Chronic migrainous vertigo.

A series of 16 subjects is described who presented with chronic vertigo that was thought to be migrainous in nature. The vertigo occurred on a daily basis and had been present for six months or more. Common symptoms included motion-induced dizziness, positional vertigo and motion sensitivity. Investigations were frequently normal apart from the finding of atypical positional nystagmus in four subjects and unilateral vestibular hypofunction in two subjects. It was frequently not possible to make a diagnosis of migraine on the basis of International Headache Society criteria, however the dramatic beneficial response to anti-migraine therapy supported the hypothesis that the vertigo was migrainous in nature.