Short-term assessment of autonomic nervous system as a potential tool to quantify pain experience

Various pain conditions may result in altered autonomic nervous system regulation. We evaluated whether autonomic regulation, analyzed with short-term heart rate variability (HRV), differs between low back pain (LBP) patients and healthy controls. Additionally, we tested if short-term HRV recordings are feasible and informative in planning home monitoring of LBP patients. The study population consisted of 16 volunteers (8 LBP patients and 8 healthy subjects) (age 42±10 years, body mass index 26±4 kg/m2, 7 men and 9 women). Usually 3- to 5-minute R-R interval recordings have been used as short-term recordings of HRV, but recent evidence supports even shorter R-R interval recording procedure for short-term HRV assessment. We collected R-R interval data for 1 minute in sitting, standing and bending down tasks. Mean heart rate (HR) and vagally mediated beat-to-beat variability (SD1 and rMSSD) were analyzed. The results showed that autonomic nervous system function assessed with the short-term measurement HRV method differentiates LBP patients from healthy controls in sitting and standing. Vagally mediated SD1 and rMSSD were significantly lower and the HR was higher among the patients compared to the controls. A novel finding was also the feasibility of 1-minute measurement of HRV, which may open entirely new opportunities to assess accurately concomitant changes in autonomic nervous system function and self-reported individual pain experience. This could lead to a more personalized pain treatment and more efficient health care resource allocation as the new measurement methods is more suitable for home monitoring than the previously used ones.