Lack of cold pressor test-induced effect on visual-evoked potentials in migraine |
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Authors: | Gianluca Coppola Antonio Currà Mariano Serrao Cherubino Di Lorenzo Manuela Gorini Elisa Porretta Alessia Alibardi Vincenzo Parisi Francesco Pierelli |
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Institution: | 1. Department of Neurophysiology of Vision and Neurophthalmology, G. B. Bietti Eye Foundation, IRCCS, Via Livenza 3, 00198, Rome, Italy 2. Department of Neurological Sciences, Ospedale A. Fiorini-Polo Pontino, “Sapienza” University, Rome, Italy 3. University Centre for Adaptive Disorders and Headache (UCADH), “Sapienza” University of Rome, Polo Pontino, ICOT, Latina, Italy 4. IRCCS Neuromed, Pozzilli (IS), Italy 5. University of Rome “Campus Biomedico”, Rome, Italy
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Abstract: | In patients with migraine, the various sensory stimulation modalities, including visual stimuli, invariably fail to elicit
the normal response habituation. Whether this lack of habituation depends on abnormal activity in the sub-cortical structures
responsible for processing incoming information as well as nociception and antinociception or on abnormal cortical excitability
per se remains debateable. To find out whether inducing tonic pain in the hand by cold pressure test (CPT) alters the lack
of visual-evoked potential (VEP) habituation in migraineurs without aura studied between attacks we recorded VEPs in 19 healthy
subjects and in 12 migraine patients during four experimental conditions: baseline; no-pain (hand held in warm water, 25°C);
pain (hand held in cold water, 2–4°C); and after-effects. We measured P100 amplitudes from six blocks of 100 sweeps, and assessed
habituation from amplitude changes between the six sequential blocks. In healthy subjects, the CPT decreased block 1 VEP amplitude
and abolished the normal VEP habituation (amplitude decrease to repeated stimulation) in patients with migraine studied between
attacks; it left block 1 VEP amplitude and abnormal VEP habituation unchanged. These findings suggest that the interictal
cortical dysfunction induced by migraine prevents the cortical changes induced by tonic painful stimulation both during pain
and after pain ends. Because such cortical changes presumably reflect plasticity mechanisms in the stimulated cortex, our
study suggests altered plasticity of sensory cortices in migraine. Whether this abnormality reflects abnormal functional activity
in the subcortical structures subserving tonic pain activation remains conjectural. |
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Keywords: | Migraine Cold pressor test Visual-evoked potentials Habituation Brainstem Thalamo-cortical activity |
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