Cortical excitability predicts seizures in acutely drug-reduced temporal lobe epilepsy patients.
OBJECTIVE
To test the hypothesis that cortical excitability changes prior to seizures, using transcranial magnetic brain stimulation (TMS).


METHODS
We studied 18 patients with unilateral temporal lobe epilepsy (TLE) twice using TMS: prior to (day 1) and following (day 3) reduction of antiepileptic drugs in a monitored inpatient setting. Short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF) were measured. Time since most recent seizure prior to day 1, and time until next seizure after day 3, were recorded.


RESULTS
On day 1, prior to antiepileptic drug withdrawal, there were no correlations with recent or next seizures. On day 3, patients who had seizures in the subsequent 48 hours had weaker SICI and ICF in the hemisphere ipsilateral to seizure onset, vs patients who did not have seizures in the next 48 hours (p = 0.033). Additionally on day 3, there was a strong correlation between the difference between ICF and SICI in the ipsilateral hemisphere and time to next seizure (p < 0.001).


CONCLUSIONS
Change in cortical excitability, measured with transcranial magnetic brain stimulation, may reflect a long-lasting and widespread pre-ictal state.
Wright
M-A S Y
MA
Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, UK.
Orth
M
M
Patsalos
P N
PN
Smith
S J M
SJ
Richardson
M P
MP
D000208:Acute Disease / Q000628:therapy; D000328:Adult; D000927:Anticonvulsants / Q000008:administration & dosage / Q000009:adverse effects*; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D004569:Electroencephalography / Q000592:standards; D004576:Electromyography; D004827:Epilepsy / Q000139:chemically induced / Q000175:diagnosis* / Q000503:physiopathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D011237:Predictive Value of Tests; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation / Q000379:methods* / Q000592:standards
D000927:Anticonvulsants