title: Photic EEG-driving responses related to ictal phases and trigger sensitivity in migraine: a longitudinal, controlled study.
abstract: BACKGROUND
  Photic driving is believed to be increased in migraineurs and has been interpreted as a sign of cortical hyperexcitability. However, most previous studies have included patients in various phases of the migraine cycle. The results are, therefore, difficult to interpret as neurophysiological abnormalities tend to accumulate close to the attack in migraineurs.
  
  
  METHODS
  We recorded steady state visual evoked EEG-responses (SSVEPs) for 6, 12, 18 and 24 Hz flash stimuli from 33 migraineurs without aura, eight migraineurs with aura and 32 healthy controls. Interictal recordings were compared pair-wise with recordings before, during and after attack, as well as with EEGs from healthy controls. Driving power was also correlated with sensory hypersensitivity and severity of migraine.
  
  
  RESULTS
  Between attacks, driving responses to 18 Hz and 24 Hz were attenuated in migraineurs without aura. Driving power of 12 Hz increased before the attack. Attack trigger sensitivity, photophobia, pain intensity and a family history of migraine were related to decreased and/or symmetric photic driving.
  
  
  CONCLUSIONS
  Earlier results may have overestimated the driving response in migraine due to inclusion of recordings during the preictal interval and/or habituation among controls. Abnormal photic driving may be related to the pathophysiology of clinical sensory hypersensitivity.
authors.affiliation: Norwegian University of Science and Technology, Norway. marte.bjork@ntnu.no
authors.forename: M
authors.initials: M
authors.lastname: Bjørk
authors.forename: K
authors.initials: K
authors.lastname: Hagen
authors.forename: Lj
authors.initials: Lj
authors.lastname: Stovner
authors.forename: T
authors.initials: T
authors.lastname: Sand
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004569:Electroencephalography / Q000379:methods*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008027:Light / Q000009:adverse effects; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D010775:Photic Stimulation / Q000009:adverse effects*; D055815:Young Adult