title: Orthostatic instability in a population-based study of chronic fatigue syndrome.
abstract: OBJECTIVE
  Autonomic nervous system dysfunction has been suggested as involved in the pathophysiology of chronic fatigue syndrome. This population-based case control study addressed the potential association between orthostatic instability (one sign of dysautonomia) and chronic fatigue syndrome.
  
  
  METHODS
  Fifty-eight subjects who fulfilled criteria of the 1994 chronic fatigue syndrome research case definition and 55 healthy controls participated in a 2-day inpatient evaluation. Subjects had been identified during a 4-year population-based chronic fatigue syndrome surveillance study in Wichita, Kan. The present study evaluated subjects' current medical and psychiatric status, reviewed past medical/psychiatric history and medication use, used a stand-up test to screen for orthostatic instability, and conducted a head-up tilt table test to diagnose orthostatic instability.
  
  
  RESULTS
  No one manifested orthostatic instability in the stand-up test. The head-up tilt test elicited orthostatic instability in 30% of eligible chronic fatigue syndrome subjects (all with postural orthostatic tachycardia) and 48% of controls (50% with neurally mediated hypotension); intolerance was present in only nonfatigued (n=7) subjects. Neither fatigue nor illness severity were associated with outcome.
  
  
  CONCLUSIONS
  Orthostatic instability was similar in persons with chronic fatigue syndrome and nonfatigued controls subjects recruited from the general Wichita population. Delayed responses to head-up tilt tests were common and may reflect hydration status. These findings suggest reappraisal of primary dysautonomia as a factor in the pathogenesis of chronic fatigue syndrome.
authors.affiliation: Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Ga 30333, USA. jaj9@cdc.gov
authors.forename: James F
authors.initials: JF
authors.lastname: Jones
authors.forename: Ainsley
authors.initials: A
authors.lastname: Nicholson
authors.forename: Rosane
authors.initials: R
authors.lastname: Nisenbaum
authors.forename: Dimitris A
authors.initials: DA
authors.lastname: Papanicolaou
authors.forename: Laura
authors.initials: L
authors.lastname: Solomon
authors.forename: Roumiana
authors.initials: R
authors.lastname: Boneva
authors.forename: Christine
authors.initials: C
authors.lastname: Heim
authors.forename: William C
authors.initials: WC
authors.lastname: Reeves
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000209:etiology* / Q000503:physiopathology; D016022:Case-Control Studies; D015673:Fatigue Syndrome, Chronic / Q000150:complications* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007024:Hypotension, Orthostatic / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D013610:Tachycardia / Q000209:etiology / Q000503:physiopathology; D018667:Tilt-Table Test