Case report: tenosynovitis of the left superior oblique muscle
Brown syndrome is defined as an ocular motility disorder, characterized by an inability to elevate the adducted eye actively or passively. The causes can be congenital or acquired, and the problem can be permanent or transient. Clinically, Brown syndrome is characterized by a significant limitation of elevation in the adducting position that occurs in the majority of cases and improved elevation is usually apparent in the midline, with generally normal elevation in abduction. Exodeviation (V pattern) can occur on elevation in the midline. Many patients are orthophoric in the primary position, although sometimes hypotropia can develop with a compensatory face turn towards the opposite eye. A positive forced duction test is usually the hallmark of Brown syndrome.
MRI and CT scans can sometimes have distinctive features for Brown syndrome3,4,5 such as thickening, abnormal enhancement or atrophy of the reflected portion of the superior oblique tendon and this aids in the diagnosis of the syndrome. Traditionally, treatment involved surgery, in congenital cases, or steroid therapy, in acquired cases.
She was first seen in the eye clinic with visual acuity of 2/60 in the right eye and 6/36 in the left, improving to 6/6-1 in the right eye and 6/4-1 in the left with her own myopic glasses. She only had a family history of myopia with no significant past medical or ophthalmic history.
Cover test with her glasses showed mild esophoria with good recovery for near vision and orthophoria for distance vision. Ocular movement examination showed moderate limited elevation on adduction in both eyes, more in the left than the right, along with minimal limitation on adduction in both eyes, more in the left than the right. She was fully binocular, and Frisby test with her glasses was 85 seconds. Prism fusion range with her glasses was 20 BO prism dioptres (D) - 4 BI prism D for near vision. Prism cover test with the glasses was less than 2 BO prism D for near and zero for distance.
Hess chart on presentation date showed overactivity of superior rectus, superior oblique muscles and underactivity of the medial rectus muscle in the right eye. The left eye showed underactivity of both inferior oblique and superior rectus muscles.
The orthoptic department concluded the case as acquired, bilateral, asymmetrical Brown syndrome with medial rectus underaction. The rest of the ocular examination did not show any abnormalities with normal intraocular pressure and normal fundus in both eyes.
And the treatment...
The patient was initiated on oral ibuprofen therapy (200 mg, twice per day) and she was scheduled for a CT scan.
