[Neurophysiological aspects of multiple hippocampal transection in intractable temporal lobe epilepsy]

To search for correlations between intraoperative electrocorticographic data and seizure control after the multiple hippocampal transections (MHT) in patients with symptomatic pharmacoresistant medial temporal lobe epilepsy.

Six patients underwent MHT nearby the hippocampus. The left dominant hemisphere was affected in all cases. Patients had normal memory function. Follow up was 18 to 24 months. Scalp electroencephalogram (EEG) and electrocorticography (ECoG) were intaoperatively recorded. Transections of the hippocampus were performed until ECoG epileptiform discharges stopped.

Seizure control was achieved in five patients. Synchronous epileptiform activity disappeared in the hippocampus in all patients after MHT. Complete disappearance of epileptiform activity in the hippocampus and basal cortex was demonstrated in 2 cases. The epileptiform activity remained in the basal cortex in 3 patients.

Using the method of hippocampal transections it was possible to achieve the disappearance of synchronous epileptic activity in the hippocampus in all patients. It is correlated with good outcome in 5 out of 6 cases. Preservation and even arising of spiking in the basal temporal cortex are not a risk factor for maintaining seizures after complete resection of the epileptogenic substrate in the temporal lobe and hippocampal transections. A decrease in the background epileptiform activity on the scalp EEG was observed in 4 of 5 cases after the resection of the pathological substrate, uncus and amygdala.