Five patients with long-standing episodic vertigo and ocular motor signs are reported from the Department of Neurology, UCLA School of Medicine, Los Angeles, CA. Because of the clinical similarity to the familial periodic ataxia syndromes, these patients and affected family members were treated with acetazolamide. The episodic vertigo was either abolished or markedly decreased in frequency and severity. The age of onset of the vertigo varied from age two to 32. The episodes lasted from several hours to several days and were complicated by nausea and vomiting and later, a mildly progressive ataxia. Associated symptoms included horizontal or vertical diplopia, slurred speech, and positional downbeat and rebound nystagmus between attacks. The findings suggested a lesion of the vestibulocerebellum. In seven patients examined the MRI was normal. [1]

COMMENT. The familial periodic ataxia syndromes have been divided into two types, 1) a vestibulocerebellar syndrome and 2) diffuse cerebellar ataxia, as described by Parker, in which vertigo is infrequent and ataxia is more pronounced. Both syndromes appear to respond to acetazolamide.