title: Heart rate variability in sciatica patients referred to spine surgery: a case control study.
abstract: BACKGROUND
  A chronic pain condition may result in altered autonomic nervous system regulation in various patient populations. We evaluated whether autonomic regulation differs between sciatica patients referred to spine surgery and age-matched healthy controls analyzed with heart rate variability techniques (HRV).
  
  
  METHODS
  HRV of patients (n = 201) and healthy controls (n = 138) were measured in standing conditions (5 min). High frequency (HF) power as an index of cardiac vagal modulation and the low-to-high-frequency (LF/HF) ratio and short-term fractal scaling exponent α1 as indices of sympathovagal balance were analyzed. Pain intensity was assessed on a Visual Analog Scale (VAS) and perceived disability with Oswestry Disability Index.
  
  
  RESULTS
  The Oswestry and VAS scores were higher in the patients than in the controls (p < 0.0001 for both). HF power was markedly lower for the patients compared to the controls (p < 0.0001). The LF/HF ratio and α1 were higher in the patients than in the controls (p < 0.01 for both). After adjusting for sex, smoking, BMI, and leisure-time physical activity, HF power (p = 0.011) and α1 (p = 0.012) still differed between the groups. Among the patients, HF power was slightly associated with the duration of chronic pain (r = -.232, p = 0.003).
  
  
  CONCLUSIONS
  Sciatica patients referred to spine surgery had altered cardiac autonomic regulation expressed as decreased vagal activity and an increased sympathovagal balance toward sympathetic dominance when compared with age-matched healthy controls.
authors.forename: Jarmo
authors.initials: J
authors.lastname: Södervall
authors.forename: Jaro
authors.initials: J
authors.lastname: Karppinen
authors.forename: Jukka
authors.initials: J
authors.lastname: Puolitaival
authors.forename: Eero
authors.initials: E
authors.lastname: Kyllönen
authors.forename: Antti M
authors.initials: AM
authors.lastname: Kiviniemi
authors.forename: Mikko P
authors.initials: MP
authors.lastname: Tulppo
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hautala
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D012017:Referral and Consultation / Q000639:trends; D012585:Sciatica / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery