title: Cardiovascular response to upright tilt in fibromyalgia differs from that in chronic fatigue syndrome.
abstract: OBJECTIVE
  To compare the cardiovascular response during postural challenge of patients with fibromyalgia (FM) to those with chronic fatigue syndrome (CFS).
  
  
  METHODS
  Age and sex matched patients were studied, 38 with FM, 30 with CFS, and 37 healthy subjects. Blood pressure (BP) and heart rate (HR) were recorded during 10 min of recumbence and 30 min of head-up tilt. Differences between successive BP values and the last recumbent BP, their average, and standard deviation (SD) were calculated. Time curves of BP differences were analyzed by computer and their outline ratios (OR) and fractal dimensions (FD) were measured. HR differences were determined similarly. Based on the latter measurements, each subject's discriminant score (DS) was computed.
  
  
  RESULTS
  For patients and controls average DS values were: FM: -3.68 (SD 2.7), CFS: 3.72 (SD 5.02), and healthy controls: -4.62 (SD 2.24). DS values differed significantly between FM and CFS (p < 0.0001). Subgroups of FM patients with and without fatigue had comparable DS values.
  
  
  CONCLUSIONS
  The DS confers numerical expression to the cardiovascular response during postural challenge. DS values in FM were significantly different from DS in CFS, suggesting that homeostatic responses in FM and CFS are dissimilar. This observation challenges the hypothesis that FM and CFS share a common derangement of the stress-response system.
authors.affiliation: Departments of Internal Medicine A, Rheumatology, Anesthesiology, and Surgery, Bnai Zion Medical Center and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: J E
authors.initials: JE
authors.lastname: Naschitz
authors.forename: M
authors.initials: M
authors.lastname: Rozenbaum
authors.forename: I
authors.initials: I
authors.lastname: Rosner
authors.forename: E
authors.initials: E
authors.lastname: Sabo
authors.forename: R M
authors.initials: RM
authors.lastname: Priselac
authors.forename: N
authors.initials: N
authors.lastname: Shaviv
authors.forename: A
authors.initials: A
authors.lastname: Ahdoot
authors.forename: M
authors.initials: M
authors.lastname: Ahdoot
authors.forename: L
authors.initials: L
authors.lastname: Gaitini
authors.forename: S
authors.initials: S
authors.lastname: Eldar
authors.forename: D
authors.initials: D
authors.lastname: Yeshurun
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005356:Fibromyalgia / Q000175:diagnosis / Q000503:physiopathology*; D017709:Fractals; D006339:Heart Rate; D006801:Humans; D008297:Male; D011187:Posture; D018667:Tilt-Table Test