Epilepsia partialis continua: active cortical spike discharges and high cerebral blood flow in the motor cortex and enhanced transcortical long loop reflex.

We report a patient suffering from persistent myoclonic jerks in the right forearm without any definite EEG abnormality under routine recording conditions. By computer summation, using the jerk-locked averaging technique, a sharp spike was recognized as a precisely time-locked event in relation to myoclonic twitches. A cranial CT scan revealed a small cortical lesion, which was found very close to the sensorimotor cortex of the right arm. Cerebral blood flow study using the xenon inhalation method revealed a discrete focus of high flow, which corresponded well with the CT lesion. On electrical stimulation of the right median nerve, a large somatosensory evoked potential and an enhanced transcortical long loop reflex were observed. Electrocorticogram showed active focal spike discharges localized at the left precentral gyrus. We postulate that an epileptogenic focus in the motor cortex and an enhanced transcortical long loop reflex appear to be important for the occurrence of epilepsia partialis continua in this patient.