Idiopathic generalized epilepsy: magnetic stimulation of motor cortex time-locked and unlocked to 3-Hz spike-and-wave discharges.
In 20 patients with idiopathic generalized epilepsy who showed typical 3-Hz spike-and-wave (SW) EEG complexes, we studied the corticospinal motor output with a transcranial electromagnetic stimulator. First we measured the corticospinal discharge threshold for both hemispheres in the patient group and compared it with that of 10 age- and sex-matched volunteers. Threshold was significantly higher in the patient group, regardless of whether subjects were treated with antiepileptic drugs (AEDs). In 4 patients with very frequent SW paroxysms, we were able to study motor evoked potential (MEP) changes time-locked to epileptic EEG transients. The EEG signal was recorded bipolarly (C3-P3, C4-P4) by scalp needle-electrodes. For a given stimulus intensity, we collected and measured MEPs occurring during the spike or the wave portion of the SW complexes. Data were compared with those of MEPs obtained time-locked to normal EEG segments. MEP size was significantly decreased when the cortical stimulus was time-locked to the wave component, and was decreased or unchanged when the stimulus was time-locked to the spike. Magnetic stimulation never produced remarkable side effects.
Gianelli
M
M
University Department of Neurology, Ospedale Maggiore, Novara, Italy.
Cantello
R
R
Civardi
C
C
Naldi
P
P
Bettucci
D
D
Schiavella
M P
MP
Mutani
R
R
D000328:Adult; D000927:Anticonvulsants / Q000494:pharmacology / Q000627:therapeutic use; D004569:Electroencephalography / Q000187:drug effects; D055590:Electromagnetic Phenomena; D004576:Electromyography; D004832:Epilepsy, Absence / Q000175:diagnosis / Q000503:physiopathology*; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology* / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000502:physiology
D000927:Anticonvulsants