A First-in-human Study to Assess the Initial Safety, Tolerability, and Effectiveness of the ONSS Bilateral Occipital Nerve Field Stimulation System for the Prophylactic Treatment of Chronic Cluster Headache in Difficult-to-treat Subjects.

Exclusion criteria

• . Other significant neurological, psychiatric, or disabling diseases which in the opinion of the investigator may interfere with the study.
• . History of epilepsy, current treatment of epilepsy
• . Documented history of cerebrovascular accident (CVA)
• . Participants suffering from a substance use disorder, as defined by Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria. Recreational use of cannabis is allowed.
• . Participants at high risk of suicide/suicidal ideation in the past one year assessed with the C-SSRS at screening
• . Having another active implanted device such as a cardiac pacemaker, a spinal cord, peripheral nerve, sphenopalatine ganglion, or deep brain hypothalamic stimulator, and/or a drug delivery pump, etc.
• . Cranial botulinum toxin injections in the past 3 months before enrolment. Administration of the following treatments in the last month before enrolment: monoclonal antibodies blocking calcitonin gene-related peptide transmission, suboccipital infiltrations with steroids and/or local anesthetics, oral steroids, radiofrequency procedure or infiltrations of the sphenopalatine ganglion, opioids WHO 3. Oral or systemic steroids are not allowed during the month before enrolment, except low doses (prednisone not superior to 10mg/day for no more than 7 days) if needed for other disorders.
• . Medication overuse headache (ICHD 3 8.2)