Patients will be prospectively randomized to 3 different treatment arms:

• Treatment group 1: patients who undergo medial temporal lobe resection
• Treatment group 2: patients who receive immediate hippocampal neurostimulation
• Treatment group 3: patients who are implanted with an intracranial electrode but in whom hippocampal neurostimulation is delayed for 6 months.

Twelve months after inclusion unblinding will occur. Patients in group 2 and 3 will have the option to choose between continuing neurostimulation treatment or resective surgery.

Study visits will occur every 3 months.

Inclusion Criteria:

• Presurgical candidates with pharmacoresistant partial seizures despite optimal medical treatment and history of temporal lobe epilepsy
• Age above 18 years
• TIQ > 80
• Able to give informed consent
• Average of 2 partial seizures per month during a baseline of 3 months. Recording of seizures must have been done in a prospective manner using standard seizure diaries.
• Able to adequately report seizure frequencies using standard seizure diaries
• Video-EEG characteristics showing temporal lobe seizure onset (left-sided or right-sided seizure onset) in at least one recorded habitual seizure
• Presence of a structural abnormality in the medial temporal lobe, suggestive of hippocampal sclerosis as evidenced by optimum MRI
• Women of child-bearing age will be required to use a reliable method of contraception during the study duration

Exclusion Criteria:

• Extratemporal epilepsy; multifocal epilepsy; evidence of bilateral medial temporal lobe epilepsy
• MR evidence of potentially epileptogenic lesions outside the medial temporal lobe such as dysplasias, tumours or cavernomas
• Prior resective intracranial surgery
• Patients who are candidates for invasive video-EEG recording or have previously been investigated with invasive video-EEG recording
• Patients who previously underwent any other type of neurostimulation for treating epilepsy
• Patients who are unable to fill in questionnaires and comply with protocol requirements
• Progressive neurological or medical conditions
• Medical or psychiatric conditions precluding surgery or compliance
• Patients taking antidepressant medication
• Pregnancy at study onset
• Previous (within the last 3 months), ongoing or planned participation in other treatment study protocols for epilepsy
• Contraindication for intracranial surgery