Low-frequency electric cortical stimulation decreases interictal and ictal activity in human epilepsy.

We previously reported that low-frequency electric cortical stimulation (LFECS) directly applied to the epileptic focus by means of subdural electrodes decreased the number of interictal epileptiform discharges in patients with intractable partial epilepsy. In the present study, LFECS was applied to the epileptic foci directly in four patients with medically intractable partial epilepsy through subdural electrodes and evaluated its effect on the number of interictal epileptiform discharges as well as simple partial seizures. We used alternating electric current of 0.3 ms duration presented at 0.9 Hz frequency for 250 s. LFECS did not induce seizures in any of the four patients. In one patient, the number of interictal epileptiform discharge decreased significantly by LFECS, which is in conformity with our previous report. In addition, LFECS applied to the seizure onset zone decreased the frequency of simple partial seizures in one patient. These results suggest that LFECS has an inhibitory effect not only on the interictal but also the ictal activities in patients with intractable partial epilepsy. Further study is required to determine the inhibitory effect of LFECS more in details.