Sympathetic and parasympathetic activities evaluated by heart-rate variability in head injury of various severities

Chain Fa Su, Terry B. Kuo, Jon Son Kuo, Hsien Yong Lai, Hsing I. Chen

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Objective: To investigate the autonomic function in patients with brain damage of various extents. The purposes were to correlate the parameters derived from spectral analysis of the heart-rate variability (HRV) with the classic Glasgow coma scale (GCS), and to evaluate the possible clinical application of HRV in the autonomic functions in patients with various severities of brain-stem injury. Methods: A total of 90 patients was divided into 5 groups based on the GCS: I: 15, II: 9-14, III: 4-8, no pupil dilatation, IV: 4-8, pupil dilatation, and V: 3, brain death. Electrocardiogram was recorded for frequency-domain analysis of RR intervals. HRV were categorized into the low-frequency (LF, 0.04-0.15 Hz) and high-frequency power (HF, 0.15-0.40 Hz), LF to HF power ratio (LF/HF), normalized powers (LF and HF%). These HRV parameters were correlated with the severity of brain damage. Results: The LF, HF, LF%, and LF/HF in Group I were essentially similar to those in the normal subjects. LF and HF decreased from Group I to IV. All parameters were nearly absent in Group V. Conclusions: The increases in LF% and LF/HF with the decrease in HF indicate augmented sympathetic and attenuated parasympathetic drive. These changes were related to the severity of brain-stem damage. Both LF and HF were nearly abolished in brain death. Significance: Our analysis indicates that HRV may be an useful tool for evaluating the autonomic functions in patients with brain damage of various degrees.

Original languageEnglish
Pages (from-to)1273-1279
Number of pages7
JournalClinical Neurophysiology
Issue number6
Publication statusPublished - Jun 2005
Externally publishedYes



  • Autonomic function
  • Brain-stem
  • Critical care
  • Heart-rate variability
  • Intracranial hypertension
  • Power spectral analysis

ASJC Scopus subject areas

  • Sensory Systems
  • Neurology
  • Clinical Neurology
  • Physiology (medical)

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