Brown Syndrome
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Disease Entity
Strabismus/ocular misalignment
Disease
Brown syndrome is a form of vertical strabismus characterized by limited elevation of the eye in an adducted position, secondary to abnormalities in the superior oblique tendon-trochlea complex.[1][2][3][4]
The condition may be congenital or acquired, is bilateral in approximately 10% of cases, and has a slight female predominance.[5] [2] Although a genetic predisposition has been proposed in congenital cases,[6] most are sporadic in nature.
Pathophysiology and Etiology
The exact mechanisms underlying Brown syndrome remain a topic of ongoing investigation.
First described in 1950 by Dr. Harold Whaley Brown as “superior oblique tendon-sheath syndrome,” the condition was initially attributed to dysgenesis of the superior oblique tendon sheath.[1] [7] Brown noted that many patients exhibited a tight or shortened tendon, mechanically restricting the superior oblique muscle and limiting upward and inward eye movement.
Current evidence suggests that dysfunction of the superior oblique tendon-trochlear complex may be the primary mechanism. The superior oblique tendon, its fibrocartilaginous trochlea, and associated sheath structures work together to allow smooth ocular movement, particularly elevation in adduction. Structural anomalies such as a short or inelastic tendon, trochlear malformation, nodules on the tendon, fibrosis, or inflammatory changes within this complex can result in the characteristic motility limitation [3][8][9]
Some cases of Brown syndrome have been associated with congenital cranial dysinnervation disorders (CCDDs), implicating aberrant innervation of the extraocular muscles. Maldevelopment of the fourth cranial nerve and its axons can result in incomplete formation of the superior oblique tendon–muscle–trochlea complex, producing the clinical features observed in some patients.[10] However this mechanism does not fully explain all presentations.[11]
More recent surgical observations have identified fibrotic strands connecting the posterior superior oblique tendon to the trochlea. These strands, which share the tendon’s insertion site, may explain both classic and atypical presentations of Brown syndrome, including variable elevation deficits.[11]
Congenital versus Acquired Brown Syndrome
Brown syndrome can be classified as either congenital or acquired:
Congenital: Present at birth, typically painless, and unrelated to infection or inflammation.
Acquired: Develops after infancy and may be intermittent. Symptoms can include pain or a clicking sensation during superonasal eye movement. Acquired cases may result from trauma, scarring near the trochlea, tendon cysts, orbital masses, inflammatory or infectious processes (e.g., sinusitis), reduced tendon elasticity (after thyroid eye disease or peribulbar anesthesia), or iatrogenic causes following procedures such as scleral buckle placement, strabismus repair, or sinus surgery. Systemic inflammatory diseases, including juvenile idiopathic arthritis, rheumatoid arthritis, and systemic lupus erythematosus, can also cause secondary Brown syndrome through peritrochlear inflammation and scarring.[3][8]
Diagnosis
The diagnosis of Brown syndrome is based on the clinical findings and history. Further workup may be needed in acquired Brown syndrome and often depends on the suspected underlying etiology. For example, workup for a suspected inflammatory etiology may require laboratory testing for autoimmune or systemic disease, while suspected trauma may prompt additional imaging. Orbit and sinus imaging is advisable in acute onset cases of unknown etiology.
Physical Examination
A complete ophthalmic examination is required with emphasis on strabismus measurements in all cardinal positions, ocular motility and binocular function. In acquired cases a thorough orbital examination should be performed with special attention to the trochlear area.
Signs
The key finding in Brown syndrome is limited or no elevation in adduction. Limited elevation in straight-up gaze and abduction can also be present, but are more subtle. Other features that may be present include V pattern deviation in up gaze, eyelid widening in adduction, the presence of hypotropia in the primary position, and down shoot in adduction.[3]
- Mild: there is no vertical deviation in primary position or downshoot in adduction.
- Moderate: there is no vertical deviation in primary position, but there may be a downshoot in adduction.
- Severe: there may be both a hypotropia in primary position and downshoot in adduction.[12]
A compensatory abnormal head position may also be present in some cases; patients may adopt a chin up position or a head turn away from the affected eye (to keep the affected eye abducted, avoid hypotropia, and promote binocular fusion).
In some cases, the down movement of the eye on adduction may mimic superior oblique overaction with or without associated IO palsy. However, in Brown syndrome attempts at straight upwards elevation may cause a V pattern (divergence on up-gaze), due to lateral slippage of the globe due to resistance from a tight superior oblique tendon. In contrast an A-pattern (divergence on down-gaze) is most likely to be seen in superior oblique over-action with or without associated IO palsy.[5] Saccadic eye movements should remain unaffected in contrast to Superior Oblique Myokymia (SOM).
Forced duction testing is very useful in the diagnosis of Brown syndrome, and will demonstrate restriction to passive elevation in adduction, accentuated by retropulsion of the globe (which stretches the superior oblique tendon).
A tendon cyst or a mass may be palpable in the superonasal orbital area in rare cases. Brown Syndrome secondary to an inflammatory condition is frequently associated with orbital pain and tenderness on movement or palpation of the trochlea.
Symptoms
Patients with Brown syndrome may have a variety of symptoms which may be constant, intermittent, or recurring, including:
- Vertical diplopia
- Reduced binocular vision/stereopsis
- Orbital pain and tenderness
- Pain with eye movement
- Abnormal head position
- An audible or palpable “click” on attempted elevation in adduction
Differential diagnosis
Brown syndrome should be differentiated from the following conditions:
- Inferior oblique muscle palsy
- Superior oblique over-action
- Double elevator palsy
- Congenital fibrosis of extraocular muscle
- Thyroid eye disease
- Orbital fracture with entrapment
- Myasthenia gravis
Management
Management of Brown syndrome depends on symptomatology, etiology, and the course of the disease.
Observation
Asymptomatic or mild congenital cases are usually managed conservatively, as spontaneous improvement over time (sometimes after many years) has been described in up to 75-80% of cases.[13] [14] Of note, as patients are most symptomatic on upgaze, normal growth can decrease symptoms as patients grow taller and require less up gaze. Some cases of acquired Brown syndrome may also undergo spontaneous resolution, and thus early surgical intervention is not recommended.[15][2]
Medical Therapy
- Systemic therapy: Corticosteroids, NSAIDs, and immunosuppressants may be indicated for acquired cases, depending on the underlying etiology. When Brown syndrome is associated with autoimmune disease, it may follow a relapsing–remitting course that mirrors systemic disease activity. In some instances, the motility limitation can improve or resolve as the underlying condition is brought under control with systemic treatment.
- Peritrochlear steroid injections have been used in cases of trochleitis.[16] Some patients may require recurrent treatments for symptomatic relief.
- Biologics: Anti-TNF agents (adalimumab, infliximab) and JAK inhibitors have shown success in refractory inflammatory cases.
Surgery
Surgery is indicated in the following circumstances:
- Hypotropia in primary position
- Significant abnormal head position
- Significant diplopia
- Significant downshoot on adduction
- Compromised binocularity
- Significant orbital pain or pain with eye movements
Surgical techniques
- Superior oblique tendon elongation: have been found to have high success rates minimizing the risk of postoperative palsy. Procedure can be performed through a variety of techniques, including a silicon expander (e.g. a #240 retinal silicone band)[17], a non-absorbable "Chicken suture", or a superior oblique split tendon elongation procedure.[18][19]
- Superior oblique tenotomy or tenectomy: because this procedure usually causes a post-operative iatrogenic superior oblique palsy, it is often combined[20]
- Superior oblique tendon thinning[21]
- Trochleoplasty or cyst excision: Considered in mass or scar-related cases.
- Reversal of muscle plication: required in iatrogenic Brown syndrome secondary to muscle plication
References
- ↑ 1.0 1.1 Brown HW. Congenital structural muscle anomalies. In Allen JH (ed.) Symposium on strabismus. Trans New Orleans Acad Ophthalmol. St. Louis, MO: Mosby Year-Book, 1950, pp. 205–236.
- ↑ 2.0 2.1 2.2 Wright KW. Brown’s syndrome: diagnosis and management. Trans Am Ophthalmol Soc 1999; 97: 1023–1109.
- ↑ 3.0 3.1 3.2 3.3 Khorrami-Nejad M, Azizi E, Tarik FF, Akbari MR. Brown syndrome: a literature review. Ther Adv Ophthalmol. 2024;16:25158414231222118. Published 2024 Feb 22.
- ↑ Parks MM, Brown M. Superior oblique tendon sheath syndrome of Brown. Am J Ophthalmol 1975; 79: 82–86.
- ↑ 5.0 5.1 American Academy of Ophthalmology. Pediatric Ophthalmology and Strabismus BCSC, 2024-2025
- ↑ Magli A, Fusco R, Chiosi E, et al. Inheritance of Brown’s syndrome. Ophthalmologica 1986; 192: 82–87.
- ↑ Parks MM, Brown M. Superior oblique tendon sheath syndrome of Brown. Am J Ophthalmol 1975; 79: 82–86.
- ↑ 8.0 8.1 Wright KW. Pediatric Ophthalmology and Strabismus. 4th ed. Springer; 2021
- ↑ von Noorden GK, Campos EC. Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 7th ed. Elsevier; 2018
- ↑ Coussens T, Ellis FJ. Considerations on the etiology of congenital Brown syndrome. Curr Opin Ophthalmol 2015; 26: 357–361.
- ↑ 11.0 11.1 Muehlendyck H, Ehrt O. Brown’s atavistic superior oblique syndrome: etiology of different types of motility disorders in congenital Brown’s syndrome. Ophthalmologe 2020; 117: 1–18.
- ↑ Fu L, Malik J. Brown syndrome. StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing, 2022.
- ↑ Dawson E, Barry J, Lee J. Spontaneous resolution in patients with congenital Brown syndrome. J AAPOS 2009; 13: 116–118.
- ↑ Kaban TJ, Smith K, Orton RB, et al. Natural history of presumed congenital Brown syndrome. Arch Ophthalmol 1993; 111: 943–946.
- ↑ Gregersen E, Rindziunski E. Brown’s syndrome: a longitudinal long-term study of spontaneous course. Acta Ophthalmol 1993; 71: 371–376.
- ↑ Giannaccare G, Primavera L, Maiolo C, et al. Steroid intra-trochlear injection for the treatment of acquired Brown syndrome secondary to trochleitis. Graefes Arch Clin Exp 2017; 255: 2045–2050.
- ↑ Wright KW. Superior oblique silicone expander for Brown syndrome and superior oblique overaction. Thorofare, NJ: SLACK Incorporated, 1991, pp. 101–107.
- ↑ Dubinsky-Pertzov B, Pras E, Morad Y. Superior oblique split tendon elongation for Brown's syndrome: Long-term outcomes. Eur J Ophthalmol. 2021;31(6):3332-3336. doi:10.1177/1120672121991050
- ↑ Moghadam AAS, Sharifi M, Heydari S. The results of Brown syndrome surgery with superior oblique split tendon lengthening. Strabismus 2014; 22: 7–12.
- ↑ Sprunger DT, von Noorden GK, Helveston EM. Surgical results in Brown syndrome. Thorofare, NJ: SLACK Incorporated, 1991, pp. 164–167
- ↑ Galán A, Roselló N. Superior oblique tendon thinning for Brown syndrome. J AAPOS 2021; 25: 35–35.
