MR imaging of familial superior oblique hypoplasia.

BACKGROUND Congenital superior oblique palsy is usually associated with a structural abnormality of the superior oblique tendon. There have been many reports of familial congenital superior oblique palsy. However, there has been no MRI documentation of familial superior oblique hypoplasia. METHODS Ophthalmological examination and orbital MRI were performed in three patients in a pedigree with familial superior oblique palsy. They showed typical signs of superior oblique palsy, including superior oblique underaction and overelevation in adduction on the affected side, torticollis in the early part of life, and positive head tilt testing. RESULTS Moderate to severe superior oblique hypoplasia was identified in all three affected family members. CONCLUSION Superior oblique hypoplasia confirmed with MRI was useful for clarifying the aetiology of familial superior oblique palsy.