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An estimated one-fourth to one-third of patients with migraine will experience vertigo associated with their migraine attacks. Vestibular migraine frequently presents as a diagnostic challenge as objective neurological findings consistent with this entity have not been well described.The aim of this study is to characterize eye movements of patients presenting with nystagmus during attacks of migrainous vertigo.A retrospective study of 26 patients presenting with nystagmus during an acute vestibular migraine was performed. All patients were examined while symptomatic during a migraine spell, and also while asymptomatic. All patients underwent tests of vestibular function with either bithermal water caloric or rotary chair electronystagmography.The most common patient was a female of perimenopausal age. Spontaneous nystagmus was seen in 19% of patients and nystagmus provoked by horizontal headshaking was seen in 35%. Nystagmus could be provoked with positional testing in 100% of symptomatic patients with fixation blocked. The positional nystagmus most commonly was sustained, of low velocity, and could be horizontal, vertical or torsional. Bithermal water caloric or rotary chair tests obtained during symptom-free intervals were normal in all patients.Although nystagmus characteristics are quite variable during vestibular migraine, the finding on examination of low-velocity, sustained nystagmus with positional testing in a young to middle-aged adult patient presenting with vertigo, nausea and headache is highly suggestive of vestibular migraine as long as the nystagmus dissipates when the patient is free of symptoms.