Inclusion Criteria:
1. Ability to understand the Informed Consent Form (ICF) and the study procedures and provide written consent or, in case of cognitive impairment, be the legal ward of a person who is able and willing to provide written consent.
2. Subjects diagnosed with Drug Resistant Epilepsy (DRE) and candidate for VNS treatment
3. Ability of subjects or, in the case of cognitive impairment, their caregiver, to accurately count seizures and complete seizure diaries.
4. Adult subjects, age ≥ 18.
5. Willingness of subjects or, in the case of cognitive impairment, their caregiver, to charge the NAO.VNS system with the Smart Charger on a weekly basis.
6. Subjects' willingness to follow the protocol procedures. For example, subject should have a careful seizure diary completion according to standard of care to ensure 8 weeks of data available by time of implant.
7. Female subjects of childbearing age using acceptable methods of birth control (abstinence considered acceptable).
Exclusion Criteria:
1. Unstable medical condition likely to precipitate seizures and make it difficult to evaluate efficacy.
2. Prior cervical vagotomy.
3. Progressive neurological disease.
4. Pregnancy.
5. Significant cardiac or pulmonary disease under treatment.
6. History of noncompliance for seizure diary completion.
7. Prior implant with vagus nerve stimulation device.
8. Current active treatment of epilepsy with cerebellar or thalamic stimulation.
9. Prior therapeutic brain surgery for epilepsy within the last 6 months prior to NAO.VNS implantation.
10. Receiving or likely to receive short-wave diathermy, microwave diathermy, or therapeutic ultrasound diathermy after implantation.
11. Currently receiving another investigational treatment.
12. Patient with Vocal Cord Palsy (VCP), including unilateral, whatever the side.
13. Diabetic patients and all patients with a known vagal neuropathy.
14. Coagulation disorder, wound healing and bleeding disorder or taking anticoagulant medication (oral anticoagulants; antiplatelets (such as aspirin, ticagrelor) are allowed).
15. Patient currently participating in another clinical investigation, without explicit consent of the Sponsor (non-interventional registries are allowed).
