title: Invasive occipital nerve stimulation for refractory chronic cluster headache: what evolution at long-term? Strengths and weaknesses of the method.
abstract: BACKGROUND
  Invasive Occipital Nerve Stimulation (iONS) is a costly technique which appears effective in drug-refractory chronic cluster headache (drCCH) management. Available data on long-term effectiveness and safety of iONS in this indication are scarce, though they could be useful to neurologists and patients in daily practice. The purpose of this short report is to discuss the very long-term outcome of a drCCH cohort, including adverse events.
  
  
  RESULTS
  Previously, favourable results were obtained with iONS in 15 drCCH patients: 80 % were significantly improved and 60 % were pain free. We report here the very long-term follow-up (up to nine years) of 10 patients belonging to this cohort. Meanwhile 5 patients had to be definitively explanted because of device infection (3) or paresthesia intolerance (2). Four patients (40 %) evolved to an episodic form of CH. Six remained chronic but their attack frequency was decreased by 70 % on average. Intake of preventive drugs is still necessary in 80 % of patients. All patients needed at least one battery replacement.
  
  
  CONCLUSIONS
  Up to nine years after implantation, iONS is still effective in most patients with drCCH. Concomitant preventive drugs remain often necessary. Forty percent of patients reverse to episodic CH, possibly by natural history. iONS is not a benign procedure but device-related complications appear similar to those reported with other invasive neurostimulators.
authors.affiliation: Headache Research Unit, University Department of Neurology CHR, Boulevard du 12ème de Ligne 1, 4000, Liège, Belgium. dmagis@chu.ulg.ac.be.
authors.forename: Delphine
authors.initials: D
authors.lastname: Magis
authors.affiliation: Headache Research Unit, University Department of Neurology CHR, Boulevard du 12ème de Ligne 1, 4000, Liège, Belgium.
authors.forename: Pascale
authors.initials: P
authors.lastname: Gérard
authors.affiliation: Headache Research Unit, University Department of Neurology CHR, Boulevard du 12ème de Ligne 1, 4000, Liège, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Schoenen
mesh_terms: D000328:Adult; D002572:Cervical Plexus / Q000502:physiology*; D003027:Cluster Headache / Q000209:etiology / Q000628:therapy*; D004599:Electric Stimulation Therapy / Q000009:adverse effects / Q000379:methods*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care
keywords: Adverse events; Cluster headache; Neurostimulation; Occipital nerve; Refractory