Chronic Cluster Headache

This is a limited open-label study being performed at two centers in the Netherlands. All participants will receive the same treatment, and both the patients and doctors will know what that treatment is. The goal is to see how safe and effective the PRIMUS system is for preventing Chronic Cluster Headaches (CCH) in people who haven't responded well to the drug verapamil. The study will also look at the patients' experience using the system.

The purpose of this clinical trial is to evaluate the safety and effectiveness of the Occipital Nerve Stimulation System (ONSS) in treating chronic cluster headache in adults. The study aims to answer the following questions: * What adverse events or medical complications occur following ONSS implantation and stimulation? * Does treatment with the ONSS reduce the frequency of cluster headache attacks compared with baseline? Participant Involvement Participants will: * Undergo implantation of the ONSS device. * Use the ONSS for a 48-week treatment period. * Attend scheduled clinic visits for follow-up assessments and device evaluations. * Maintain a diary documenting cluster headache attacks and use of rescue medications. * Complete study-related assessments throughout the study period.

The goal of this clinical trial is to evaluate the efficacy of low sodium oxybate (LXB) (brand name Xywav) in the treatment of (nocturnal) cluster headache attacks in subjects with chronic cluster headache. It is an 16 week, randomized, double-blind, placebo- controlled, bi-center trial. LXB will be administered as a twice nightly regimen. All subjects will undergo an 6 week Treatment Titration and Optimization Phase. The main trial endpoint is the change from baseline in average weekly frequency of nocturnal cluster headache attacks over 4-week fixed stable dose of treatment period.

This study aims to investigate the efficacy and safety of LSD 25μg every 3 days for 3 weeks versus placebo in the treatment of chronic cluster headache (cCH). It is a 3-week double-blind placebo-controlled intervention study, preceded by a 4-week baseline observation period and followed by a 5-week post-treatment observation period. Primary objective: to evaluate the efficacy of LSD 25μg every 3 days for 3 weeks in cCH. Additional objectives: * To evaluate the safety of LSD 25μg every 3 days for 3 weeks in cCH. * To explore the exposure-response relationship of 25μg LSD in cCH. * To explore cost-effectiveness of treatment with LSD in cCH. * To evaluate the efficacy of LSD on health-related quality of life.