title: Reduced cranial parasympathetic tone during the remission phase of cluster headache.
abstract: BACKGROUND
  Cluster headache (CH) attacks are accompanied by cranial autonomic symptoms indicative of parasympathetic hyperactivity and sympathetic dysfunction ipsilateral to the pain. We aimed to assess cranial autonomic function in CH patients during the remission phase of cluster headache.
  
  
  METHODS
  During a remission phase, 38 episodic CH patients underwent the following: dynamic pupillometry, measurement of the superficial temporal artery diameter by ultrasound, and measurement of the retinal vessel diameters from digital retinal photographs. Pupillometry was also performed on 30 age- and sex-matched healthy controls.
  
  
  RESULTS
  Thirty patients were included (27 men, three women, mean age 50.2 years ± 12.6). Seven patients reported occasional side shift of their headache, but with a clear predominating side. Significantly reduced average pupillary constriction velocity and retinal venular diameter on the CH pain side were found. There was no asymmetry of the superficial temporal artery diameters. Compared to healthy controls, cluster patients displayed bilaterally reduced pupillary average and maximum constriction velocities, reduced constriction in percentage and increased latency of the light reflex.
  
  
  CONCLUSIONS
  The present findings indicate a bilaterally reduced cranial parasympathetic tone in CH patients in remission phase, with significant lateralization to the CH pain side. This implies a central origin, and a central pathophysiological model of CH is discussed.
authors.affiliation: Nordland Hospital Trust, Norway hkofte@gmail.com.
authors.forename: Hilde K
authors.initials: HK
authors.lastname: Ofte
authors.affiliation: Nordland Hospital Trust, Norway Institute of Clinical Medicine, UiT the Arctic University of Norway, Norway.
authors.forename: Therese
authors.initials: T
authors.lastname: von Hanno
authors.affiliation: Nordland Hospital Trust, Norway Institute of Clinical Medicine, UiT the Arctic University of Norway, Norway.
authors.forename: Karl B
authors.initials: KB
authors.lastname: Alstadhaug
mesh_terms: D003027:Cluster Headache / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology*; D012075:Remission, Spontaneous; D012886:Skull / Q000098:blood supply / Q000503:physiopathology; D013699:Temporal Arteries / Q000503:physiopathology
keywords: Cluster headache; autonomic function; locus coeruleus; paraventricular nucleus of the hypothalamus; pupillometry; retinal vascular caliber