title: Visual evoked potentials in migraine: Is the "neurophysiological hallmark" concept still valid?
abstract: OBJECTIVE
  Lack of habituation is considered a neurophysiological hallmark of migraine. However, the results of visual evoked potential (VEP) studies have been discrepant, possibly because of different stimulation parameters and lack of blinding. Hence, there is a need for independent confirmation of lack of VEP habituation in migraine. In this blinded study we applied 16' checks to supplement our previous findings with 8', 31', 62' and 65' checks.
  
  
  METHODS
  VEPs in 41 interictal migraineurs and 30 controls were compared. VEPs were recorded in six blocks of 100 single responses. Linear N70-P100 amplitude change over blocks (habituation slope) was compared with an independent samples Student's t-test.
  
  
  RESULTS
  Amplitude decline over blocks was observed in both groups. Habituation slope was not significantly different between controls (-0.43 ± 0.54 μV/block) and migraineurs (-0.29 ± 0.35 μV/block) (p=0.33).
  
  
  CONCLUSIONS
  VEP habituation with 16' checks did not differ in migraineurs and controls. This is in agreement with previous findings with other stimulation parameters. It is therefore unlikely that use of different stimulation parameters could explain the discrepant results of previous studies. No studies that applied blinding during recording of VEP have found lack of habituation in migraineurs.
  
  
  CONCLUSIONS
  Lack of VEP habituation cannot be considered a reliable neurophysiological hallmark in migraine.
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway. Electronic address: Petter.m.omland@ntnu.no.
authors.forename: Petter M
authors.initials: PM
authors.lastname: Omland
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway.
authors.forename: Martin
authors.initials: M
authors.lastname: Uglem
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Knut
authors.initials: K
authors.lastname: Hagen
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Mattias
authors.initials: M
authors.lastname: Linde
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Erling
authors.initials: E
authors.lastname: Tronvik
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Sand
mesh_terms: D000328:Adult; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D010775:Photic Stimulation / Q000379:methods*; D016037:Single-Blind Method; D055815:Young Adult
keywords: Habituation; Migraine; Visual evoked potentials