Vestibular studies in Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease is a rare sex-linked recessive neurological disorder. It presents with a slowly progressive neurological deterioration. It is liable to be misdiagnosed as cerebral palsy. A family history of similar disease is a clue to the diagnosis. A patient with this condition has been followed over many years. Nystagmus was noted to be present shortly after birth. Audiovestibular investigations were performed. All tests of peripheral hearing were normal. ABR indicated abnormal brainstem conduction. Several electronystagmographic abnormalities were present. These were of a central type. They included failure of fixation suppression, poor smooth pursuit, and impaired performance of optokinetic nystagmus at high stripe speeds. During caloric-induced nystagmus an excessively prolonged slow phase of nystagmus with wide eye excursions was seen. We have not seen this feature in any other diseases and we suggest it may be specific for this syndrome.