A 3-Year-Old Girl Whose Eyes Appear Misaligned

Zane D. Foster; Kimberly G. Yen, MD; Madhuri Chilakapati, MD

Disclosures

July 26, 2019

Discussion

The cause of Brown syndrome was thought to be a tight superior oblique tendon sheath; however, over the years, careful examination of patients with the syndrome revealed that this is not likely the case. Brown syndrome can result from any structural abnormality involving the superior oblique muscle or trochlea, which makes it difficult to elevate the affected eye while it is adducted. The characteristic feature of the syndrome is unilateral limitation of elevation in adduction. There is a linear reduction in elevation deficit as the eye is abducted to the point where there is minimal to no deficit in full abduction.

Brown syndrome is subdivided into mild (characterized by orthotropia in primary and horizontal gaze), moderate (characterized by the presence of downshoot in horizontal adduction), and severe (characterized by hypotropia in primary gaze).[1,2] In more severe cases, the ipsilateral palpebral fissure may widen with adduction.[1,2,3] Additionally, in up to one third of patients, there may be an abnormal head posture, most commonly chin-up presentation and less commonly a contralateral face turn.[2,4] This abnormal head posturing occurs because the patient consistently turns his or her head away from the affected eye to reduce the diplopia caused by the ocular deviation.[5,6]

Brown syndrome must be distinguished from inferior oblique palsy, a less common condition that also presents with an inability to elevate the eye on adduction. The two conditions may be distinguished with a forced duction test in which the eye is passively moved with forceps to evaluate restriction. In Brown syndrome, the forced duction test would demonstrate restriction to elevation in adduction, whereas with an inferior oblique palsy, the forced duction test would reveal no elevation restriction. Other findings that distinguish an inferior oblique palsy from Brown syndrome include hypotropia in primary gaze, superior oblique muscle overaction, and intorsion on fundus examination. A forced duction test is generally performed under anesthesia in pediatric patients.

Furthermore, distinguishing between acquired Brown syndrome and congenital Brown syndrome is important because the treatment and prognosis differ.

Acquired Brown syndrome occurs secondary to conditions after infancy. Any condition that interferes with the superior oblique's movement through the trochlea may produce this syndrome—from inflammatory conditions (eg, juvenile rheumatoid arthritis,[7]systemic lupus erythematosus,[8] scleroderma[9]) to impinging tumors, infections,[10] postsurgical complications, or traumatic injury.[2,11] Depending upon the specific etiology, acquired Brown syndrome can be responsive to treatment, and some patients may even undergo spontaneous recovery.[12] The treatment should focus on the underlying condition. For example, if the condition is caused by a tumor impinging on the trochlea, removal of the tumor generally resolves the Brown syndrome; if the condition is caused by an orbital inflammatory syndrome, prompt steroid administration may resolve it.[11]

Congenital Brown syndrome is encountered more commonly than the acquired form[4]; however, there is no clear genetic basis or inheritance pattern for the disorder. Although this form does not often spontaneously resolve,[2,3] mild cases generally do not impact a patient's daily life. Observation is usually sufficient; for severe cases, surgery can be recommended. Nonsurgical treatments such as steroid injections are not typically useful.[2]

Surgical management of Brown syndrome is indicated only in moderate to severe cases.[1,2,3] Available surgical options include superior oblique tendon expander, "chicken suture," and exaggerated forced traction. Surgical procedures on the superior oblique such as tenectomy or tenotomy are often complicated by postoperative superior oblique palsy.[13,14,15] This has historically been managed through a subsequent superior oblique muscle resection, but more modern techniques involve preventing postoperative complications via either simultaneous recession of the inferior oblique muscle or placement of a 5- to 8-mm silicone expander during tenotomy.[1]

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