Bilateral superior oblique tendon sheath syndrome. Occurrence and spontaneous recovery in one of uniovular twins.

Brown (I950) defined the features of the superior oblique tendon sheath syndrome and reported five cases. He postulated that the restriction in elevation of the affected eye in the adducted position was caused by a congenitally short anterior tendon sheath of the superior oblique muscle. As the eye moved into adduction, this ligament-like sheath became taut and strongly opposed the action of the inferior oblique muscle. By surgery, he showed the forced duction test for elevation in adduction was positive until the superior oblique tendon sheath was cut; the forced duction test then became negative as the eye could be fully elevated. Some of Brown's early cases were treated by excision of the superior oblique tendon sheath, but in his later thesis (Brown, 1957) he advised that surgery should not be performed unless the patient had a deforming head tilt. Excision of the fibrotic superior oblique tendon sheath did not usually lead to improved function of the inferior oblique muscle. Nutt (I954 I955) and Nutt and Mein (I963) favoured surgery, especially if a head tilt were present, but admitted that the results were not always what one would hope for, and that, to a certain extent, slow and spontaneous improvement occurred. Costenbader and Albert (I 958) were the first to report a case showing spontaneous regression of pseudoparalysis of the inferior oblique muscle. Adler (I959) added another case. At the Strabismus Symposium of the New Orleans Academy of Ophthalmology, Brown (I962) reported that, of sixty of his own patients with the superior oblique tendon sheath syndrome, only three had outgrown it and that he had seen several adults with this condition. The present case is the first to be reported with spontaneous recovery from a bilateral superior oblique tendon sheath syndrome, and its occurrence in only one of uniovular twins is an added feature of interest.