title: Sustained effectiveness of occipital nerve stimulation in drug-resistant chronic cluster headache.
abstract: BACKGROUND
  Drug-resistant chronic cluster headache (drCCH) is a devastating condition for which various invasive therapeutic procedures have been tempted without any satisfactory effect. Recent studies suggest that occipital nerve stimulation (ONS) could be an efficient preventive treatment of drCCH.
  
  
  OBJECTIVE
  We conducted a prospective pilot trial of ONS in 8 subjects suffering from drCCH with encouraging results at 15 months. However, studies on a larger population with a longest follow-up were warranted.
  
  
  METHODS
  We recruited 15 patients with drCCH according to the previously published criteria of intractability. They were implanted with suboccipital stimulators on the side of their headache. Long-term follow-up was achieved by questionnaires administered during a headache consultation and/or by phone interviews.
  
  
  RESULTS
  Mean follow-up time post surgery is 36.82 months (range 11-64 months). One patient had an immediate post-operative infection of the material. Among the 14 remaining patients, 11 (i.e., ∼80%) have at least a 90% improvement with 60% becoming pain-free for prolonged periods. Two patients did not respond or described mild improvement. Intensity of residual attacks is not modified by ONS. Four patients (29%) were able to reduce their prophylaxis. The major technical problems were battery depletion due to the use of high current intensities (N = 9/14, 64%) and immediate or delayed material infection (N = 3/15, 20%). Significant electrode migration was only seen in 1 patient. Clinical peculiarities during the ONS follow-up period were side shift with infrequent contralateral attacks (N = 5/14, 36%), and/or isolated ipsilateral autonomic attacks without pain (N = 5/14, 36%). Two patients found ONS-related paresthesias unbearable: one had his stimulator removed, and the other switched it off although he was objectively ameliorated. Subjectively, 9 patients are very satisfied by ONS and 3 patients moderately satisfied. Effective stimulation parameters varied between patients.
  
  
  CONCLUSIONS
  Our long-term follow-up confirms the efficacy of ONS in drCCH, which remains a safe and well-tolerated technique. The occurrence of contralateral attacks and isolated autonomic attacks in nearly 50% of ONS responders may have therapeutic and pathophysiological implications.
authors.affiliation: Headache Research Unit, CHR Citadelle, Department of Neurology, University of Liège, Liège, Belgium. dmagis@chu.ulg.ac.be
authors.forename: Delphine
authors.initials: D
authors.lastname: Magis
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Gerardy
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Remacle
authors.forename: Jean
authors.initials: J
authors.lastname: Schoenen
mesh_terms: D000328:Adult; D000368:Aged; D003027:Cluster Headache / Q000628:therapy*; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009802:Oculomotor Nerve / Q000502:physiology*; D010147:Pain Measurement; D010865:Pilot Projects; D013997:Time Factors