EPC Performance Investigation for StereoElectroEncephaloGraphy

Inclusion Criteria: * To be included, patients must be: * 18 months to 65 years * Patient with drug-resistant and disabling focal epilepsy * Informed and willing to sign an informed consent form approved by EC / For minors: if one of the parents cannot consent within the timeframe provided by the protocol, then only one parent's signature is required * Affiliation to the social security or foreign regime recognized in France * For prospective inclusion: Patient considered for SEEG exploration as part of pre-surgical assessment of epilepsy * For ambispective inclusion: * Must have undergone an SEEG exploration with one ALCIS device before the date of the initiation visit * Follow-up visits (at least 12-month) must be prospective * Must have complete information available for each completed visit (demographics, preoperative information, implantation information, device details) \*. Exclusion Criteria: * • Not able to comply with the study procedures based on the judgment of the assessor (e.g. cannot comprehend study questions, inability to keep scheduled assessment times) * Any medical condition that could impact the study at investigator's discretion (e.g. allergy…) * Pregnant women (contraindication to SEEG exploration) * Adult subject to legal protection measure * Skull thickness inferior at 2 mm