The main objective of the study is twofold:

1. Assess the clinical efficacy of DBS on epilepsy according to their number and severity at 1 year follow up.
2. Perform a cost-effectiveness analysis from the perspective of Medicare at 1 and 2 years.

The study hypothesis is that thalamic DBS (neurostimulation of the anterior nucleus of the thalamus) will decrease significantly, the frequency (potentially 50% reduction in severe crises) of the most severe seizures, in at least 50% of patients who have drug-resistant partial epilepsy; and should also improve significantly the quality of life through a gain of independence in activities of daily life, the possible recovery of functional abilities, recovery of social or professional activities.

Inclusion Criteria:

• Patient with focal or multifocal epilepsy with or without secondary generalized seizure inoperable at the time of inclusion
• Failure of pharmacological therapies (pharmacoresistant epilepsy) for over 4 years (persistent seizures despite at least two anti-epileptic treatments used at the optimal dose for at least 2 years)
• Failure of vagus nerve stimulation, defined as the persistence of crises considered debilitating after 2 years of VNS's treatment
• VNS failure in a patient treated with VNS, for less than 2 years. with stop early due to the worsening crisis
• Intelligence quotient above 55
• Have the written consent of the legal representative for patients under guardianship and minors
• Affiliation to the french social security system or equivalent
• People who signed the consent form
• Seizure frequency at least 4 crisis / month on average for at least 3 months, about 12 crisis in 3 months objectified by the neurologist during visit pre-inclusion, and confirmed by the neurologist after 3 months of Baseline during the inclusion visit

Exclusion Criteria:

• Patient with a generalized epilepsy Immediately
• Patient with a simple partial seizures (subjective manifestations only)
• Patient with a cons-indication for MRI, a serious intercurrent disease, a progressive brain tumor
• Patient with a suicide risk of in the six months preceding the inclusion visit (score ≥ 2 on item 10 of the Montgomery-Asberg Depression Rating Scale)
• Patient a surgical or anesthetic cons-indication
• Patient with anticoagulant or antiplatelet treatment in the long term
• Woman of childbearing potential without effective contraception, or pregnant or lactating
• People hospitalized without consent
• People deprived of freedom
• Patient currently participating in another clinical research, or who participated in a clinical study in the month preceding the pre-inclusion visit (except for any non-interventional research)