title: An exploratory study of salivary calcitonin gene-related peptide levels relative to acute interventions and preventative treatment with onabotulinumtoxinA in chronic migraine.
abstract: OBJECTIVE
  To determine if baseline/interictal saliva calcitonin gene-related peptide (CGRP) levels would be lower in subjects with chronic migraine receiving onabotulinumtoxinA compared with those receiving saline.
  
  
  BACKGROUND
  CGRP is considered central to the pathogenesis of episodic migraine, but its relationship to chronic migraine is less understood. OnabotulinumtoxinA is an effective treatment for chronic migraine and has been demonstrated to inhibit the vesicular release of CGRP.
  
  
  METHODS
  This was an exploratory, randomized, placebo-controlled, crossover pilot study of 20 subjects that received onabotulinumtoxinA and saline injection (placebo). The amount of CGRP in saliva samples collected on a nonheadache or low headache day, and prior to and after treatment of a headache exacerbation was measured. Daily headache records, medications, and response to treatment were recorded in a diary.
  
  
  RESULTS
  A decrease in baseline/interictal saliva CGRP levels for subjects receiving onabotulinumtoxinA from 39.4 ± 7.5 pg CGRP/mg total protein after the first month to 25.5 ± 4.1 pg after the third month was observed. However, this difference did not reach significance nor was it significant when compared to the saline treatment. There was a reduction in the number of headache days for both onabotulinumtoxinA and saline over baseline throughout the active phases of the study. However, there was no statistical difference in headache days between groups. Subjects with a greater than 50% response to onabotulinumtoxinA had better 2-hour pain relief with acute treatment than non-responders to onabotulinumtoxinA or saline.
  
  
  CONCLUSIONS
  While CGRP levels were not elevated during a migraine attack in chronic migraine subjects as has been reported in episodic migraine, there was an overall decrease in the baseline/interictal levels in response to onabotulinumtoxinA.
authors.affiliation: Headache Care Center, Springfield, MO, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Cady
authors.forename: Ira
authors.initials: I
authors.lastname: Turner
authors.forename: Kent
authors.initials: K
authors.lastname: Dexter
authors.forename: M E
authors.initials: ME
authors.lastname: Beach
authors.forename: Ryan
authors.initials: R
authors.lastname: Cady
authors.forename: Paul
authors.initials: P
authors.lastname: Durham
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002908:Chronic Disease; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000188:drug therapy* / Q000378:metabolism / Q000517:prevention & control*; D010147:Pain Measurement; D010865:Pilot Projects; D012463:Saliva / Q000378:metabolism*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D019274:Botulinum Toxins, Type A; D015740:Calcitonin Gene-Related Peptide
keywords: acute treatment; calcitonin gene-related peptide; chronic migraine; episodic migraine; onabotulinumtoxinA; pathophysiology