Abstract
BackgroundThe migraine brain seems to undergo cyclic fluctuations of sensory processing. For instance, during the preictal phase, migraineurs experience symptoms and signs of altered pain perception as well as other well-known premonitory CNS-symptoms. In the present study we measured EEG-activation to non-painful motor and sensorimotor tasks in the different phases of the migraine cycle by longitudinal measurements of beta event related desynchronization (beta-ERD).MethodsWe recorded electroencephalography (EEG) of 41 migraine patients and 31 healthy controls. Each subject underwent three EEG recordings on three different days with classification of each EEG recording according to the actual migraine phase. During each recording, subjects performed one motor and one sensorimotor task with the flexion-extension movement of the right wrist.ResultsMigraine patients had significantly increased beta-ERD and higher baseline beta power at the contralateral C3 electrode overlying the primary sensorimotor cortex in the preictal phase compared to the interictal phase. We found no significant differences in beta-ERD or baseline beta power between interictal migraineurs and controls.ConclusionIncreased preictal baseline beta activity may reflect a decrease in pre-activation in the sensorimotor cortex. Altered pre-activation may lead to changes in thresholds for inhibitory responses and increased beta-ERD response, possibly reflecting a generally increased preictal cortical responsivity in migraine. Cyclic fluctuations in the activity of second- and third-order afferent somatosensory neurons, and their associated cortical and/or thalamic interneurons, may accordingly also be a central part of the migraine pathophysiology.
Highlights
Migraine patients undergo transient clinical and neurophysiological changes before, during and after headache attacks
Paired analyses for preictal, ictal and postictal phases compared to the interictal period Paired comparison (Table 2) revealed significantly increased beta-Event-related desynchronization (ERD) responses in contralateral sensorimotor cortex (C3) in the preictal phase compared to the interictal phase for both the sensorimotor test (SM) and M-tasks (C3 SM, p = 0.038; C3 M, p = 0.049; Fig. 3)
Paired Student’s t-tests for baseline (Table 4) revealed significantly increased beta power in contralateral sensorimotor cortex (C3) in the preictal phase compared to the interictal phase for both the SM and M-tasks (C3 SM, p = 0.007; C3 M, p = 0.048)
Summary
Migraine patients undergo transient clinical and neurophysiological changes before, during and after headache attacks. Event related desynchronization and synchronization (ERD/ERS) are electrophysiological features that represent an induced, time-locked, nonphase-locked response to events These responses are subject to changes in neuronal synchrony. One study of fibromyalgia patients showed altered beta-ERD in response to tactile stimulation, which was interpreted by the authors as physiological changes that contribute to chronic pain in this patient group [31]. This technique may be useful for investigating cortical sensory processing in migraine patients. In the present study we measured EEG-activation to non-painful motor and sensorimotor tasks in the different phases of the migraine cycle by longitudinal measurements of beta event related desynchronization (beta-ERD)
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