REsponse to Combined SONS and ONS in Chronic Cluster headachE

Main Inclusion Criteria: * Able and willing to provide informed consent * Documented chronic cluster headache for at least 1 year as per ICHD-3 criteria * Attack frequency of ≥ 4 attacks per week for ≥ 4 weeks before enrolment * Documented failure of verapamil (failure meaning ineffective, provoked unacceptable side-effects or contra-indicated) * Stable on preventive treatment for at least two weeks prior to enrolment. * Agree to refrain from starting new prophylactic cluster headache medication or other preventive treatments, from 4 weeks before entering the baseline period throughout the duration of the study * MRI available (not older than 4 years prior to study enrolment) or willing to undergo an MRI to exclude structural lesions potentially causing headache * Able and willing to complete a headache Diary Main Exclusion Criteria: * Any other chronic primary or secondary headache disorder, unless they can clearly differentiate them from cluster headache attacks based on the quality and associated symptoms * Concomitant neuromodulation, except tVNS * Previous failure to any implantable neuromodulation device for neurovascular headache * Have an existing Active Implantable Medical Device nearby the implant location (e.g. DBS, cochlear implant, …) * Metal implants in the skull (e.g. skull plates, seeds) nearby the implant * Have a pacemaker or implantable cardioverter defibrillator (ICD) * Suboccipital infiltrations with steroids and/or local anaesthetics or use of oral steroids in the past 3 months * Use of botulinum toxin injections in the past 12 weeks * Calcitonin gene-related peptide inhibitors started less than 12 weeks prior to enrolment * Women of childbearing age who are pregnant, nursing or not using contraception