title: Effect of levetiracetam on cortical excitability: a transcranial magnetic stimulation study.
abstract: OBJECTIVE
  We studied the effect of levetiracetam (LEV), an anticonvulsant with a novel mechanism of action, on cortical excitability, measured using transcranial magnetic stimulation (TMS). For this purpose, 38 healthy volunteers were assessed in two TMS sessions, before and after an oral dose of 3000 mg LEV.
  
  
  METHODS
  Resting motor threshold (RMT), intracortical facilitation (ICF) and intracortical inhibition (ICI), cortical silent period (CSP) threshold and duration and motor-evoked potential (MEP) amplitude were calculated.
  
  
  RESULTS
  After treatment with LEV, RMT was increased (mean +/- SD: 63 +/- 14% of the maximum stimulator output) compared with baseline (58 +/- 11%). CSP threshold was decreased after LEV (54 +/- 10%; baseline, 57 +/- 11%). CSP duration was increased after LEV (116 +/- 37 ms; baseline: 102 +/- 33 ms). LEV did not affect ICF or ICI or mean MEP amplitude significantly.
  
  
  CONCLUSIONS
  Our results indicate that LEV modulates some aspects of cortical excitability. Whereas the increase in the RMT most probably reflects the effect of LEV on ion channel activity, effects on the CSP might represent a modulation of GABA receptors at cortical and spinal level.
authors.affiliation: Southern Clinical School, Monash University, Clayton, Vic., Australia.
authors.forename: C
authors.initials: C
authors.lastname: Solinas
authors.forename: Y C
authors.initials: YC
authors.lastname: Lee
authors.forename: D C
authors.initials: DC
authors.lastname: Reutens
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004056:Differential Threshold / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D019054:Evoked Potentials, Motor / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D005260:Female; D006801:Humans; D000077287:Levetiracetam; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000187:drug effects* / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D018697:Nootropic Agents / Q000494:pharmacology*; D010889:Piracetam / Q000031:analogs & derivatives* / Q000494:pharmacology; D050781:Transcranial Magnetic Stimulation
chemical_list: D018697:Nootropic Agents; D000077287:Levetiracetam; D010889:Piracetam