Dominance of the Sympathetic Nervous System in Patients with Fibromyalgia/Chronic Fatigue Syndrome Compared to Healthy Controls

Abstract

Background. A dominance of the sympathetic nervous system (SNS) is hypothesized to play a crucial role in the etiology and perpetuation of functional somatic syndromes. However, literature on this topic is still inconsistent. Objectives. The aim of our study was to examine physiology of the autonomic nervous system (ANS) by measuring heart rate (HR), skin conductance (SC), and peripheral skin temperature (ST) in response to psychosocial stressors in patients with fibromyalgia/chronic fatigue syndrome (CFS) and healthy controls (HC). Methods. Patients with fibromyalgia/CFS (n=26) and HC (n=30) went through a stress test consisting of a baseline phase (120s), a Stroop Color and Word Test (120s), a mental arithmetic task (120s) and a stress talk (120s). Each stressor was followed by a 120s recovery period. HR, SC, and ST were monitored continuously. Random intercept random slope linear mixed model analyses were performed on the different phases. Results. Our main findings were that fibromyalgia/CFS patients had a significantly higher HR during all phases compared to HC. Fibromyalgia/CFS patients also had significantly higher SC compared to HC during all phases. No significant difference was found between fibromyalgia/CFS patients compared to HC regarding ST. Conclusion. Our results showed a dominance of the SNS regarding HR and SC in fibromyalgia/CFS patients compared to HC, suggesting the presence of ANS dysfunctionalities as an underlying working mechanism of fibromyalgia/CFS.