title: Dysautonomia and heart rate variability following severe traumatic brain injury.
abstract: OBJECTIVE
  To investigate disconnection theories postulated as the cause of dysautonomia following severe traumatic brain injury (TBI) through analysis of heart rate variability (HRV).
  
  
  METHODS
  Data were collected on age-matched subjects with and without dysautonomia (eight subjects in each group) and 16 non-injured controls. Data included injury details, continuous electrocardiograph recordings and rehabilitation outcome.
  
  
  RESULTS
  The TBI group revealed significant differences in HRV parameters both compared to controls and between dysautonomic and non-dysautonomic subjects. Additionally, HRV parameters for dysautonomic subjects showed evidence of an uncoupling of the normal relationship between heart rate and sympathetic/parasympathetic balance. HRV changes persisted for the dysautonomia group for a mean of 14 months post-injury.
  
  
  CONCLUSIONS
  Dysautonomic subjects revealed prolonged uncoupling of heart rate and HRV parameters compared to non-dysautonomic subjects and controls. These findings represent direct pathophysiological evidence supporting the disconnection theory postulated to produce dysautonomia following TBI.
authors.affiliation: Brain Injury Rehabilitation Service, Westmead Hospital, Westmead, NSW, Australia. ianb@biru.wsahs.nsw.gov
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Baguley
authors.forename: Roxana E
authors.initials: RE
authors.lastname: Heriseanu
authors.forename: Kim L
authors.initials: KL
authors.lastname: Felmingham
authors.forename: Ian D
authors.initials: ID
authors.lastname: Cameron
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000209:etiology / Q000503:physiopathology*; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology*; D016022:Case-Control Studies; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology