EEG CHANGES FOLLOWING REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION INPATIENTS WITH TEMPORAL-LOBE EPILEPSY

Transcranial magnetic stimulation (TMS) has been proposed as an epilep togenic activating procedure in the evaluation of patients with partia l epilepsy. With the introduction of repetitive (rapid rate) transcran ial magnetic stimulation (RTMS), it has been possible to apply cortica l stimuli with a stimulus rate up to 50 Hz. This study was conducted i n order to evaluate the epileptogenic effect of RTMS. Ten patients suf fering from medically intractable temporal robe epilepsy were included . As a part of the presurgical evaluation all patients were studied wi th ictal video-EEG scalp recordings during a period of discontinuation of the antiepileptic treatment. Eight RTMS trains were applied to lef t and right temporal and frontal areas, using a stimulus intensity of 1.2 x Tm (the motor threshold to a twitch in the right hand), a stimul us duration of 1 s and a stimulus frequency of 30 Hz. 50 Hz stimulatio ns, with a stimulus duration of 1 s and a stimulus intensity of 1.2 x Tm, were applied on both anterior temporal regions, in total 10 TMS an d 340 RTMS pulses to each patient. The numbers of sharp waves/spikes a nd low-frequency potentials were lower (P<0.01) compared to prestimulu s values and returned to prestimulation values within 10 min. In no ca ses paroxysmal activity was provoked and no seizures developed. The st udy indicates that RTMS as used in this study is not effective as an a ctivation procedure for paroxysmal activity. As the risk of seizures m ay depend on the stimulus parameters, further studies are needed in or der to evaluate the safety of the RTMS.