Electrophysiological response patterns of primary sensory cortices in migraine

Abstract

Migraine is an ictal disorder characterised by a particular vulnerability of patients to sensory overload, both during and outside of the attack. Central nervous system dysfunctions are supposed to play a pivotal role in migraine. Electroneurophysiological methods, which aim to investigate sensory processing, seem thus particularly appropriate to study the pathophysiology of migraine. We have thus reviewed evoked potential studies performed in migraine patients. Although results are in part contradictory, these studies nonetheless demonstrate an interictal dysfunction of sensory cortices, and possibly of subcortical structures, in migraine with and without aura. The predominant abnormality is a deficient habituation of evoked responses to repeated stimuli, probably due to cortical, and possibly widespread neural, "dysexcitability".

Diagnosis, pathophysiology and management of chronic migraine: a proposal of the Belgian Headache Society

“…It is generally accepted that the common forms of migraine with or without aura (Table 2): abnormal thickness, connectivity and/or activation of certain cortical and subcortical areas [24][25][26][27], increased transmitter [28] or iron content [29][30][31], decreased ATP content [32,33] and an abnormal pattern of sensory processing [34,35]. The latter is characterized by low amplitude of initial responses and hyperresponsivity with lack of habituation of late responses during repeated sensory stimuli [36], and has been attributed to a thalamocortical dysrhythmia caused by deficient monoaminergic control by brain stem nuclei (review in [37]).…”

Stimulating studies of visual cortical function in migraine

“…Migraine patients have been commonly reported to have a reduced habituation of cortical responses, i.e. the reduction in the responses to a second stimulus following an initial stimulus does not occur to the same degree in migraine patients as compared with controls (8,9). However, there are differing views regarding whether baseline cortical excitability is increased or decreased in migraine.…”

“…Some of the discrepancies in different studies could, therefore, be a reflection of the fact that cortical excitability in migraine patients is more widely variable than it is in controls (23). Thus, rather than simply increased or reduced excitability, migraine may be associated with a dysregulation of cortical function leading to excessive swings in either direction (24,25).…”

Perceptual illusions provide clues to excitatory–inhibitory balance in migraine neocortex

“…It could reflect a cortex with reduced glutamate stores. Or it could mean a cortex, the excitability of which has been down-regulated in some way by one of the many neuromodulators acting upon it, the role suggested for serotonin (6).…”

“…effects can be seen in a second sensory system -audition. In this, their work was motivated by the observation that electrophysiological abnormalities following habituation occur not only in vision, but also in audition and somatosensation (6).…”