Disease duration of episodic migraine correlates with modified amplitudes and habituation of contingent negative variation.

Cortical habituation in episodic migraine patients without medication overuse headache (MOH), recorded by contingent negative variation (CNV), is often reduced compared with healthy controls. There is evidence that with longer duration of migraine disease (DOD) amplitudes and habituation of CNV become progressively abnormal. The aim of the study was to examine habituation characteristics of contingent negative variation in episodic migraine patients suffering from short- and long-lasting migraine compared to matched healthy controls. 32 migraine patients without aura and without MOH diagnosed according to the revised ICHD-II criteria and 16 age- and sex-matched healthy controls were included. According to DOD, the total sample of migraine patients was divided into two groups (group a: DOD <121 months, n = 17 subjects, group b: DOD >120 months, n = 15 subjects). Both migraine groups did not differ in the number of days of migraine and the duration of attacks. Overall CNV and initial CNV differed significantly between migraine patients and controls, whereas the former produced more negative amplitudes. In the migraine group lack of or deficient habituation occurred, whilst controls showed habituation. There were middle range correlations between the DOD and overall CNV, initial CNV, and y-intercept. Patients suffering from long-lasting migraine produced higher CNV amplitudes with a higher y-intercept. The results are interpreted as "maladaptive plasticity" with a risen intercept in long-lasting migraine.