Decreased autonomic nervous system activity as assessed by heart rate variability in patients with chronic tetraplegia.
OBJECTIVE
To assess the alterations of autonomic nervous functions and sympathovagal balance of the subjects with spinal cord injuries (SCIs) in different levels by heart rate variability analysis.


METHODS
Prospective, observational study.


METHODS
All participants were recruited from the outpatient clinic from National Taiwan University Hospital, which is a tertiary referral center.


METHODS
Thirty-one patients with traumatic chronic complete SCI (more than 6 months): 14 with paraplegia (Group A), and 17 with tetraplegia (Group B).


METHODS
Heart rate variability assessed by 24-hour Holter monitoring.


RESULTS
Two patients in Group A and 1 in Group B were excluded from final data analysis because of poor recording data. Two time domain variables, the standard deviation (SD) of all normal RR intervals (SDNN) and the mean of the SDs of all normal RR intervals for all 5-minute intervals (SDNNi), over 24 hours were decreased in Group B. All time domain variables, SDNN, SDNNi, root mean square of the successive normal RR interval difference (rMSSD), and the percentage of RR intervals differing >50msec from the preceding one (pNN50), were decreased during the nighttime recordings (all p < .05) in Group B. The very-low-frequency, low-frequency (LF), and high-frequency (HF) components of the power spectrum of the RR intervals were also decreased in Group B (p < .05), irrespective of the daytime and nighttime recordings. The LF-to-HF ratio did not differ significantly in these two groups, indicating the maintained sympathovagal balance in the chronic SCI patients.


CONCLUSIONS
These findings suggested that the autonomic nervous system activity was depressed in the patients with chronic tetraplegia, but the autonomic nervous system still maintained homeostasis.
Wang
Y H
YH
Department of Physical Medicine and Rehabilitation, College of Medicine, National Taiwan University, Taipei.
Huang
T S
TS
Lin
J L
JL
Hwang
J J
JJ
Chan
H L
HL
Lai
J S
JS
Tseng
Y Z
YZ
D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002908:Chronic Disease; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006706:Homeostasis; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011782:Quadriplegia / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*