Idiopathic superior oblique palsies in children.

The records of 110 patients with superior oblique palsy seen at the Boston Children's Hospital between 1966 and 1988 were reviewed. Patients with identifiable orbital or neurological disorders affecting the fourth cranial nerve or with a history of head trauma preceding their superior oblique palsy were excluded from analysis. Patients were also excluded because of prior surgery elsewhere or insufficient diagnostic information. The remaining 63 patients were considered to have idiopathic superior oblique palsies. All 63 patients presented with unilateral palsies. All had incomitant hypertropia of the affected eye, greater on gaze to the contralateral side and increased by ipsilateral head tilt. Left eyes were affected in 41 patients. The age at first ophthalmological examination was spread over the first 20 years, with heavier representation in the first 5 years and decreasing numbers in each succeeding 5-year interval. Only one patient was found to have a masked bilateral superior oblique palsy following surgery for an apparent unilateral palsy. A distinction is made between unmasking a bilateral superior oblique palsy and surgical overcorrection of a unilateral palsy. The predominant unilaterality of idiopathic superior oblique palsies is in contrast to the reported frequency of bilaterality in traumatic cases.