[Brown's atavistic superior oblique syndrome: etiology of different types of motility disorders in congenital Brown's syndrome].

The fibrotic strand, an atavistic superior oblique muscle, not only explains the typical Brown syndrome but also-by its variable insertion-different patterns of elevation deficits seen in atypical Brown syndrome. A 10 mm excision of the strand gives good functional results of abnormal head position (immediate in most cases) and even elevation in adduction (after 1 year in most cases).