinuses obliter-ated. The EMLP has developed as another minimallyinvasive option, before the final step of frontal oblitera-tion is considered. Compared to the gold standard ofobliteration, the EMLP offers the advantages ofdecreased morbidity, shorter hospital admission withlower costs,9 improved cosmesis, reduced blood loss, andpreservation of a functional frontal sinus with superiorability to survey for recurrent disease both endoscopi-cally and radiographically.3 Complications of the EMLPinclude: dural injury and CSF leak, orbital injury, andinjury to the nasal bones and skin.5

Although gaining popularity as an alternative tofrontal obliteration, the utility of this relatively new pro-cedure has not yet been established. The purpose of thisstudy was to systematically examine the literature andevaluate the safety and efficacy of the EMLP. We soughtto delineate indications and contraindications for thissurgery, to assess both subjective and objective out-comes, and to determine the complication and failurerates of the EMLP. In addition, we evaluated the impactof a variety of technical factors (such as the use ofimage-guidance, stenting, etc.).

MATERIALS AND METHODS

Study Selection and Data ExtractionAll published studies from January 1990 to May 2008

were identified by searching MEDLINE, the Cochrane data-base, and multiple additional medical databases with the

search terms ‘‘endoscopic modified Lothrop procedure,’’ ‘‘DrafIII,’’ and ‘‘frontal sinus drillout procedure.’’ We identified 33publications. Both authors independently performed a thoroughreview of all publications using the guidelines provided by theMeta-Analysis of Observational Studies in Epidemiology state-ment for evaluating observational studies. The followingcharacteristics of the studies and the participants were system-atized using the participant, intervention and exposure,comparator, outcomes, and study design approach: author, year,design, participants, surgical procedure, duration, purpose, sur-vey methods, and specific symptoms analyzed.

Exclusion criteria were designated as papers with dataregarding animal studies, cadaver studies, case reports of lessthan five patients, and reports not in the English language.Exclusions were also made due to duplicate publication of dataencountered in the literature and results from unilateral proce-dures. A database was then established that contained dataregarding patient population (age, gender, comorbidities, priormedical and surgical treatments), preoperative workup, opera-tive techniques, and postoperative results.

RESULTS

EpidemiologyOf the 33 papers reviewed, 18 studies (9 level II-2

and 9 level II-3 evidence) containing data from 612patients met inclusion criteria and comprised this reviewand meta-analysis (Fig. 1). Table I highlights the charac-teristics of the studies.

The average patient age was 47.9 years (range, 14–89 years), and the male to female ratio was found to be1:0.83. Patients had undergone an average of 4.8 � 1.7

Fig. 1. Study selection flow-chart. EMLP ¼ endoscopic modifiedLothrop procedure.

TABLE I.Characteristics of Studies.

SourceSampleSize

AverageFollow-up,

mo

Failures(RevisionSurgery)

OutcomesMeasured

Gross et al., 19957 10 7 0 O

Gross et al., 19979 20 12 0 SþO

Metson & Gliklich, 199824 9 22.7 0 S

Kikawada et al., 199925 16 24.7 0 O

Ulualp et al., 200010 15 2 S

Schulze et al., 200226 13 34.5 2 O

Schlosser et al., 200227 54 40.3 17 SþO

Samaha et al., 200316 66 49.2 10 S

Stankiewicz & Wachter,200328

10 34 5 S

Wormald et al., 200317 16 18.9 1 SþO

Wormald & Chan, 200311 13 0 SþO

Wormald et al., 200314 14 25 3 SþO

Wormald, 200319 83 21.9 6 SþO

Khong et al., 200412 21 2 S

Banhiran et al., 200615 72 22 5 SþO

Tran et al., 200713 77 29.2 10 O

Shirazi et al., 200729 97 18 22 S

Nakagawa & Ito, 200730 6 24.5 0 SþO

Three studies did not report average follow-up for the endoscopicmodified Lothrop procedure, specifically.22,26,28 S ¼ subjective outcomes,O ¼ objective outcomes.


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prior sinus surgeries (range, 1–19 procedures) before theEMLP was pursued. The most common indications forthe EMLP in 612 patients were chronic frontal sinusitis(75.2%) and mucocele (21.3%). As displayed in Table II,less common indications were tumors such as invertedpapilloma, frontal osteoma, and esthesioneuroblastoma.The most common reported comorbidities in patientsundergoing EMLP were nasal polyposis (26.8%), asthma(6.4%), allergic rhinitis (5.1%), and laryngopharyngealreflux (2.6%).

Preoperative Evaluation and Surgical DetailsPreoperatively, all patients had a sinus computed

tomography (CT) scan. Studies using the Lund-MacKayCT staging system reported an overall average score of11.8 (range, 3–21), and an average frontal sinus score of1.61 (range, 1–2). Reports utilizing the Harvard stagingsystem classified the majority of patients as stage III(70.1%), with 16.1% reported as stage IV, and 12.9% asstage I. The majority of procedures (79.7%) were per-formed utilizing image-guidance. The technique ofstenting the enlarged frontal opening was rarely used(6% of cases). Almost all EMLP patients (>99%) weredischarged home within 24 hours after surgery. Reportedcomplications were divided into major and minor catego-ries, displayed in Table III. The rate of major and minorcomplications was <1% and 4%, respectively. There wereno deaths reported. The average documented follow-up

for the study group was 28.5 months (range, 1–90months). Three studies did not report average follow-upfor the EMLP specifically.10–12 Two of these listed anoverall follow-up period, which included patients whounderwent procedures other than the EMLP,11,12 and apaper by Ulualp et al.10 reported only a follow-up rangefor EMLP patients (0.5 months–2.5 years) without pro-viding an average or median.

OutcomesThe methods of measuring surgical outcomes var-

ied, with only eight of 18 studies reporting bothsubjective and objective parameters (Table I). Objectiveevaluation via postoperative endoscopic findings wasreported in only 394 patients (12 studies). In thesepatients, direct endoscopic examination of the frontalneo-ostium revealed patency (or partial stenosis) in95.9% at last follow-up (Fig. 2). Most studies noted thatthe stenosis of the neo-ostium occurred within the firstyear following the surgery. Fourteen studies provided in-formation on symptomatic outcomes following EMLP.Subjective evaluation via survey of symptom improve-ment was reported for 430 patients. As illustrated inFigure 3, 82% of these subjects reported significantimprovement or total resolution of their frontalsymptoms, 16% reported no significant change, and1.2% reported an actual worsening of their symptoms

TABLE II.Indications for Endoscopic Modified Lothrop Procedure.

Indication No. of Patients (n¼612)

Chronic frontal sinusitis 464

Mucocele 123

Inverted papilloma 6

Frontal osteoma 5

Esthesioneuroblastoma 7

Trauma 7

TABLE III.Complications of the Endoscopic Modified Lothrop Procedure.

Complication No. of Cases

Major (<1%)

CSF leak 2

Tension pneumocephalus 1

Posterior table dehiscence 1

Minor (4%)

Increased crust formation 9

Epistaxis 8

Anosmia/hyposmia 5

Nasal bone dehiscence 2

Philtral pressure ulcer 1

Transient blurry vision 1

Fig. 2. Objective outcomes from endoscopic modified Lothropprocedure.

Fig. 3. Subjective outcomes from endoscopic modified Lothropprocedure.


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post-EMLP. Of the 1.2% of patients reporting worseningsymptoms, it was not clearly stated which symptomsspecifically worsened following surgery. Details ofwhether there was a worsening of existing symptoms orthe introduction of new complaints were not provided.

The overall surgical success rate of the EMLP isillustrated in Figure 4. In our review, we classified fail-ure of the EMLP as the need for any revision surgery onthe frontal sinuses. By this definition, the failure rate ofthe EMLP was 13.9% (85 of 612 patients). Of the 85patients who underwent further surgical treatment, 80%had a revision-EMLP and 20% elected to have osteoplas-tic frontal sinus obliteration. The parameters used todecide which option (revision-EMLP vs. obliteration) waspursued in any individual patient were not reported byany study. Most studies did not report a difference insurgical outcomes based on indication for surgery. Tranet al.13 studied the effects of numerous comorbidities onostium restenosis, such as allergy, asthma, aspirin sensi-tivity, gastroesophageal reflux disease, nasal polyposis,and eosinophilic mucin chronic rhinosinusitis (EMCRS).Of these factors, the diagnosis of EMCRS was the onlyone that correlated with an increased rate of ostial reste-nosis. Wormald et al.14 also reported higher rates ofrestenosis and revision surgery in patients with diseasebreaching the confines of the frontal sinus walls andextending into the cranial cavity and orbit. It should benoted, however, that even in the setting of extensive dis-ease, the EMLP offered comparable results to thoseachieved with external approaches.

DISCUSSIONThe variable anatomy of the frontal outflow tract

and close proximity of the orbit and skull base make theEMLP a technically demanding operation.1 The largeconduit into the frontal sinuses is created using angledendoscopes and specialized powered instrumentation,which further add to the complexity of this procedure.Despite this, our findings demonstrated that the EMLPis a safe and well-tolerated procedure with a very low

risk of major complications (<1%) when performed byexperienced surgeons.

In this analysis, the EMLP was shown to be highlyefficacious in the treatment of refractory frontal sinusdisease, based on subjective symptom improvement,objective endoscopic evaluations of frontal patency, andthe need for further surgery. The overall failure rate ofEMLP was calculated to be only 14% in this large cohortof patients. Moreover, many of the failures (80%) wenton to have a revision-EMLP performed in lieu of obliter-ation. It is important to emphasize that patients whofail the EMLP are still amenable to traditional means offrontal sinus obliteration. Unfortunately, the parametersused to decide which procedure is preferred in cases offailure and why, were not addressed by the literature.Stents are rarely used after the EMLP, and they do notappear to reduce the rate of postoperative stenosis.15

Image-guidance is preferred by most surgeons perform-ing this operation, although its application has not beenshown to improve outcomes.16 As highlighted in severalof the articles comprising this review, image-guidancemay be beneficial, but an intimate understanding of theanatomy of the frontal outflow tract is paramount inavoiding complications.

The outcomes observed in our study were based onan average follow-up of over 2 years, with some datasupporting that most of the significant stenosis of theneo-ostium portending eventual failure of the procedureoccurs within the first 12 months postsurgery.17

Although long-term results are required, the current lit-erature suggests that the EMLP offers a success ratesimilar to OPF obliteration surgery with far less morbid-ity.16 This success rate may actually be augmented ifrevision attempts at the EMLP in cases of initial failureare included. Further inquiry with long-term follow upis also needed to establish whether the creation of sucha large aperture with removal of intervening bony septa-tions within the frontal sinuses (which is not strictlyphysiologic) has any deleterious effects on mucociliaryclearance.

Interest in the minimally invasive management offrontal sinus disease by avoiding the OPF approach isnot new. Ung et al.18 described a novel technique ofendoscope-assisted frontal sinus obliteration via a tre-phine. However, the procedure, which lacks long-termfollow-up, was only advocated for a highly selected groupof patients with a unilaterally diseased, small frontalsinus with simple topography. The indications for theEMLP appear generally similar to those for OPF obliter-ation, with the most common reasons for surgery beingchronic refractory frontal sinusitis and mucocele. Inter-estingly, failed cases of OPF obliteration can also berescued and successfully managed with the EMLP.17

Contraindications to the EMLP include absent frontalsinuses, unfavorable intranasal anatomy, most notably anarrow anteroposterior diameter between anterior skullbase and frontal beak, a noncompliant patient, and lackof familiarity with advanced techniques.19 In addition, ithas been suggested that EMLP may not be appropriatewhen disease involves the most lateral recesses of awell-pneumatized frontal sinus,20,21 or if there is

Fig. 4. Surgical outcomes and revision procedures. EMLP ¼ endo-scopic modified Lothrop procedure.


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osteomyelitis of the frontal bone requiring significantbone removal.20 Recent trends also suggest that theabsolute contraindication to frontal obliteration of exten-sive erosion of the posterior table of the frontal sinus(necessitating instead frontal sinus cranialization, due todifficulty with complete extirpation of mucosa) is not acontraindication to endoscopic techniques such as theEMLP.22

A few years after the EMLP was described, an anal-ysis of the procedure was sanctioned by the RoyalAustralasian College of Surgeons and published in2001.5 This review included only a few studies with avery small number of patients, and as a result, thegroup reported that the available data at the time onthe EMLP was inadequate to comment upon its merits.The EMLP is still not a commonly performed surgery.Improved facility with more conventional endoscopicsinus techniques, and the application of image-guidancetechnology, has significantly enhanced our ability to per-form successful frontal sinus surgery.23 The technicalnature of the EMLP is in contrast to the OPF oblitera-tion procedure, which is a simpler operation that mostgeneral otolaryngologists are quite familiar with. Inlight of these realities, it is unlikely that the EMLP willbe a procedure used by many otolaryngologists for sometime. It is expected that traditional frontal sinus obliter-ation will continue to play a role as a solid surgicaloption for difficult to manage frontal sinus disease. TheEMLP will likely serve as an intermediate step betweenconventional endoscopic frontal approaches and frontalsinus obliteration, but only for those comfortable withthis procedure.

This study possesses all of the limitations associ-ated with the meta-analysis of retrospective studies:incomplete data, problematic interpretation of some in-formation, publication bias, etc. Despite best efforts weare reviewing in aggregate studies that may be quite dif-ferent in design, surgical techniques, surgeonexperience, etc. (apples and oranges argument). Accept-ing these inherent flaws, this analysis demonstratedthat the EMLP is a safe and efficacious procedure.Patients who are doing well one year postsurgery tendto have favorable long-term outcomes.

CONCLUSIONThis analysis demonstrated that the EMLP is a

highly effective option for the surgical treatment ofchronic frontal sinusitis. When performed by an experi-enced surgeon, the EMLP is a safe and well-toleratedprocedure, with low complication and failure rates.Although technically demanding, the EMLP offersmarked advantages over frontal sinus obliteration, andrepresents an attractive alternative to defunctioningsurgery.

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Safety and efficacy of the endoscopic modified Lothrop procedure: A systematic review and meta-analysis