Auditory brain-stem responses in Marcus Gunn ptosis.

The auditory brain-stem response (ABR) can detect anomalies both in the auditory pathways and in structures adjacent to these pathways. Patients with Duane's retraction syndrome, associated with hypoplasia of the abducens nerve in the brain-stem, and patients with hemifacial spasm, due to compression of the facial nerve in the brain-stem, have been found to have abnormal ABRs. Marcus Gunn ptosis with 'jaw winking' is considered to be due to misconnection of oculomotor, trigeminal and other cranial nerves. Suspecting that perhaps some 'jaw-winking' phenomena may be due to detectable brain-stem anomalies we tested 7 patients with Marcus Gunn ptosis. Three of the patients demonstrated abnormal ABRs indicative of pontine pathology.