Autonomic function in patients with chronic fatigue syndrome

Abstract

Subtle signs of autonomic dysfunction and orthostatic intolerance have been reported in patients with chronic fatigue syndrome (CFS). To assess cardiovascular autonomic function noninvasively in an unselected group of patients with CFS, we examined responsiveness to several cardiovascular reflex tests in 37 CFS patients and 38 healthy control subjects. Blood pressure and heart rate (HR) were recorded continuously by a Finapres device before and during forced breathing, standing up, Valsalva maneuver, and sustained handgrip exercise (HG). In addition, a mental arithmetic test was carried out and questionnaires to assess the severity of CFS symptoms were completed. At rest, there were no significant differences in blood pressure or in HR between the two groups. The in- and expiratory difference in HR tended to be lower in CFS patients (28.4 +/- 10.5 beats) than in healthy controls (32.2 +/- 9.5) (p = 0.11). The maximal increase in HR during standing up was not significantly different between the CFS group (37.6 +/-8.9 beats) and the control group (40.2 +/- 8.9 beats). There were no significant differences between both groups with regard to the Valsalva ratio, but the systolic and diastolic blood pressure responses were significantly larger in CFS patients, despite the fact that many CFS patients were not able to sustain the Valsalva maneuver. The HR response to MA was significantly less in the CFS group (22.6 +/- 9.9) than in the control group (29.5 +/- 16.7) (p < 0.05), suggesting impaired cardiac sympathetic responsiveness to mental stress. The lower HR responses could not be explained by the level of concentration in the CFS group. During HG exercise, the hemodynamic responses were lower in the CFS group than in the control group, but this might be attributed to the lower level of muscle exertion in CFS patients. There were no significant differences between CFS patients with and without symptoms of autonomic dysfunction regarding the hemodynamic responses to the cardiovascular reflex tests. The findings of the study suggest that there are no gross alterations in cardiovascular autonomic function in patients with CFS.

Stress as a Pathophysiological Factor in Functional Somatic Syndromes

“…This is in accordance with other studies showing low vagal tone [112,[118][119][120] and a general sympathetic overactivity [105,121,122]. However, there are also reports on decreased heart rate in response to exercise [123] or mental stress [124], or no differences between CFS and healthy controls at all [104,121,124]. A previous study [125] has shown increased salivary alpha-amylase (which is thought to reflect sympathetic activation) activity in CFS patients compared to healthy controls, both at baseline and after a psychosocial stress test in the laboratory.…”

Myalgic encephalomyelitis/chronic fatigue syndrome and encephalomyelitis disseminata/multiple sclerosis show remarkable levels of similarity in phenomenology and neuroimmune characteristics

“…Another study demonstrated impaired HR responses indicating the existence of attenuated cardiac sympathetic responsiveness. These lower HR responses could not be reconciled with an explanation based on patient deconditioning or prolonged inactivity [19]. Those authors reported that hemodynamic responses in patients with ME/CFS were significantly impaired during exercise compared to healthy controls.…”

A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and sickness behavior

“…[34] detected a sympathetic drive mediated increased heart rate on tilt compared to healthy controls. Another study demonstrated impaired heart rate responses to exercise coupled with globally impaired hemodynamic responses incompatible with patient deconditioning or prolonged inactivity [35]. Several other authors have reported autonomic dysfunctions in people with ME/CFS [36-38].…”