Contribution of motor cortex in generation of evoked spikes in patients with benign rolandic epilepsy

Objectives. Among the different kinds of rolandic epilepsy there is a form of benign epilepsy with centrotemporal spikes (BECT) presenting the peculia r characteristic of evoking rolandic paroxysmal activity, characterized by a spike followed by a slow wave, using electrical stimulation of the finger s. Methods: We evaluated 7 patients suffering from BECT presenting evoked scal p activity by electrical stimulation of the fingers of the hand. Electrical stimulation was performed using a pair of ring electrodes applied to the t humb. The motor evoked potentials (MEPs) were elicited in hand muscles by t ranscranial magnetic stimulation (TMS) and were conditioned by the same ele ctrical digital stimulation producing the evoked spikes at interstimulus in tervals ranging from 10 to 200 ms. Results: Digital stimulation in epileptic patients produced an increase in MEP amplitude substantially above the normal ranges, MEP facilitation showe d a time course overlapping the ascending phase and peak of the evoked spik e, whereas no significant MEP changes were found during the early positive peak and the descending phase of the spike, or during the following slow wa ve. Conclusions: Several considerations support the hypothesis that the short-l asting M1 facilitation is related to the spread of an abnormal hypersynchro nous discharge of the S1 neurones to functionally related motor areas via c ortico-cortical connections. (C) 2000 Elsevier Science Ireland Ltd. All rig hts reserved.