Brown syndrome, in simplest terms, is characterized by restriction of the superior oblique trochlea-tendon complex[1] such that the affected eye does not elevate in adduction. Individuals with Brown syndrome may exhibit compensatory head turn or chin-up head posture and, occasionally, amblyopia.[2] The condition is usually unilateral but can be bilateral.
Congenital Brown syndrome is more common than acquired Brown syndrome. Congenital Brown syndrome can be associated with and possibly in the spectrum of congenital cranial dysinnervation disorders. Acquired causes of Brown syndrome include inflammation and trauma.
In 1950, Harold W. Brown first published on an unusual motility disorder, characterized by the following: limited elevation in adduction; divergence in straight upgaze (V-pattern); same degree of limitation on versions, ductions, and forced ductions; widening of the palpebral fissure on adduction; normal or near normal elevation in abduction; restricted forced ductions to elevation in adduction; and compensatory chin elevation for binocular fusion.
Brown attributed the limited elevation to a short or tight anterior superior oblique tendon sheath. He termed this as superior oblique tendon sheath syndrome. The syndrome could be acquired or intermittent. In some cases, spontaneous resolution may occur. He further hypothesized that the short tendon sheath was due to a complete congenital paresis of the ipsilateral inferior oblique muscle and secondary to sheath contracture.
In the early 1970s, Brown redefined the sheath syndrome with the following divisions: true sheath syndrome characterized only those cases that have a congenital short anterior sheath of the superior oblique tendon, and simulated sheath syndrome characterized all cases with the clinical features of a sheath syndrome caused by an anomaly other than a congenital short anterior sheath of the superior oblique tendon.[3] Clinical features of true and simulated sheath syndromes were similar, but true sheath syndrome was always congenital and constant without spontaneous recovery.
In the mid-1970s, Parks and colleagues reported that a tight tendon sheath was not the cause of Brown syndrome; instead, it was a tight or short superior oblique tendon.[4] Subsequent studies confirmed the cause of the syndrome to be a tight or inelastic superior oblique tendon.
Brown syndrome can be differentiated into congenital and acquired, with congenital causes being more common. Congenital cases may represent a congenital cranial dysinnervation disorder.[5] With the exception of entities such as congenital cranial dysinnervation disorders, Brown "syndrome" may be a misnomer, if the problem is isolated to the eye. Notwithstanding as the term Brown "syndrome" is so entrenched, this article will not alter the terminology.
Congenital Brown syndrome
Superior oblique Brown syndrome
Superior oblique Brown syndrome or true Brown syndrome is restriction of eye movement up and adduction caused by an abnormal superior oblique muscle or tendon. As originally demonstrated by Brown, normal elevation of the eye into adduction increases the distance between the trochlea and the superior oblique insertion as the eye moves up and into adduction. A tight or inelastic superior oblique tendon muscle complex would restrict ocular elevation in adduction. Many theories for the cause of the tight or inelastic tendon exist.
Etiology of superior oblique Brown syndrome
Helveston theory of abnormal telescoping mechanism
Until recently, it was believed that the superior oblique tendon moves through the trochlea much like a rope through a pulley. Through a detailed anatomical study, Helveston showed that the tendon-slackening distal to the trochlea comes from a telescoping elongation of the central tendon.[6]
Telescoping elongation of the tendon is due to movement of the central tendon fibers, which have scant interfiber connections.
Congenital Brown syndrome could be caused by a developmental abnormality of the elastic-crossed fibers that normally allow the telescoping movement of the central tendon fibers.
Wright hypothesis of congenital inelastic superior oblique muscle-tendon complex
In 1999, Wright described a computer simulation of Brown syndrome, using two specific models, as follows: (1) a short superior oblique tendon, and (2) a stiff superior oblique tendon (stretched sensitivity). The computer model showed that a tight or inelastic muscle-tendon complex was the best fit for the Brown syndrome pattern of deviation.
The best simulation of Brown syndrome was obtained with 250% stretched sensitivity, producing a -4 limitation of elevation in adduction and a -1 limitation of elevation in abduction. With this simulation of a stiff superior oblique muscle-tendon complex, there was a very small deviation in primary position and no deviation in downgaze, which is consistent with the clinical findings of Brown syndrome.
Shortening the tendon from 32 mm to 28 mm did not significantly limit the elevation in adduction; however, shortening the tendon to 22 mm created a -4 limitation of elevation in adduction. Shortening the tendon to 22 mm also caused a hypotropia of 11 prism diopters (PD) in primary position and a hypotropia of 7 PD in downgaze, which is inconsistent with the classic clinical findings of Brown syndrome, where the deviation in primary position is very small to nonexistent and there is no hypotropia in downgaze.
Thus, the best computer model for Brown syndrome is a stiff or inelastic muscle-tendon complex. Perhaps, congenital Brown syndrome is a form of congenital fibrosis of the superior oblique muscle, which results in a stiff or inelastic muscle-tendon complex.[7]
Nonsuperior oblique Brown syndrome
Nonsuperior oblique Brown syndrome or pseudo-Brown syndrome is a restriction of ocular elevation in adduction caused by pathology other than an abnormality of the superior oblique muscle or tendon.
Etiology of congenital nonsuperior oblique Brown syndrome
Congenital bands: Inferior orbital fibrous adhesions or fibrous bands to the posterior globe are rare causes of restriction of elevation in adduction.
Congenital inferior location of lateral rectus muscle pulley: Rare case of congenital Brown syndrome are caused by congenital inferior location of the lateral rectus muscle. In these cases, the limitation of elevation in adduction is caused by the stiff lateral rectus muscle that is congenitally located inferior to the normal position.[8]
Acquired Brown syndrome
Acquired superior oblique Brown syndrome
See Causes.
Etiology of acquired superior oblique Brown Syndrome
Abnormal telescoping mechanism
In constant or intermittent acquired Brown syndrome, reduced telescoping elongation of the superior oblique tendon would be due to one of the following: vascular dilatation of the tendon sheath vessels and local edema occurring within the confined area of the trochlea.
Tight or inelastic superior oblique tendon
A tight superior oblique tendon can be caused by a mass that displaces the tendon, a scleral buckling, or a superior oblique tendon tuck.
A rare acquired fibrosis of the superior oblique muscle is possibly associated with thyroid disease, an intramuscular injection of local anesthetic, or Hurler-Scheie syndrome.
Acquired short tendon
This condition could be caused by a superior oblique tendon tuck, a mass that displaces the tendon, or a scleral buckling.
Superior oblique click syndrome
This theory has been used to explain acquired Brown syndrome that is associated with inflammatory conditions.
Inflammation produces a nodule on the superior oblique tendon, just posterior to the trochlea. The nodule would have difficulty entering the trochlea, thus restricting tendon movement.
Chronic movement of the superior oblique tendon through the trochlea can result in a traumatic tenosynovitis with tendon-swelling and stenosis of the surrounding tendon sheath.
Trigger-thumb is a congenital or acquired constriction or stenosis of the fibrous sheath, which surrounds the tendon and causes secondary enlargement of the tendon proximal to the constriction.
The combination of a sheath-stenosis and tendon swelling prevents movements of the tendon.
Peritrochlear scarring
Scarring or fibrosis around the trochlea and the anterior superior oblique tendon would restrict the tendon movement, causing Brown syndrome.
Extensive scarring around the trochlea can result in restriction of the tendon movement in both ways, resulting in both a Brown syndrome and a superior oblique palsy (canine tooth syndrome). This can be caused by trauma, periocular surgery, and upper lid blepharoplasty with removal of periorbital fat with cautery.
Acquired nonsuperior oblique Brown syndrome
Etiology of acquired nonsuperior oblique Brown syndrome
Acquired nonsuperior oblique etiologies: Inferior orbital fibrous adhesions to the posterior globe are caused by the following: orbital floor fracture and fat adherence syndrome associated with inferior orbital trauma.
Superior nasal orbital mass: These patients usually demonstrate a large vertical deviation in primary position often associated with exotropia. Possible causes are a glaucoma drainage implant or a neoplasm in the superior orbital quadrant.
Scarring in the inferior temporal anterior orbit to the globe will cause a pattern of restriction that looks very similar to Brown syndrome with restriction of elevation in adduction. Unlike superior oblique Brown syndrome, there is also restriction to adduction. The author had seen this with scarring and fat adherence after transconjunctival blepharoplasty.
Orbital floor fracture can rarely cause a restriction of elevation that looks like Brown syndrome. In these cases, a similar elevation defect in adduction and abduction is present.
Frequency of this condition is 1 in 400-450 strabismus cases.
Although familial Brown syndrome appears to be rare, Wright showed that 35% of patients with congenital Brown syndrome had a family member with amblyopia or strabismus.[7] This finding might indicate the presence of an underlying genetic trait.
International
Same as in the United States.
Mortality/Morbidity
Amblyopia, strabismus, and an abnormal head position may be findings from Brown syndrome.
Race
No racial predilection exists.
Sex
In Brown's classic study of 126 patients, he reported that there was a higher incidence of the syndrome in females (59%) than in males (41%). A right-eye bias also occurred; involvement was 55% in right eyes, 35% in left eyes, and 10% bilateral.
Wright found 5% of bilateral cases and analyzed the male-female distribution of Brown syndrome according to different subgroups: congenital Brown syndrome (almost identical sex distribution), idiopathic acquired Brown syndrome (63% females), and traumatic acquired Brown syndrome (82% males).[7]
Diplopia may occur when the patient looks up and to the contralateral side of the affected eye. Patients with congenital Brown syndrome rarely complain of diplopia, because most patients have developed suppression. Patients with acquired Brown syndrome in late childhood or adulthood experience diplopia when tropic.
Pain is a feature.
Some patients with acquired Brown syndrome present with inflammatory signs.
These signs include supranasal orbital pain, tenderness, intermittent limitation of elevation in adduction, and pain that is associated with this ocular movement.
Characteristic physical findings of Brown syndrome are discussed below.
Limited elevation in adduction, an invariable sign, is the hallmark of Brown syndrome. The amount of limited elevation in adduction can range from minimal (-1) to severe (-4). The severe form has been termed Brown plus. Even in severe cases of congenital Brown syndrome, there is minimal hypotropia in primary position and no hypotropia in downgaze.
A significant limitation of elevation in abduction is present in 70% of patients, but it is the difference between elevation in adduction versus elevation in abduction that differentiates Brown syndrome from such disorders as double elevator palsy (where elevation is equal to or worse in abduction).
A lack of significant hypotropia in primary position in cases of nontraumatic Brown syndrome has been observed. In contrast, much larger hypotropias have been observed in cases of Brown syndrome associated with trauma or periorbital surgery.
If the vertical deviation in primary position is greater than 10-12 PD, consider an inferior oblique palsy, severe periocular scarring, or a superior nasal mass; do not consider Brown syndrome caused by a tight or inelastic superior oblique tendon.
Patients often present with compensatory head-posturing, their chin up, and a contralateral face turn to avoid the hypotropia that increases in upgaze and gaze to the contralateral side of the affected eye.
In one series, amblyopia was found in 16% of patients with Brown syndrome.[2] However, amblyopia is unusual in most patients with good binocular fusion.
Minimal or no superior oblique overaction and positive forced ductions up and in are present. The presence of even mild superior oblique overaction should be regarded with suspicion, since this finding is inconsistent with Brown syndrome of superior oblique tendon etiology.
A feature that often is associated with acquired Brown syndrome is an audible or palpable superior nasal click on ocular rotations up and nasalward; sometimes, the pain is associated with this ocular movement.
Digital pressure in the area of the trochlea can unlock and improve ocular rotations in some cases.
Contralateral pseudoinferior oblique overaction occurs because of the limited elevation in abduction. Because of the Hering law of yoke muscles, increased innervation to the contralateral inferior oblique muscle occurs as the eye with Brown syndrome tries to elevate and abduct. Apparent inferior oblique overaction disappears when the superior oblique restriction is relieved.
The positive forced ductions maneuver is a critical part of the syndrome; it equals the limitation that is seen on ductions and versions.
A positive forced ductions test, by itself, does not indicate a tight superior oblique muscle tendon as the cause of Brown syndrome. Nonsuperior oblique restrictions (eg, inferior orbital adhesions) can restrict ocular elevation in adduction.
Objective fundus torsion: In Brown syndrome secondary to a tight superior oblique tendon, intorsion occurs as the eye moves up and encounters the tight superior oblique tendon. Clinically, no torsion occurs in primary position or downgaze, but intorsion in upgaze does occur. Fundus torsion is shown in the images below.
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Fundus torsion (direct view). The bottom set of fundus photographs represents downgaze; the center photographs, primary position; and the top photogra....
The images below show acquired Brown syndrome.
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A 3-year-old patient with acquired right Brown syndrome. Marked limitation of elevation in adduction is present in the right eye. Pseudo-overaction of....
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The same patient as in the image above, 6 years later. The patient shows normal eye movements, and no signs of Brown syndrome. A spontaneous resolutio....
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Composite photographs, showing left Brown syndrome with marked limitation of elevation in adduction. Courtesy of Kenneth Wright, MD.
Peritrochlear scarring and adhesions - Chronic sinusitis, trauma (superior temporal orbit), blepharoplasty and fat removal, and lichen sclerosus et atrophicus and morphea
Tendon-trochlear inflammation and edema - Idiopathic inflammatory (pain and click), trochleitis with superior oblique myositis, acute sinusitis, adult rheumatoid arthritis, juvenile rheumatoid arthritis, systemic lupus erythematosus, possibly distant trauma (cardiopulmonary resuscitation [CPR] and long bone fractures), and possibly postpartum hormonal changes
Superior nasal orbital mass - Glaucoma implant and neoplasm
Tight or inelastic superior oblique muscle - Thyroid disease (inelastic muscle), peribulbar anesthesia (inelastic tendon), Hurler-Scheie syndrome (inelastic tendon), and superior oblique tuck (short tendon)
No laboratory tests are specifically required in the workup of congenital Brown syndrome.
In cases of acquired, nontraumatic Brown syndrome, tests to exclude autoimmune diseases, such as lupus, juvenile rheumatoid arthritis (JRA), and rheumatoid arthritis, may need to be ordered.
Consider MRI of the orbit for acquired Brown syndrome, especially if associated with pain, discomfort, signs of inflammation, or an atypical pattern of strabismus.
In some cases, imaging studies may identify pathology in the area of the trochlea, even superior nasal orbital tumors and sinusitis.
Spontaneous resolution of Brown syndrome rarely occurs; if it does, it is more likely in nontraumatic acquired cases. Because of the possibility for late spontaneous recovery, a conservative approach to management is justified, especially for patients with nontraumatic acquired cases.
Acquired Brown syndrome
Patients with acquired Brown syndrome should be evaluated medically for coexisting systemic disease.
If a disorder, such as rheumatoid arthritis or sinusitis, is identified, treat accordingly.
Once systemic disease is excluded, patients who have acquired Brown syndrome with signs of inflammation can be treated with anti-inflammatory medication. Oral ibuprofen is a good first-line choice. Local steroid injections in the area of the trochlea and oral corticosteroids can be used for inflammation.[9]
Once the inflammatory disease process is controlled, patients with inflammatory Brown syndrome may show spontaneous resolution.
Congenital Brown syndrome
Congenital Brown syndrome is unlikely to improve spontaneously; therefore, surgery is important to consider as an option.
The most important indications for surgery are the presence of chin elevation and severe limitation of elevation in adduction, which significantly interferes with the quality of life. Acquired nontraumatic cases should initially be managed conservatively, because spontaneous resolution may occur. Consider surgery for long-standing cases.
The treatment of superior oblique Brown syndrome is to lengthen the tendon and release the restriction without causing a superior oblique palsy. The first phase is to identify the restriction's cause, inelastic superior oblique tendon or no superior oblique tendon (eg, fat adhesion). The most important signs of inelastic tendon etiology include positive forced duction that is worse with retropulsion, intorsion in upgaze, and negative forced duction after transecting the superior oblique tendon. The best surgical procedures lengthen the tendon rather than severing the tendon. The old procedure of tenotomy was associated with 50-80% risk for iatrogenic superior oblique palsy. The surgically caused superior oblique palsy is worse than the Brown syndrome in many cases.
This technique consists of elongating the superior oblique tendon by performing a tenotomy and then of inserting a segment (about 5 mm) of medical-grade silicone 240 retinal band between the cut ends of the tendon.
Silicone must be placed within the tendon capsule without disrupting the floor of the tendon capsule; otherwise, complications, such as postoperative adherence of the silicone to the sclera or spontaneous extrusion of the implant, may occur.
This technique has been effective.
The silicone tendon expander procedure is not easy to perform because tenotomy or tenectomy requires special surgical techniques.
Preoperative and postoperative images of a patient who underwent the silicone tendon expander procedure are shown below.
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This patient has the longest follow-up in the silicone tendon expander group at 11 years. A. Preoperative composite photograph of eye movements, showi....
Superior oblique split tendon lengthening technique
This technique splits the tendon on the nasal side of the superior rectus muscle. The halves of the tendon are removed and then joined to lengthen the tendon.
The function of the superior oblique tendon remains intact and the cut tendon ends are separated in a controlled manner.
Suture bridge ("chicken suture")
A nonabsorbable suture is placed to connect the cut ends of the superior oblique tendon, thus preventing a consecutive superior oblique palsy.
The suture bridge can act as a scaffold for scar that can reunite the cut tendon ends, thus resulting in an undercorrection with a significant residual Brown syndrome.
Tenotomy
This treatment has been relatively successful for primary superior oblique overaction in nonfusing patients. However, patients with bifoveal fusion do not tolerate induced postoperative cyclovertical deviations.
A major problem with this technique is the uncontrolled separation of tendon ends.
The incidence of postoperative superior oblique paresis is reported to be 50-80%.
Parks and Eutis added a simultaneous ipsilateral inferior oblique recession with a superior oblique tenotomy to reduce the incidence of a secondary superior oblique palsy.[10]
Use of a 5-6 mm suture bridge can keep the cut tendon ends from separating too much. Unfortunately, this suture bridge can act as scaffolding for fibrosis to reunite the cut tendon ends, resulting in undercorrections.
Superior oblique recession
This procedure produces a graded slackening of the tendon.
The results are mixed, because undercorrections are common.
The problem with recessing the superior oblique tendon is that it dramatically changes the characteristics of the superior oblique tendon insertions and alters its functional mechanics. This results in the postoperative complication of limited depression.
Superior oblique and trochlear luxation
Superior oblique and trochlear luxation consists of removing the tendon from the trochlea by luxating the trochlea. This procedure has been abandoned.
Clinical Context:
Inhibits inflammatory reaction and pain by decreasing the activity of the enzyme cyclooxygenase, which results in prostaglandin synthesis.
Have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known but may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.
Barbara L Roque, MD, DPBO, FPAO, Senior Partner, Roque Eye Clinic; Chief of Service, Pediatric Ophthalmology and Strabismus Section, Department of Ophthalmology, Asian Hospital and Medical Center; Active Consultant Staff, International Eye Institute, St Luke's Medical Center Global City
Disclosure: Nothing to disclose.
Specialty Editors
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute
Disclosure: Nothing to disclose.
Chief Editor
Edsel Ing, MD, MPH, FRCSC, Associate Professor, Department of Ophthalmology and Vision Sciences, University of Toronto Faculty of Medicine; Active Staff, Michael Garron Hospital (Toronto East Health Network); Consulting Staff, Hospital for Sick Children and Sunnybrook Hospital, Canada
Disclosure: Nothing to disclose.
Additional Contributors
Kenneth W Wright, MD, Director, Wright Foundation for Pediatric Ophthalmology and Strabismus Ophthalmology, Cedars-Sinai Medical Center; Clinical Professor of Ophthalmology, Keck School of Medicine of the University of Southern California
Disclosure: Received royalty from Titan Surgical for inventor; Received royalty from Oxford University Press for author; Received royalty from Springer for author.
Maria Gabriela Salvador, MD, MD,
Disclosure: Nothing to disclose.
Acknowledgements
Anastasios J Kanellopoulos, MD Assistant Program Director, Clinical Associate Professor, Department of Ophthalmology, Manhattan Eye, Ear, and Throat Hospital, New York University
Anastasios J Kanellopoulos, MD is a member of the following medical societies: American Academy of Ophthalmology, Association for Research in Vision and Ophthalmology, Eye Bank Association of America, and International Society of Refractive Surgery
Fundus torsion (direct view). The bottom set of fundus photographs represents downgaze; the center photographs, primary position; and the top photographs, upgaze. Note that in the top set of photographs, the left fundus is intorted as the foveal fixation is slightly above the top of the optic disc. Courtesy of Kenneth Wright, MD.
A 3-year-old patient with acquired right Brown syndrome. Marked limitation of elevation in adduction is present in the right eye. Pseudo-overaction of the left inferior oblique is present. Courtesy of Kenneth Wright, MD.
The same patient as in the image above, 6 years later. The patient shows normal eye movements, and no signs of Brown syndrome. A spontaneous resolution occurred over a 2-year period. Courtesy of Kenneth Wright, MD.
Composite photographs, showing left Brown syndrome with marked limitation of elevation in adduction. Courtesy of Kenneth Wright, MD.
This patient has the longest follow-up in the silicone tendon expander group at 11 years. A. Preoperative composite photograph of eye movements, showing right Brown syndrome. The patient underwent silicone tendon expander, 6 mm right eye. B. Postoperative photograph 3 years after surgery, showing full ocular motility. C. Postoperative photograph 11 years after surgery, showing continued normal ocular motility. Courtesy of Kenneth Wright, MD.
A 3-year-old patient with acquired right Brown syndrome. Marked limitation of elevation in adduction is present in the right eye. Pseudo-overaction of the left inferior oblique is present. Courtesy of Kenneth Wright, MD.
The same patient as in the image above, 6 years later. The patient shows normal eye movements, and no signs of Brown syndrome. A spontaneous resolution occurred over a 2-year period. Courtesy of Kenneth Wright, MD.
This patient has the longest follow-up in the silicone tendon expander group at 11 years. A. Preoperative composite photograph of eye movements, showing right Brown syndrome. The patient underwent silicone tendon expander, 6 mm right eye. B. Postoperative photograph 3 years after surgery, showing full ocular motility. C. Postoperative photograph 11 years after surgery, showing continued normal ocular motility. Courtesy of Kenneth Wright, MD.
Composite photographs, showing left Brown syndrome with marked limitation of elevation in adduction. Courtesy of Kenneth Wright, MD.
Fundus torsion (direct view). The bottom set of fundus photographs represents downgaze; the center photographs, primary position; and the top photographs, upgaze. Note that in the top set of photographs, the left fundus is intorted as the foveal fixation is slightly above the top of the optic disc. Courtesy of Kenneth Wright, MD.
Brown syndrome (inelastic superior oblique muscle-tendon complex)
Primary superior oblique overaction
Inferior oblique paresis
Limitation of elevation in adduction
Usually severe (-3 to -4)
Usually mild
Usually severe (-3 to -4)
Limitation of elevation on abduction
Common (mild to moderate)
No
No
Bilateral involvement
Rare (5-10%)
Common
Unusual
Vertical deviation
None or small (< 10 PD)
Bilateral small (< 10 PD)
Unilateral large (>10 PD)
Superior oblique overaction
None or minimal
Yes, marked
Yes, marked
Pattern
None or V-pattern Y-subtype with divergence in upgaze
A-pattern Lambda-subtype with divergence in downward gaze
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