Inclusion Criteria:  Age 18 years and above Signed informed written consent Diagnosed with chronic CH according to the ICHD-3 criteria 15 or more CH attacks per month Stable use of preventive headache medication one month prior to enrollment  Exclusion Criteria:  Other ongoing neuromodulation therapy Current alcohol and/or drug abuse Severe psychiatric disorder Other chronic primary or chronic secondary headache disorder (e.g. chronic migraine) Major posterior neck surgery in C2-C3 level and above Pregnancy Treatment with oral steroids or GON injection within one month of study participation