Abstracts

Slow rTMS may decrease cortico-spinal excitability, suggesting that this technique might be used to decrease cortical excitability in patients with refractory epilepsy. A few animal and human studies indicate that this technique might be effective in seizure control. However, others have failed to find beneficial effects of rTMS on epileptic activity. Herein, we explore the question of whether rTMS might be clinically useful in patients with malformations of cortical development (MCD) and refractory epilepsy. Patients were prospectively selected if they fulfilled the following criteria: diagnosis of MCD based on MRI; refractory epilepsy; non-surgical and AED compliance. Patients were excluded if they had ferromagnetic metallic implants, history of major head trauma or were unable to cooperate with the procedure. Eight patients (mean age 24.2 [plusmn] 9.5y) participated in the study. [underline]EEG[/underline][italic]: [/italic]All patients underwent EEG before, immediately after, 15 and 30 days following rTMS. The number of epileptiform discharges (ED) on EEG was counted in two epochs of 5 minutes. [underline]Clinical Outcome[/underline][italic]: [/italic]Subjects recorded number of seizures in a calendar in the month before and two months after rTMS treatment. In order to minimize placebo effect all patients were told that the primary aim of the study was to investigate the effects of rTMS on EEG. [underline]TMS[/underline]: The site for stimulation was determined according to EEG 10-20 system. We targeted the foci in patients with focal ED and Pz in patients with multifocal or diffuse ED and lesions. In one of the patients with bilateral lesions and ED, we stimulated two areas that seemed to be equally active on EEG. Stimulation parameters were frequency of 0.5Hz and intensity of 65% of maximum output stimulator intensity in one session of 20 minutes (600 pulses). [underline]EEG[/underline]: rTMS significantly decreased the number of ED immediately after rTMS by 30% compared to baseline (p=0.011). The comparison between the baseline EEG and the EEGs performed 15 and 30 days after the treatment showed an average reduction of 52% and 46%, respectively, in the number of ED (p=0.016 and p=0.017). [underline]Clinical Outcome[/underline]: rTMS markedly reduced the number of seizures in 7 patients. After 15 and 30 days of the stimulation, the patients reported a significant reduction in the number of seizures, showing a decrease of 53% and 47%, respectively (p=0.018 and p=0.027). Only one patient with periventricular nodular heterotopia had no alteration in frequency of seizures and EEG showed an increase in the number of ED after 15 and 30 days of treatment. No seizures were induced by low frequency rTMS in any of these patients. In this study, clinical and neurophysiological outcome corroborates the evidence obtained with animal models, decreasing cortical excitability, even in lesions with a high epileptogenicity such as MCD.