Epilepsia partialis continua. Epileptogenic focus in motor cortex and its participation in transcortical reflexes.

We performed electrophysiologic and neuroradiologic studies on a patient who had epilepsia partialis continua (EPC) to elucidate the pathophysiologic mechanism of repeated myoclonic jerks confined to the right toes. A computed tomographic scan revealed a small cortical lesion in the left parasagittal rolandic area corresponding to the sensorimotor cortex of the right toes. A pretrigger EEG analysis with a jerk-locked averaging technique revealed a positive spike 32 ms before the jerks. A similar positive spike was evoked at a latency of 48 ms after an electrical stimulation of the right posterior tibial nerve; it was followed by a myoclonic jerk with a 32-ms latency. We suppose that in our patient, an epileptogenic focus in the motor cortex and transcortical long-loop reflexes played an important role in generating EPC.