STRABISMUS DUE TO FLAP TEAR OF A RECTUS MUSCLE* · 2016. 7. 19. · Tr. Am. Ophth. Soc. Vol. 99, 2001 53 STRABISMUS DUE TO FLAP TEAR OF A RECTUS MUSCLE* BY Irene H. Ludwig, MDAND

Tr. Am. Ophth. Soc. Vol. 99, 2001 53

STRABISMUS DUE TO FLAP TEAR OF A RECTUS MUSCLE*

BY Irene H. Ludwig, MD AND Mark S. Brown, MD (BY INVITATION)

ABSTRACT

Purpose: To present a previously unreported avulsion-type injury of the rectus muscle, usually the inferior rectus, anddetail its diagnosis and operative repair.

Methods: Thirty-five patients underwent repair of flap tears of 42 rectus muscles. The muscle abnormality was often sub-tle, with narrowing or thinning of the remaining attached global layer of muscle. The detached flap of external (orbital)muscle was found embedded in surrounding orbital fat and connective tissue. Retrieval and repair were performed ineach case.

Results: Fourteen patients had orbital fractures, 7 had blunt trauma with no fracture, and 9 had suspected trauma butdid not undergo computed tomographic scan. Five patients experienced this phenomenon following retinal detachmentrepair. Diagnostically, the predominant motility defect in 25 muscles was limitation toward the field of action of the mus-cle, presumably as a result of a tether created by the torn flap. These tethers simulated muscle palsy. Seventeen muscleswere restricted away from their field of action, simulating entrapment. The direction taken by the flap during healingdetermined the resultant strabismus pattern. All patients presenting with gaze limitation toward an orbital fracture hadflap tears. The worst results following flap tear repair were seen in patients who had undergone orbital fracture repairbefore presentation, patients who had undergone previous attempts at strabismus repair, and patients who experiencedthe longest intervals between the precipitating event and the repair. The best results were obtained in patients whounderwent simultaneous fracture and strabismus repair or early strabismus repair alone.

Conclusions: Avulsion-type flap tears of the extraocular muscles are a common cause of strabismus after trauma, and afterrepair for retinal detachment. Early repair produces the best results, but improvement is possible despite long delay.

Tr Am Ophth Soc 2001;99:53-63

INTRODUCTION

Diplopia following head or facial trauma is usually attrib-uted to palsy of a cranial nerve or its branch or to incar-ceration of an extraocular muscle in an orbital fracturesite. Restriction of eye movement by adhesions to scar tis-sue is also reported to contribute to strabismus.1-4

Generally, a lengthy delay (months) is advocated beforestrabismus surgery is undertaken.1-3,5-8 Repair may consistof ipsilateral muscle surgery and/or a procedure to limitexcursion in the nontraumatized contralateral eye9 to bal-ance the deficit in the injured one.

In a number of post-traumatic strabismus cases, aspecific type of avulsion injury to the rectus muscle(s) hasbeen identified and repaired. We propose a mechanismfor the development of the flap tear, which is consistent

with recently reported anatomic and functional studies ofthe extraocular muscles.

METHODS

SURGICAL APPEARANCE

Thirty-five patients underwent repair of avulsion-type injuriesof one or more rectus muscles. The involved rectus musclewas approached through a standard fornix incision and placedon a muscle hook at its insertion into sclera. The presence ofa flap tear was suggested by 3 different appearances:

1. A segment of muscle and tendon was missing,which narrowed the remaining portion of attachedmuscle (Fig 1).

2. The outer or orbital layer of muscle was missing,beginning at the musculotendinous junction andextending proximally (Fig 2). These musclesappeared thinned and lacked intact muscle cap-sule. The thinned area involved the entire width ofthe muscle in some and a smaller portion of muscle in others.

*From the Department of Ophthalmology, LSU Eye Center, LouisianaState University Health Sciences Center, New Orleans (Dr Ludwig) andthe Department of Ophthalmology, The University of South Alabama,Mobile (Dr Brown). Supported in part by an unrestricted departmentalgrant to the LSU Eye Center from Research to Prevent Blindness, Inc,New York, New York.

03 Ludwig Final 11/9/01 9:06 AM Page 53

54

Ludwig et al

3. The muscle was encased in adherent orbital fat,requiring careful dissection before disclosure ofthe avulsion injury, which could appear as either ofthe two previously described abnormalities.

In each of the 3 presentations, the torn “flap” of tissue wasfound external to the muscle, scarred into surroundingorbital connective tissue and fat (Fig 3). Sometimes sev-eral smaller flaps of muscle were found.

Forced duction testing was performed before andduring muscle repair in all cases. Restrictions both towardand away from the direction of the involved muscle’saction were often present. In some cases the forced duc-tion abnormality was subtle, and it only became evidentwhen the procedure was performed gently, with simulta-neous comparison to the uninjured contralateral eye.

SURGICAL REPAIR TECHNIQUE

The flap was placed on a small muscle hook and dissectedfree from its orbital attachments at the distal end. A braid-ed polyester suture was placed through the distal end ofthe flap, with standard strabismus locking bites (Fig 4).The flap was then attached to sclera at the original inser-tion, or back to the musculotendinous junction, as neces-sary to restore anatomy (Fig 5). The rent in overlyingTenon’s capsule, which was always present, was suturedwith 6-0 polyglactin after the protruding orbital fat wasreposited through the rent.

If the capsule of the repaired muscle appeared com-plete, it was repaired directly with buried 6-0 or 7-0polyglactin suture. In some cases, the capsule seemedpartly damaged. In these cases, a free graft of Tenon’s cap-sule was sutured over the traumatized surface of the mus-cle with running 7-0 polyglactin (Fig 6). The Tenon’s graftwas harvested from an uninvolved quadrant of the sameeye, usually superotemporally.

Postoperatively no steroids were used. Patients wereasked to exercise the muscle frequently by looking in andout of the field of muscle action to prevent adhesions fromre-forming between the flap and surrounding orbital con-nective tissue.

RESULTS

PATIENT CHARACTERISTICS

The mean age of the 35 patients at time of flap tear repairwas 40 years (range, 6 to 82 years). The mean delaybetween the date of injury and repair was 67 months(range, 2 weeks to 46 years). Mean postoperative follow-up was 9 months (range, 1 to 68 months). The left inferi-or rectus muscle was most commonly involved (22 cases)

followed by the right inferior rectus muscle (12), themedial rectus (6), and the superior rectus (2) (Table I).The predominance of affected left inferior rectus musclesis presumed to be related to the right-handedness ofassailants delivering the trauma in some cases.

PRECIPITATING EVENT

Fourteen patients had orbital fractures, and 6 had blunttrauma with documentation of the absence of fracture bycomputed tomographic (CT) scan. In 9 cases, the findingof flap tear was unexpected and orbital imaging was notundertaken. In most cases, a long time had elapsedbetween injury and repair. In 1 child, CT scan wasobtained following development of downgaze deficiency 1week after seemingly minor blunt trauma to the inferiororbital rim. There had been no external signs of the injuryat the time. He had posterior orbital floor fracture andinferior rectus flap tear (Fig 7).

Two patients had no specific history of orbital trauma.One patient had a normal CT scan and questionable,remote history of trauma. Five patients developed flaptears after retinal detachment repair (Table II).

DIAGNOSIS

Motility DefectsIn 20 patients, the motility defect was toward the direc-tion of action of the involved muscle, presumably as aresult of a tether created by the flap. Twelve of these pre-sented as downgaze deficiencies following documentedorbital floor fracture. In 10 patients the presenting deficitwas gaze restriction away from the field of action of themuscle, simulating persistent entrapment or muscle fibro-sis. One had paradoxical esodeviation on attemptedupgaze, along with limitation of elevation and depressionafter orbital floor fracture repair. One patient had 2involved muscles in 1 eye. The torn medial rectus causedexotropia with adduction limitation owing to the tethereffect, and the superior rectus tear led to hyperdeviationowing to a restrictive effect. Two patients had tears of bothinferior rectus muscles and 1 medial rectus muscle each.The inferior rectus muscles caused asymmetric downgazereduction owing to the tether effects, and the medial rec-tus muscle tears led to esotropia owing to restrictiveeffects. Another patient, with idiopathic etiology, hadbilateral inferior rectus flap tears, with mild upgazerestriction in 1 eye, and downgaze restriction in the other.There was no difference in the appearance of the flap tearor the difficulty of repair in terms of the various types ofmotility patterns. Our impression was that an anteriorattachment site of the flap led to a tether effect and a pos-terior flap position led to pseudo-entrapment.


Strabismus Due To Flap Tear Of A Rectus Muscle

55

FIGURE 1Flap tear of inferior rectus, narrowed type (same as in Fig 7A). Arrowindicates missing portion of muscle; hook is pulling on insertion ofremaining attached portion of muscle.

FIGURE 2Flap tear of medial rectus, thinned type, 2 months after retinal detach-ment repair. Open arrow indicates thinned remaining portion of muscle,lacking capsule. Solid arrow points to flap, which is pulled outward byretractor.

FIGURE 3Flap tear of inferior rectus, 20 years after motorcycle accident. Attachedportion of muscle is held by large hook (open arrow). Flap, held in smallhook, is adherent to surrounding orbital tissue (solid arrow).

FIGURE 4AInferior rectus flap (same patient as in Figs 1, 6, and 7), dissected free,and placed on 6-0 braided polyester suture. Lock bites indicated byarrows.

FIGURE 4BInferior rectus flap, thinned type. Flap is held on braided polyestersuture (solid arrows). Hook (open arrow) holds attached, inner portionof muscle.

FIGURE 5Medial rectus from Fig 2, after flap reattachment. Arrow indicates cen-tral knot in suture.


56

Preoperative DiagnosisFive patients were misdiagnosed preoperatively as havingfourth cranial nerve palsy, 2 as having Brown’s syndrome,and 1 as having sixth cranial nerve palsy. In the firstpatient treated (MC), a lost inferior rectus was suspectedbecause of the absence of downgaze. Many of thesepatients would have qualified as having isolated palsy of

the inferior rectus based on measurements alone.Preoperative force generation testing was useful to rule

out nerve palsy. Although restricted in excursion of move-ment, the involved muscles showed normal strength.Forced duction testing was usually performed immediatelybefore surgery, with the patient under paralytic anesthesia.

Since the first case was identified in 1994, everypatient presenting to this practice with a preoperativediagnosis of orbital fracture together with limitation ofmotility toward the direction of the fracture was found tohave a flap tear.

SURGERY

Sixteen patients underwent direct repair of the flap alone,with no other muscle surgery (Table III). Two of theserequired re-repair of the flap: 1 for a small residual flapsegment that had been missed at the initial procedure,

TABLE I: INVOLVED MUSCLES

NO. OFMUSCLES NO. OFINVOLVED PATIENTS MUSCLE

LEFT RIGHT MEDIAL SUPERIOR

INFERIOR INFERIOR RECTUS RECTUS

RECTUS RECTUS

1 30 19 8 2 12 3 1 2 2 13 2 2 2 2 0

FIGURE 6Repaired inferior rectus (same as in Figs 1 and 4a), with overlying Tenon’sgraft. Tenon’s fibers are oriented 90° from muscle and tendon fibers.

FIGURE 7ACT scan showing posterior orbital fracture with inferior rectus entrap-ment (arrow). (Patient’s inferior rectus is seen in Figs 1, 4a, and 6.)

FIGURE 7BPreoperative (left) and postoperative (right) motility of 6-year-old boywho underwent simultaneous repair of orbital floor fracture and inferi-or rectus (Figs 1, 4a, and 6) flap tear 2 months after minor blunt trauma.

TABLE II: PRECIPITATING EVENT

CAUSE OF STRABISMUS NO. OF CASES

Orbital fracture 14Blunt trauma, no fracture 5Trauma, possible fracture 10Retinal detachment 5Idiopathic 1

TABLE III: PRIMARY SURGERY

REPAIR OF REPAIR OF FLAP SURGERY ON

FLAP ONLY PLUS RECESSION ADDITIONAL

OR RESECTION MUSCLES

OF SAME MUSCLE

Total cases 16 4 15No. requiring 2 1 5second procedure

Ludwig et al


57

TAB

LE

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CL

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AO

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PAT

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58

Ludwig et alTA

BL

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2487

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poss

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with

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air

bag

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yes

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yes

LH

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2-de

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Res

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552

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yes

fell

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LH

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yes

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72-

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3326

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563

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1.5

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5,no

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4-de

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tho

3-de

pr O

S2

bat

LL

R6



59

and the other for a complete flap redetachment. Theredetachment was thought to have occurred as a result ofthe child’s failure to move the eye postoperatively, as wellas damage to the muscle capsule and, possibly, loss ofstrength of the absorbable suture used to reattach themuscle. At reoperation, the flap was reattached with non-absorbable suture and a Tenon’s graft was placed. The sec-ond repair was successful. Nonabsorbable suture has beenused for flap reattachment in all subsequent cases.

Forced duction and spring-back testing10 were used todetermine whether flap tear repair alone relieved the gazerestriction and centered the eye. If not, additional surgerywas undertaken.

Additional Strabismus SurgeryFifteen patients underwent simultaneous surgery onother extraocular muscles, and 7 of these required a sec-ond strabismus procedure. Four patients exhibited resid-ual restriction of motility away from the direction of actionof the muscle with the flap repair, and they underwentsimultaneous recession of that muscle alone during theinitial surgical procedure. Surgery on additional muscleswas needed more often when a longer time had elapsedbetween injury and repair. Secondary deviations wereconsidered and corrected; the most common was ipsilat-eral lateral rectus recession for exotropia.

Orbital Fracture RepairSix patients had undergone orbital fracture repair prior toflap tear repair, and 3 underwent repair of muscle andorbit on the same day by a strabismus surgeon (I.H.L.)and an ophthalmic plastic surgeon (M.S.B.). These 3 casesconfirmed the impression that the flap tear is remote fromthe fracture site and is not the result of bony impingementon the muscle. Five patients with documented fracturesdid not undergo fracture repair.

POSTOPERATIVE ALIGNMENT

Preoperative and postoperative alignment data were notanalyzed statistically for the group owing the heteroge-neous population of involved muscles and variety of addi-tional muscle surgeries performed (Table IV). Of the 16patients who underwent flap tear repair alone, all wereimproved, most achieved resolution of diplopia duringregular activities, and 9 had normal alignment in all gazepositions.

The best results were achieved in those who under-went simultaneous repair of flap tear and orbital fractureand those who did not undergo fracture repair. The worstresults occurred in those who had undergone previousorbital fracture repair (MC, CH, SL, TL, KM, AW) and/orstrabismus surgery (RB, MC, TL, MS, FS). One patient

(CH) had undergone 2 orbital surgeries because of thepersistent downgaze deficiency. He had severe motilityrestriction noted during subsequent flap tear repair, andalthough the primary position alignment was restored,motility remained poor.

Long delay from injury to repair seemed to worsenthe prognosis for some patients, but others did welldespite the lapse of many years. Those with smaller flapsand smaller preoperative deviation of alignment hadimproved chance of resolution with flap-tear repair alone.Greater delay to treatment increased the likelihood of fur-ther surgery on additional muscles. No patient was wors-ened by flap tear repair (Table IV).

CASE REPORTS

Case 1A 12-year-old boy developed diplopia after striking hisright inferior orbital rim on the handle of a bicycle. In theprimary position he had a right hyperdeviation of 14 prismdiopters (D), which increased to 20D on downgaze.Elevation and depression of the right eye were markedlyreduced (Fig 8, left). CT scan showed a narrow orbitalfloor fracture in the medial portion of the orbital floor,with entrapped orbital tissue and muscle. Orbital fractureand strabismus repairs were undertaken at the same time,3 weeks after injury, by the authors.

Forced duction testing showed restriction to eleva-tion and depression in the right eye. The fracture site wasapproached via standard transconjunctival incision.Significant herniated orbital fat and connective tissuewere present, and entrapped inferior rectus tissue wasidentified in the posterior aspect of the fracture (Fig 9).After the tissues were lifted out of the fracture, repair wasmade with porous high-density polyethylene barriersheet, and the wound was closed. The inferior rectus wasthen exposed through a standard inferotemporal fornix

FIGURE 8Case 1. Preoperative (left) and postoperative (right) motility.


60

Ludwig et al

incision. The flap tear was identified by the narrowedappearance of the muscle (Fig 10) and repaired as alreadydescribed (Fig 11), including free Tenon’s graft. The tornsegment of muscle was markedly anterior to the entrappedportion and was clearly distinct and separate from thefracture site. Postoperatively, downgaze graduallyimproved, and 6 weeks later motility was normal, withorthotropia in all directions of gaze (Fig 8, right).

Case 2A 36-year-old policeman was hit on the back of the headand fell forward, striking his face on the pavement. Hesuffered a brief loss of consciousness. When he becameaware of his surroundings in the hospital on the next day,he noticed vertical diplopia. An imaging study of the headwas reported to be normal. Twelve days later he present-ed for strabismus evaluation. Alignment was esophoria of4� in the primary position, and left hypertropia of 16�with esotropia 4� in downgaze. The hyperdeviation wasabsent on right head tilt, and 6� on left head tilt. Leftfourth cranial nerve palsy was diagnosed by a strabismussurgeon (I.H.L.) as well as by a neuro-ophthalmologist.There was no improvement by 2 months after injury, andno torsion was found with subjective testing or fundusexamination.

The patient recalled that the left lower lid was ecchy-motic after the injury. High-resolution magnetic reso-nance imaging of the orbits and brain, with particularattention to the left inferior rectus, was obtained, but noabnormality could be detected. Nine weeks after injury,he underwent exploration of the left inferior rectus via aninferotemporal fornix incision. A flap tear was found, withthinning of the muscle proximal to the musculotendinousjunction and absence of capsule. The repair included clo-sure of the overlying rent in Tenon’s capsule. One weekafter surgery, alignment was orthotropia in primary posi-tion with left hypertropia of 10� in downgaze. Five weeks

after surgery, the patient was orthotropic in all directionsof gaze. Two years later he remains orthotropic in alldirections.

DISCUSSION

Orbital trauma has been associated with a range of sever-ity of ocular injuries.11-13 Posttraumatic strabismus has tra-ditionally been attributed to direct muscle contusion by anorbital fracture site, orbital hematoma, or nerve damage.1-8 Spontaneous improvement in diplopia has been report-ed,1,5,6,8,14 and patients are usually asked to wait for sometime before strabismus repair is considered.1-8 Orbital sur-gery to relieve entrapment is usually undertaken if diplop-ia persists after 2 to 3 weeks.6,8 Strabismus repair is thennot considered before 4 to 6 months.1-8 Strabismus proce-dures that have been advocated include ipsilateral rectusresection and recession,3 contralateral superior obliquerecession,3 rectus muscle transposition procedures,8 andthe Faden operation to the contralateral eye.9

Since we observed the presence of flap tears withoutorbital fracture, as well as the findings in 3 cases in whichorbital and muscle repairs were concurrent, we believethat the avulsion was a related, but separate, finding dueto the original trauma.

Recent anatomic studies of the extraocular muscleshave shown 2 distinct layers: (1) the global layer, adjacentto the globe, and (2) the orbital layer, which lies external-ly. The orbital layer has also been shown to be surround-ed by dense connective tissue and penetrated by elastin,which effectively inserts the orbital layer of the rectusmuscle into the orbital connective tissue.15

We hypothesize that the sudden downward force expe-rienced by the orbital contents at the time of blunt traumamay exert traction on the connective tissue insertion intothe orbital layer of the muscle, tearing the outer layer awayfrom the inner, global layer (Fig 12). This mechanismcould result in the thinned-type appearance of the flap-tearmuscle. Other flap tears presented with a narrowedappearance of the muscle, with a full or partial thicknessdefect of the remaining attached portion of muscle. Thesemay have experienced asymmetric avulsion force, leadingto asymmetric flaps. The force might possibly be transmit-ted to the muscle from the side by the intermuscular sep-tum, which would also produce flap asymmetry.

Perhaps the 2 muscle portions may reunite duringhealing; this would explain the cases of spontaneousimprovement that have been reported.1-8 Motility findingsvary according to the healing pattern of the flap tear. If theflap heals anteriorly, creating a tether, the predominantdefect would be a loss of function of the involved muscle(Fig 13). Tether-type motility defects are reported tooccur in about one third of orbital floor fractures with

FIGURE 9Case 1. Orbital fracture (arrow).



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vertical diplopia14 and have also been reported with medi-al wall fractures.16 A small tether effect of an inferior rec-tus flap tear could mimic ipsilateral fourth cranial nervepalsy. This was seen in 5 of our patients, and a similarmotility pattern after floor fracture has been reported.1,17

A posteriorly healed flap would lead to restriction of gazeaway from the site of injury, which was also common.Restrictive strabismus was reported in two thirds of floorfracture patients with vertical diplopia.14 An intermediateflap location could allow unimpeded motility. This isanother possible explanation for spontaneous improve-ment of diplopia in some orbital fracture patients.Horizontal abnormalities resolved in several patients afterflap tear alone, suggesting that horizontally directed adhe-sions might have contributed to the strabismus.

On the basis of our experience with this series ofpatients, we believe that a tether-type of motility defect isdiagnostic of flap tear. Downgaze deficiency after orbital

floor fracture has been attributed to palsy of the inferiorbranch of the third cranial nerve,1-3 but in our series allcases with downgaze deficiency after ipsilateral orbitalfloor trauma had flap tears. The unexpected finding ofidentical tears in patients with long-standing strabismus,some of whom remembered the trauma only after carefulquestioning, is of interest. The trauma was sometimesuneventful and not immediately apparent. After onelearns to recognize the abnormally narrowed or thinnedrectus muscle with missing capsule, the defect becomesreadily apparent in many cases. A completely restoredmuscle capsule confirms that repair is complete. This waseven possible in cases repaired many years after injury.

Five patients had flap tears after retinal detachmentrepair. Perhaps the retinal surgeon’s practice of bluntlystripping connective tissue off the extraocular muscle maypull away a flap of muscle tissue and lead to postoperativestrabismus.

FIGURE 10Case 1. Inferior rectus showing narrowed type of flap tear. Missing por-tion indicated by open arrows. Flap is held on small hook (solid arrow).

FIGURE 11Case 1. Repaired inferior rectus, with Tenon’s graft.

FIGURE 12Drawing indicating hypothesized traction on inferior rectus outer layerdue to orbital fracture, causing avulsion.

FIGURE 13Drawing indicating anterior flap position after injury, which would cre-ate a tether.


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Immediate and regular eye exercise postoperatively isimportant to prevent adhesions from re-forming betweenthe muscle and orbital connective tissue. The free Tenon’sgraft and repair of the overlying rent in Tenon’s capsulealso may help to reduce adhesions. Nonabsorbable sutureis always used to reattach or anchor the flap to sclera.

On the basis of the findings in these patients, it is rec-ommended that all orbital fracture patients with diplopiawho are to receive fracture repair undergo simultaneousexploration of the adjacent rectus muscle(s) through sep-arate fornix incision(s), with minimal dissection. If anunrecognized flap is allowed to attach itself to or near theimplant material, the motility defect becomes more diffi-cult to treat later. If diplopia is due to flap tear, fracturerepair may not be necessary, but if entrapment and flaptear coexist, as in 3 cases of this series, combined repairproduces the best outcome.

ACKNOWLEDGEMENTS

The authors thank David S. Goldberg, MD; JohnAvallone, MD; David R. Stager Sr, MD; Robbin B.Sinatra, MD; Paula Gebhardt; Leonard Baham, COMT;and Maxine Haslauer for their assistance with this project.

REFERENCES

1. Wojno TH. The incidence of extraocular muscle and cranial nervepalsy in orbital floor blow-out fractures. Ophthalmology1987;94:682-687.

2. Metz HS, Scott WE, Madson E, et al. Saccadic velocity and activeforce studies in blow-out fractures of the orbit. Am J Ophthalmol1974;78:665-670.

3. von Noorden GK, Hansell R. Clinical characteristics and treatmentof isolated inferior rectus paralysis. Ophthalmology 1991;98:253-257.

4. Duke-Elder S, MacFaul PA. System of Ophthalmology. Vol 14. StLouis: CV Mosby; 1972;298-306.

5. Helveston EM. The relationship of extraocular muscle problemsto orbital floor fractures: Early and late management. Trans AmAcad Ophthalmol Otolaryngol 1977;83:660-662.

6. Emery JM, von Noorden GK, Schlernitzauer DA. Orbital floorfractures: Long-term follow-up of cases with and without surgicalrepair. Trans Am Acad Ophthalmol Otolaryngol 1971;75:802-812.

7. von Noorden GK. Binocular Vision and Ocular Motility. St Louis:CV Mosby; 1996;452-455.

8. Putterman AM. Management of orbital floor blowout fractures.Adv Ophthalmic Plast Reconstr Surg 1987;6:281-285.

9. Kushner BJ. Management of diplopia limited to down gaze. ArchOphthalmol 1995;113:1426-1430.

10. von Noorden GK. Binocular Vision and Ocular Motility. St Louis:Mosby; 1996;526-583.

11. Brown MS, Ky W, Lisman RD. Concomitant ocular injuries withorbital fractures. J Cranio-Maxillofac Trauma 1999;5(1):41-46.

12. Fradkin A. Orbital floor fractures and ocular complications. Am JOphthalmol 1977;699-700.

13. Holt JE, Hold R, Blodgett JM. Ocular injuries sustained duringblunt facial trauma. Ophthalmology 1983;90:14-18.

14. Cole HG, Smith B. Eye muscle imbalance complicating orbitalfloor fractures. Am J Ophthalmol 1963;55:930-935.

15. Demer JL, Oh SY, Poukens V. Evidence for active control of rectusextraocular muscle pulleys. Invest Ophthalmol Vis Sci2000;41:1280-1290.

16. Rumelt MB, Ernest JT. Isolated blowout fracture of the medialorbital wall with medial rectus muscle entrapment. Am JOphthalmol 1972;73:451-453.

17. Ruttum MS, Harris GJ. Orbital blowout fracture with ipsilateralfourth nerve palsy. Am J Ophthalmol 1985;100(2):343-344.

DISCUSSION

DR DAVID L. GUYTON. Dr Ludwig’s description of “flap”tears of the extraocular muscles is both fascinating andconvincing. Since the recent emphasis by Demer and col-leagues1 on the attachments between the orbital portionsof the extraocular muscles and the surrounding connec-tive tissue, strabismologists have been looking for practi-cal applications of this knowledge. Drs Ludwig andBrown’s flap tear mechanism appears to be consistentwith this new view of connective tissue attachments.

Even before the connective tissue “pulley” concept,though, the so-called check ligaments, encountered at thetime of surgery on the rectus muscles, have been wellknown to strabismus surgeons. Especially prominent arethe dense attachments to the inferior rectus muscle, rep-resenting the origin of the retractors of the lower lid.2,3

These particular attachments, also known as the capsu-lopalpebral head of the inferior rectus muscle, are verystrong indeed. It is therefore not surprising that orbitaltrauma from an assailant, or from the cotton-tipped appli-cator of a retinal detachment surgeon, could tear portionsof the inferior rectus muscle via these attachments, pro-ducing Dr Ludwig’s “flap” tear. Indeed 87% of theinvolved muscles in her series were inferior rectus mus-cles.

How were the several medial rectus and superior rec-tus muscles involved? Their check ligaments are not verystrong. Perhaps these cases were the result of locallydirected trauma, actually shearing off or avulsing a portionof the muscle. Such injuries have been documented peri-odically in the literature. In a case of mine several monthsago, the superior rectus muscle had been cleanly disin-serted from the globe purely by trauma.

Dr Ludwig’s contribution is more than just recogni-tion of this “flap” tear mechanism. She has successfullyrepaired most of her cases. Because she has used severalrepair techniques, though, we still do not know which ofthese are necessary. For example, how important is theclosing of rents in Tenon’s capsule? How important is thefree Tenon’s tissue graft that she has used over the surgi-cally repaired area? Should a non-reactive suture be usedinstead of an absorbable one? How important are rangeof movement exercises postoperatively, and do the



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patients really do them? I am confident that Dr Ludwig will continue to

research these questions. I congratulate her and her co-author Mark Brown for an engaging and provocative pres-entation.

REFERENCES

1. Demer JL, Oh SY, Poukens V. Evidence for active control of rectusextraocular muscle pulleys. Invest Ophthalmol Vis Sci2000;41:1280-1290.

2. Hawes MJ, Dortzbach RK. The microscopic anatomy of the lowereyelid retractors. Arch Ophthalmol 1982;100:1313-1318.

3. Pacheco EM, Guyton DL, Repka MX. Changes in eyelid positionaccompanying vertical rectus muscle surgery and prevention oflower lid retraction with adjustable surgery. J Pediatr OphthalmolStrabismus 1992;29:265-272.

[Editor’s notes] DR EDWARD L. RABB asked why it wasnecessary to advance the torn flap. DR MALCOLM R. INGasked if an abrupt difference in muscle thickness suggest-ing a flap tear could be identified on a CT scan prior tosurgical exploration.

DR IRENE H. LUDWIG. Regarding Dr Guyton’s questions,I am not sure how important all these repairs are. Myinstinct is to fix a defect when I see it. I don’t know if clos-ing Tenon’s capsule or employing a Tenon’s graft is neces-sary. I did have 2 cases redetach when I didn’t use themethod of repair I described earlier. I had usedabsorbable sutures to reattach the flap, and I had not fullyrestored Tenon’s capsule. Both of these cases were in chil-dren, who also did not exercise their motility postopera-tively. I then repeated the surgeries the same as the ini-tial repairs, but used non-absorbable sutures for flap reat-tachment, and free Tenon’s graft over the muscles afterrepair. Their mothers increased the eye movement exer-cises. The second procedures worked.

Dr Guyton’s suggestion of using a non-reactive sutureto repair Tenon’s capsule is an excellent idea. Perhaps a7-0 polypropylene would serve well for this.

The patient’s parents and/or spouses were chargedwith the importance of beginning the range of movementexercises immediately upon awakening. Several of thosewho admitted to poor compliance did not do well, but I donot have enough data to analyze this point. It is easyenough to recommend eye movement exercises, and itmay be important.

To answer the question about imaging studies to pre-operatively demonstrate a flap tear, I obtained no usefulinformation from any of the preoperative CT and MRIscans I obtained. All were read as normal with respect tothe extraocular muscles, excepting several with orbitalfractures and posterior muscle entrapment. No anteriorabnormality could be specifically identified. A fewshowed vague scar tissue or edema under the inferior rec-tus, but these had already undergone orbital fracturerepair. One case (case 2 in the manuscript), had severalrepeat high resolution MRI scans performed of the sus-pect inferior rectus, with no abnormality seen by the radi-ologist, despite my insistance that something must bethere. I talked myself into thinking the muscle capsulewas irregular, but there was really no useful informationobtained. His flap was small. The MRI scan would havedeterred most from exploring the muscle. I now limitimaging to orbital CT scans to look for fractures.

To answer the question about why I advance the flapto the insertion, when some flaps originate a few millime-ters posterior to the insertion, I do this when there is atether limiting the action of the muscle. This tends tostrengthen the muscle. In those muscles with restrictionof gaze away from the muscle action, I leave the flap a lit-tle further back.


Documents

STRABISMUS DUE TO FLAP TEAR OF A RECTUS MUSCLE* · 2016. 7. 19. · Tr. Am. Ophth. Soc. Vol. 99, 2001 53 STRABISMUS DUE TO FLAP TEAR OF A RECTUS MUSCLE* BY Irene H. Ludwig, MDAND