title: Correlation between habituation of visual-evoked potentials and magnetophosphene thresholds in migraine: A case-control study.
abstract: BACKGROUND
  In migraine most studies report an interictal deficit of habituation of visual-evoked potentials (VEP-hab) and reduced thresholds for phosphene induction (PT) by transcranial magnetic stimulation (TMS). We searched for a possible correlation between VEP-hab and PT in migraine patients and healthy controls to test whether they reflect the same pathophysiological abnormality.
  
  
  METHODS
  We assessed PT and VEP-hab measured as the percentage change of N1/P1 amplitude over six blocks of 100 responses in 15 healthy volunteers (HV) and in 13 episodic migraineurs without aura (MO) between attacks. Results were compared using Mann-Whitney U test. Interrelationships were examined using Spearman's correlation.
  
  
  RESULTS
  In MO patients VEP-hab was reduced compared to HV (p = 0.001), while PT were not significantly different between HV and MO. There was no correlation between PT and VEP-hab in either group of participants.
  
  
  CONCLUSIONS
  We confirm that in interictal migraine VEP habituation is deficient, but magnetophosphene threshold normal. VEP-hab and PT were not correlated with each other in healthy controls or in migraineurs. This finding suggests that they index different facets of cortical excitability in migraine, i.e. a punctual normal measure of the cortical activation threshold for PT and a dynamic response pattern to repeated stimuli for VEP habituation.
authors.affiliation: IRCCS Neuromed, Headache Unit, Italy anna.ambrosini@neuromed.it.
authors.forename: Anna
authors.initials: A
authors.lastname: Ambrosini
authors.affiliation: IRCCS Neuromed, Clinical Neurophysiology Unit, Italy.
authors.forename: Ennio
authors.initials: E
authors.lastname: Iezzi
authors.affiliation: IRCCS Neuromed, Headache Unit, Italy.
authors.forename: Armando
authors.initials: A
authors.lastname: Perrotta
authors.affiliation: IRCCS San Raffaele Pisana, Unit of Clinical and Molecular Epidemiology, Italy.
authors.forename: Aliaksei
authors.initials: A
authors.lastname: Kisialiou
authors.affiliation: IRCCS Neuromed, Clinical Neurophysiology Unit, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Nardella
authors.affiliation: IRCCS Neuromed, Clinical Neurophysiology Unit, Italy Sapienza University of Rome, Department of Neurology and Psychiatry, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Berardelli
authors.affiliation: IRCCS Neuromed, Headache Unit, Italy Sapienza University of Rome, Department of Medical-Surgical Sciences and Biotechnologies, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pierelli
authors.affiliation: University of Liège - CHR Citadelle, University Dept. of Neurology, Headache Research Unit, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Schoenen
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000503:physiopathology*; D010719:Phosphenes / Q000502:physiology*; D010775:Photic Stimulation; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Migraine; cortical excitability; habituation; magnetophosphene threshold; visual-evoked potentials