When focal epilepsies become drug-resistant, it could be eligible for cortical surgical resection. Therefore, an invasive EEG monitoring with depth electrodes is often needed during presurgical evaluation. Some of these children can have access to thermocoagulation inside the ictal onset zone, at the end of the monitoring and before to remove the electrodes. These thermocoagulations can disorganize the epileptogenic network thanks to millimetric cortical lesions around the electrodes. The aim is to stop or at least, to reduce the seizure frequency for few weeks or months. This could be a benefit for the child, and also a confirmation of the ictal onset zone and guide the surgeon. This technique is currently used in adult population for years, but remains very rare in children.

Inclusion Criteria:

• age 18 month to 17 years old
• focal drug-resistant epilepsy
• small size lesion (1 or 2 gyri) or cryptogenic epilepsy
• indication for EEG monitoring with depth electrodes during presurgical evaluation

Exclusion Criteria:

• formal contraindication to surgery or anaesthesia
• functional area or potentially large epileptic area
• refusal to participate in the study
• no health insurance coverage