Occipital Nerve Stimulation in Chronic Migraine

Inclusion Criteria: Age ≥ 18 years old and diagnosed with intractable chronic migraine by a headache specialist, as defined by the International Classification of Headache Disorders-3 (ICHD-3). Subject should have failed to gain benefit from at least 4 classes of oral preventative medications, Botulinum toxin or acupuncture as defined by NHS (National Health Service) England Subject has been diagnosed at least 6 months prior to study enrolment with migraine headache with or without aura according to the ICHD-3 criteria 1.1, 1.2.1, or 1.3. Subject is able to distinguish migraine attacks from other headaches (e.g. tension type headache, cluster headaches). Subject agrees to not participate in supplemental or alternative therapy through the Follow Up Period of the study. This includes acupuncture, spinal manipulation, TENS (transcutaneous electrical nerve stimulation), and magnetic fields treatments. Subject has the ability to read, comprehend, and to reliably record information as required by the Protocol. Subject is able to provide written informed consent prior to participation in the study. Exclusion Criteria: Subject's overall health, age and/or comorbidities place subject at high risk for complications from surgery and/or general anaesthesia. Subject has clinically significant drug (including opioid) or alcohol abuse as defined by DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision), will likely be unable to refrain from substance abuse throughout the study, has another significant pain problem, substance abuse or active depressive episode that might confound the study assessments in the opinion of the Investigator. Subject is currently participating or has participated in the last month in another clinical study in which the subject has, is, or will be exposed to, an investigational drug or device, except for sponsor-related studies. Subject is felt to be at risk of non-compliance (e.g., for completing the diary/questionnaires or returning for required follow-up visits) in the Investigator's opinion. Subject has medication overuse headache which has not been managed (by withdrawal of the causative medication). Subject is a woman of childbearing potential who is pregnant, nursing, or not using effective contraception. Subject has an active implantable device such as pacemaker/ defibrillator or other neurostimulation device. Subject has a history of bleeding disorders or coagulopathy or is unable to discontinue…