A Multicenter Study of Hippocampal Electrical Stimulation (HS, in Mesial Temporal Lobe Epilepsy

This is a multicentre, parallel-group, double blind randomized controlled trial involving patients with MTLE who may be candidates for resective surgery or whose memory function precludes resective surgery. Eligible patients will be randomized in a 2:1 ratio into hippocampal electrode implantation with stimulation (HS), or hippocampal electrode implantation without stimulation (HI). Patients will be followed for seven months after randomization. One month will be devoted to adjustment of interventions, and 6 months to follow-up and outcome assessment. At the end of seven months, all patients will be offered the option of HS, electrode removal, surgical therapy or medical therapy, based on best evidence and patient preference. Primary Question: In patients with MTLE, over a 6-month period: Is continuous HS plus medical therapy (MT) more efficacious than hippocampal implantation (HI) plus MT in reducing seizure frequency? Secondary Questions: In patients with MTLE, over a 6-month period: 1. Is HS safe? 2. What is the effect of HS on cognition, mood, and quality of life? 3. What is the effect of HS on psychiatric morbidity? 4. Is the efficacy of HS associated with the presence, location and amount of interictal hippocampal spikes on depth electrode recordings?