Contingent negative variation--findings and perspectives in migraine.

Contingent negative variation (CNV) is a negative cerebral potential which is related to attention and arousal. CNV occurs during an experimental situation in which stimuli and responses are serially organized. Between attacks migraine patients have on average higher negative amplitudes compared to healthy controls or patients with tension-type headache. Successful treatment with beta-blocking agents decreases CNV amplitudes. In spite of encouraging findings in neurological disorders, CNV is not widely used. In this review some possible reasons for this are pointed out.