title: Visual cortex hyperexcitability in idiopathic generalized epilepsies with photosensitivity: a TMS pilot study.
abstract: BACKGROUND
  The current understanding of the mechanisms underlying photosensitivity is still limited, although most studies point to a hyperexcitability of the visual cortex.
  
  
  METHODS
  Using transcranial magnetic stimulation, we determined the resting motor threshold (rMT) and the phosphene threshold (PT) in 33 patients with IGEs (8 with photosensitivity) compared with 12 healthy controls.
  
  
  RESULTS
  Eleven controls (92%) reported phosphenes compared with fifteen (46%) patients with idiopathic generalized epilepsy (p=0.015). Phosphenes were reported more frequently among patients with epilepsy with photosensitivity (87.5%) than in patients with active epilepsy without photosensitivity (30.8%) (p=0.038) and patients with epilepsy in remission without photosensitivity (33.3%) (p=0.054); no differences were found between patients with epilepsy with photosensitivity and controls (p=0.648). Resting motor threshold and phosphene threshold were significantly higher among patients with epilepsy (active epilepsy or epilepsy in remission without photosensitivity) compared to healthy controls (p<0.01). Conversely, patients with active epilepsy and photosensitivity had significantly lower values than controls (p=0.03).
  
  
  CONCLUSIONS
  The marked decrease in PT and the high phosphene prevalence in patients with IGE with photosensitivity indicate a regional hyperexcitability of the primary visual cortex. Results of this study also suggest that the PT may serve as a biomarker for excitability in patients with IGE and photosensitivity.
authors.affiliation: Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Clinical Neurology, University of Verona, Italy. dr.francescobrigo@gmail.com
authors.forename: Francesco
authors.initials: F
authors.lastname: Brigo
authors.forename: Luigi Giuseppe
authors.initials: LG
authors.lastname: Bongiovanni
authors.forename: Raffaele
authors.initials: R
authors.lastname: Nardone
authors.forename: Eugen
authors.initials: E
authors.lastname: Trinka
authors.forename: Frediano
authors.initials: F
authors.lastname: Tezzon
authors.forename: Antonio
authors.initials: A
authors.lastname: Fiaschi
authors.forename: Paolo
authors.initials: P
authors.lastname: Manganotti
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D004829:Epilepsy, Generalized / Q000150:complications / Q000473:pathology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010719:Phosphenes / Q000502:physiology*; D010787:Photosensitivity Disorders / Q000150:complications / Q000473:pathology*; D010865:Pilot Projects; D012684:Sensory Thresholds; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000503:physiopathology*; D055815:Young Adult