title: Altered recovery from inhibitory repetitive transcranial magnetic stimulation (rTMS) in subjects with photosensitive epilepsy.
abstract: To investigate functional changes underlying photosensitivity, we studied the response of the visual cortex to low-frequency, inhibitory repetitive transcranial magnetic stimulation (rTMS) in drug-free patients with photosensitive seizures and healthy volunteers.
  
  
  
  Visual evoked potentials (VEPs) triggered by grating stimuli of different contrasts were recorded in both hemispheres before and after transient functional inactivation of the occipital cortex of one side via low-frequency rTMS (0.5Hz for 20'). VEPs were recorded before (T0), immediately after (T1) and 45' following the completion of rTMS (T2).
  
  
  
  Baseline amplitudes of the early VEP components (N1 and P1) were enhanced in photosensitive patients. At T1, rTMS produced an inhibitory effect on VEPs amplitudes at all contrasts in the targeted side and a concurrent facilitation of responses in the contralateral hemisphere. Compared with PSE subjects, VEP amplitudes remained persistently dampened in the stimulated hemisphere of controls (Holm-Sidak post-hoc method, p<0.05). In the contralateral hemisphere, we found a clear enhancement of VEP amplitude in photosensitive subjects but not controls at T2 (Holm-Sidak test, p<0.001).
  
  
  
  Visual responses recovered more quickly in the stimulated hemisphere, and disinhibition persisted in the contralateral side of photosensitive subjects.
  
  
  
  The rapid recovery of excitability and the persistent transcallosal disinhibition following perturbation of cortical activity may play a role in the pathophysiology of photosensitive epilepsy.
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Neurology, Pisa University, Pisa, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Bocci
authors.affiliation: CNR Institute of Neuroscience, Pisa, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Caleo
authors.affiliation: CNR Institute of Neuroscience, Pisa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Restani
authors.affiliation: CNR Institute of Neuroscience, Pisa, Italy; DAI of Neuroscience, Cisanello Neurology Unit, AOUP, Pisa, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Barloscio
authors.affiliation: Department of Medical and Surgical Science and Neuroscience, Unit of Neurology and Clinical Neurophysiology Brain Investigation & Neuromodulation Lab., Azienda Ospedaliera Universitaria Senese, Siena, Italy; Human Physiology Section, Department of Medical and Surgical Science and Neuroscience, University of Siena, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Rossi
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Neurology, Pisa University, Pisa, Italy; CNR Institute of Neuroscience, Pisa, Italy; DAI of Neuroscience, Cisanello Neurology Unit, AOUP, Pisa, Italy. Electronic address: ferdinando.sartucci@med.unipi.it.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Sartucci
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D020195:Epilepsy, Reflex / Q000503:physiopathology*; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000503:physiopathology
keywords: Corpus callosum; Long term depression; Photo-paroxysmal response; Photosensitivity; Visual system