Quantitative analysis of intracerebral recordings in epilepsia partialis continua

A 14-year-old female with epilepsia partialis continua was explored stereo-electroencephalographically (SEEG). SEEG, EEG and EMG were recorded synchronously on a 32-channel machine and stored on magnetic tape for off-line analysis. The beginning of the myoclonus was used as trigger for the analysis of the intracerebral activity, which was analysed by averaging. Thereby the generating potentials of the jerks became evident. They had different maxima and latencies relative to the facial and hand muscles: that for m. orbicularis oculi was located in the precentral gyrus, the beginning of its positive deflection was 17 msec earlier than the muscle action potential; that for the thenar muscles had a latency of 24 msec, appeared at first in the premotor cortex and with a slight delay, but with greater amplitude in the corona radiata and capsula interna. Stimulation of the lateral area 4 elicited myoclonus which corresponded to the spontaneous one in distribution and latency. Stimulation of the thalamic VL nucleus had no effect. During deep sleep the frequency of the myoclonus was diminished. REM sleep was preceded and followed by a definite increase of jerking. The pattern, topography and latency of the generating potentials in waking and sleeping were very similar. In this way quantitative evidence of the neocortical origin of Epc is given and therefore a precise delineation of the epileptogenic focus.