Occipital Nerve Stimulation (ONS) for Migraine: OPTIMISE

Key Inclusion Criteria: * Onset of chronic migraine at least 6 months prior to start of Screening determined by a well-documented history * Evidence of intractability * Posterior-dominant head pain * Stable pattern of headache symptoms for at least 6 months prior to the beginning of Screening * Onset of migraine before the age of 50 * If female of childbearing potential: not pregnant, as evidenced by a negative pregnancy test Key Exclusion Criteria: * Diagnosed with any major psychiatric disorder not specifically listed in Key Exclusion Criteria 2-4 (e.g. multiple personality disorder, schizophrenia) * Untreated panic disorder * Untreated major depression evidenced by a PHQ-9 score \>20 * Untreated generalized anxiety disorder evidenced by a GAD-7 score ≥15 * Currently diagnosed with severe personality disorder * A female of childbearing potential planning to get pregnant during the course of the study or not using adequate contraception * Participating in another drug, device, or biologics trial within 3 months prior to Screening * A terminal illness associated with survival \<24 months