Journal of Neuro-Ophthalmology, June 1988, Volume 8, Issue 2

Acquired Brown's Syndrome in a Patient with an Orbital Roof Fracture

A 31-year-old white man was found to have Brown's syndrome following severe closed-head injuries sustained in a motorcycle accident. Computed tomography scans revealed a displaced fracture of the right orbital roof, with entrapment of the superior oblique muscle. Surgical attempts to free the muscle were unsuccessful, so the superior oblique tendon was recessed 10 mm, and the inferior rectus was recessed on an adjustable suture. We believe this to be the first report of a case of entrapment producing an acquired Brown's syndrome and the first case of a motility disorder resulting from entrapment of an extraocular muscle in an orbital roof fracture.

10umal of Clinirnl Neuro-ophlhalmology 8(2): 127-130,1988. Acquired Brown's Syndrome in a Patient with an Orbital Roof Fracture Larry Baldwin, M,D" and Robert S. Baker, M.D. <9 1988 Raven Press, Ltd., New York A 31-year-old white man was found to have Brown's syndrome following severe closed-head injuries sus­tained in a motorcycle accident. Computed tomography scans revealed a displaced fracture of the right orbital roof, with entrapment of the superior oblique muscle. Surgical attempts to free the muscle were unsuccessful, so the superior oblique tendon was recessed 10 mm, and the inferior rectus was recessed on an adjustable suture. We believe this to be the first report of a case of entrapment producing an acquired Brown's syndrome and the first case of a motility disorder resulting from entrapment of an extraocular muscle in an orbital roof fracture. Key Words: Acquired Brown's syndrome-Orbital roof fracture. From the Departments of Ophthalmology, Neurology, Neu­rosurgery, and Pediatrics, University of Kentucky, Lexington, Kentucky, U.S.A. Address correspondence and reprint requests to Dr. L. BaldWin, Department of Ophthalmology, University of Ken­tucky, Lexington, KY 40536-0084, U.S.A. 127 Orbital fractures as a result of facial trauma may be associated with a spectrum of serious complica­tions. Common sequellae include intracranial in­jury, ocular and optic nerve damage, orbital struc­tural deformities, and motility disturbances. Al­though entrapment is often the source of extraocular muscle imbalance in blowout fractures of the inferior and medial orbit, the abnormalities seen with roof fractures are usually produced by bony fragments protruding into the orbit and im­pinging on the superior rectus (1). Roof fractures may also be associated with cranial nerve palsies secondary to injury of the superior orbital fissure and dysfunction of the superior oblique as the re­sult of trochlear displacement (2). In the absence of a roof fracture, superior oblique weakness is most often caused by a re­mote injury of the trochlear nerve producing a su­perior oblique palsy, although direct injury to the muscle or tendon may produce a similar picture. An uncommon, but distinctive, motility abnor­mality seen with trauma to the superior medial orbit is acquired Brown's syndrome. In the five re­ported cases, hemorrhage and inflammation of the tendon sheath and peritrochlear tissue have been implicated in limiting excursion of the superior oblique tendon (3-6). Here we describe a case of acquired Brown's syndrome resulting from entrapment of the supe­rior oblique muscle in an orbital roof fracture, We believe that this is the first case of entrapment pro­ducing an acquired Brown's syndrome and the first case of a motility disorder resulting from en­trapment of an extraocular muscle in an orbital roof fracture. CASE REPORT A 31-year-old white man sustained severe closed head injuries during a motorcycle accident 128 L. BALDWIN AND R. S. BAKER in May 1986. Computed tomography scans on ad­mission revealed right superior orbital rim and basilar skull fractures. Poor elevation of the right eye was noted during the initial hospitalization and was thought to be the result of marked perior­bital swelling. Visual complaints persisted after discharge, and the patient was found to have a V-pattern exo­tropia, an inability to elevate the right eye in an adducted position, and a 12 diopter right hypo­tropia in primary gaze (Fig. 1). Forced duction testing was positive for restriction of upgaze in the adducted position. No limitation of depression of the right eye in adduction was found, and no re­striction of elevation of the right eye in abduction was noted. Axial and coronal computed tomog­raphy scans of the orbits showed a displaced me­dial orbital roof fracture with entrapment of the superior oblique muscle (Fig. 2). At surgery, attempts to free the muscle were unsuccessful, and the superior oblique tendon was recessed 10 mm as an alternative procedure. In addition, the inferior rectus muscle was re­cessed on an adjustable suture. There was a small right hypertropia in the immediate postoperative period that was neutralized with adjustment of the inferior rectus suture. Six weeks postopera­tively, the patient had no vertical diplopia, a small exophoria, and two diopters of right hypertropia in primary gaze. A 2 prism diopter Fresnel prism was placed in the patient's glasses with the base at 30 degrees. Follow-up visit at 14 weeks postopera­tively revealed an 8 prism diopter right hyper­tropia in primary gaze that increased in adduction. The patient was then lost to follow-up. DISCUSSION Brown's superior oblique tendon sheath syn­drome was first described as a congenital entity involving limited movement of the superior oblique tendon (7). The clinical findings of limited upgaze in adduction on both passive and volun­tary rotation can also be acquired in patients with adult and juvenile rheumatoid arthritis (8-13), si­nusitis (14,15), and following sinus surgery (15-17) or orbital trauma (3-6). In the five pre­viously reported cases of traumatically acquired Brown's syndrome, all have cited blunt trauma to the medial orbit as the precipitating event. Al­though a definitive mechanism was elucidated in only one case (cystic hematoma of the superior oblique tendon) (6), tendon sheath hemorrhage or orbital soft tissue inflammation has been postu­lated as the cause in each case. Other authors have suggested that posttraumatic scarring may be responsible for the findings, but definitive case re­ports are not available. V-pattern exotropia is a common finding in true and acquired Brown's syndrome, but there has been little discussion about the mechanism in­volved. As the eye looks upward and the insertion of the superior oblique rotates downward, the fixed distance between the insertion and trochlea in Brown's syndrome creates a tethering effect that mechanically produces an exotropia and incy­clotropia. Our patient demonstrated the character­istic V-pattern exotropia; torsion in upgaze was not measured. Superior orbital fractures are an infrequent re­sult of head trauma; Schultz estimated Q.ll Lnci- FIG. I. Ocufar v,ers,lons snowing decreased elevation of the right eye in adduction, normal elevation in abduction cmd cr,:>ract2nSliC ·J-pattern 8x n lropla (see text). ' ACQUIRED BROWN'S SYNDROME 129 FIG. 2. Coronal computed to­mography scan of the orbits il­lustrating a right orbital roof fracture with entrapment of the superior oblique muscle (large arrow). Note also a fracture overlying the superior rectus (small arrow). dence of only 5% in cases involving fractures of other facial bones (18). Although diplopia is quite common in depressed roof fractures, this is almost invariably the result of bony fragments com­pressing and restricting the extraocular muscles (19). The superior rectus is commonly compro­mised with decreased elevation in all positions of gaze. The superior oblique may be indirectly af­fected, either by displacement of the trochlear ap­paratus or by damage to the trochlear nerve as it traverses the orbit. Although entrapment of orbital fat within fracture sites has been found (20), no previous account of extraocular muscle entrap­ment within a roof fracture cleft has been re­ported. Recognition of the characteristic motility defect and forced ductions testing will help to differen­tiate traumatically acquired Brown's syndrome from other motility disorders resulting from orbital injury. Although entrapment of the inferior rectus in a blowout fracture and restriction of the supe­rior rectus by bone chips may mechanically limit upgaze with positive forced ductions, this abnor­mality is seen in both abduction and adduction. Knapp's type VII superior oblique palsy contains an element of mild Brown's syndrome, but the palsy is the predominant finding (21,22). Trau­matic inferior oblique palsy may be confused with Brown's syndrome because of an inability to ele­vate the eye in adduction, but forced duction testing will be negative. The goal of surgical correction should be the re­lease of the entrapped muscle from the fracture site, but excessive scar formation in our patient necessitated the alternative procedures of superior oblique and inferior rectus recessions. This tech­nique has been successful in other cases of trau­matic Brown's (6), but in this patient, superior oblique weakness was produced. In conclusion, extraocular muscle entrapment, particularly the superior oblique, should be con­sidered in the setting of motility abnormalities re­sulting from an orbital roof fracture. It can be dis­tinguished from other causes of diplopia by careful observation of limited elevation in adduc­tion and positive forced ductions. Surgical correc­tion, either by the release of the entrapment or by superior oblique weakening procedure, may be ef­fective, but superior oblique weakness may be produced. , eli" NCliro-ophtitall1lol. Vol. 8. No.2, 1988 130 L. BALDWIN AND R. S. BAKER REFERENCES 1. McLachlan DL, Flanagan Je Shannon GM. Complications of orbital roof fractures. Ophthalmology 1982;89:1274. 2. Converse JM, Smith B, Wood-Smith D. Orbital and naso­orbital fractures. In: Converse JM (ed), Reconstructil'e Plastic Surgery, 2nd ed. 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