Introduction
CHRONIC CLUSTER HEADACHE, CLUSTER HEADACHE
Medically intractable chronic cluster headache (MICCH) is the most extreme and disabling form of cluster headache, in which patients continue to have frequent, often daily, attacks despite a variety of standard prophylactic medication.We showed in the randomized double-blind ICON study that both 100% and 30% electrical dose occipital nerve stimulation (ONS) were safe, well tolerated and reduced attack frequency by an average of 50% in people with MICCH for at least 48 weeks.Previous retrospectiveIn this structured follow-up study, we prospectively and in detail evaluated the long-term effectiveness and safety of ONS for at least two years in 88 Dutch participants of the ICON trial (L-ICON). Most participants could be followed for much longer, some even for more than eight years. In particular, we evaluated: (i) whether responders remained responders over time; (ii) whether satisfied participants remained satisfied; and (iii) whether non-responders and/or dissatisfied participants could still become responder and/or satisfied.