Interictal lack of habituation of mismatch negativity in migraine

Authors


Marina de Tommaso, Clinica Neurologica I, Policlinico Piazza Giulio Cesare 11, 70124 Bari, Italy. Tel. +39 0805 478565, Fax: +39 0805 478565/0805 478532, e-mail m.detommaso@neurol.uniba.it

Abstract

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The aim was to study mismatch negativity features and habituation during the interictal phase of migraine. In migraine patients, a strong negative correlation has been found between the initial amplitude of long latency auditory-evoked potentials and their amplitude increase during subsequent averaging. We studied 12 outpatients with a diagnosis of migraine without aura recorded in a headache-free interval and 10 gender- and age-matched healthy volunteers not suffering from any recurrent headache. The experiment consisted of two sequential blocks of 2000 stimulations, during which 1800 (90%) recordings for standard tones and 200 (10%) for target tones were selected for averaging. The latency of the N1 component was significantly increased in migraine patients in respect of controls in both the first and second repetitions; the MMN latency was increased in the second repetition. In the control group the MMN amplitude decreased on average by 3.2 ± 1.4 µV in the second trial, whereas in migraine patients it showed a slight increase of 0.21 ± 0.11 µV in the second repetition. The MMN latency relieved in the second trial was significantly correlated with the duration of illness in the migraine patients (Spearman correlation coefficient: 0.69; P < 0.05). The increases in N1 latency and MMN latency and amplitude, the latter correlated with duration of illness, seemed to be due to a reduced anticipatory effect of stimulus repetition in migraine patients. This suggests that such hypo-activity of automatic cortical processes, subtending the discrimination of acoustic stimuli, may be a basic abnormality in migraine, developing in the course of the disease.

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