Abstract
Introduction
There is some data that pain patients may have impaired autonomic nervous system function assessed by heart rate variability (HRV). However, only few studies have evaluated the effect of low back disorders on HRV. In this study, we evaluated whether HRV differs between sciatica patients referred to spine surgery and age-matched healthy controls.
Materials and Methods
We measured HRV in standing position (5 minutes) after 10 minutes rest for patients (n = 201, age 42 ± 11 years, 113 men and 88 women) and healthy controls (n = 138, age 42 ± 11 years, 39 men and 99 women). Vagally mediated high frequency (HF) power of R-R intervals and low-to-high frequency (LF/HF) ratio as an index of sympathovagal balance were analyzed. Pain intensity was assessed by 100-mm visual analog scale (VAS) and perceived disability by Oswestry low back pain disability index. Analysis of variance and chi-square test were used to analyze differences between groups, and correlation analysis for the associations between pain and HRV.
Results
Oswestry index (37 ± 14 vs. 2 ± 3%) and VAS (5.8 ± 2.5 vs. 0.6 ± 1.0 cm) differed between the patients and controls (p < 0.0001 for both). Body mass index was higher (p < 0.0001) in patients (26.4 ± 4.4 kg/m2) compared with controls (23.9 ± 3.6 kg/m2). There were more smokers among patients (p < 0.0001) and gender distribution differed between the groups (p < 0.0001). Groups did not differ from each other in relation to physical activities and comorbidities. HF power was 4.5 ± 1.2 ln ms2 for patients and 5.1 ± 1.2 ln ms2 for controls (p < 0.0001). LF/HF ratio was higher in patients (7.9 ± 6.4) compared with controls (5.8 ± 5.2) (p = 0.002). After adjusting with sex, smoking, and BMI, HF power still differed between the groups (p = 0.003), but the difference between groups disappeared in LF/HF power (p = 0.134). Among patients, Oswestry index and VAS did not correlate with HRV (r = −020 to −061).
Conclusion
Sciatica patients referred to spine surgery had decreased vagal activity compared to age-matched healthy controls. Impaired functional capacity caused by pain or pain intensity were not associated with vagal activity among patients.
Yes
None declared