Migraine equivalent as a cause of episodic vertigo.

There are many transient neurologic disturbances associated with various types of migraine. Visual symptoms, such as scintillating scotomata are most common, but somatosensory, motor, cranial nerve, and brain stem symptoms also occur. Among the brain stem symptoms, vestibular manifestations are quite common and include nonspecific dizziness, disequilibrium, vertigo, and motion intolerance. Auditory symptoms are less common. These transient neurologic symptoms can precede the headache as an aura, can occur during the headache, or, uncommonly, can immediately follow the headache. It is also well documented that the neurologic symptoms can occur in the period between headaches, a situation termed "migraine equivalent." Migraine equivalents usually occur in patients who have experienced typical migraine headaches earlier in life or who have migraine headaches at times other than when they experience equivalent symptoms. Rarely, typical migraine equivalent symptoms precede the development of the headaches by months or years, or occur in individuals who never develop headaches. Five patients with migraine equivalent symptoms that include vertigo are presented. The vertigo was the dominant symptom in some cases and was accompanied by nausea and vomiting. Differentiation from peripheral labyrinthine disorders is difficult, but a personal or family history of migraine, the temporal association of the neuro-otologic symptoms with other migraine equivalent symptoms, a characteristic pattern of occurrence of the symptoms, and a positive response to antimigrainous therapy are features that strengthen the diagnosis of a migraine equivalent phenomenon.