Autonomic testing in patients with Chronic Fatigue Syndrome (CFS)

The purpose of this study was to determine whether chronic
fatigue syndrome (CFS) patients show autonomic dysfunction at
the cardiac level and if so, to discover whether these
abnormalities explain the fatiguability and/or other symptoms
in CFS. The study population consisted of 21 CFS patients
(Centers for Disease Control and Prevention [CDC] criteria,
1988) and 13 age- and sex-matched healthy controls. The
autonomic testing consisted of: (1) postural challenge:
registration of heart rate and blood pressure (BP) and heart
rate variability in supine and in upright position (tilted to
70 degrees); (2) Valsalva maneuver; (3) handgrip test; (4)
cold pressor test; and (5) heart rate response to deep
breathing. Statistical analysis was performed using the Mann
Whitney rank sum test; results of the test were considered
significant at the 0.05 level. After tilting heart rate was
significantly higher in CFS patients compared with healthy
controls (mean CFS = 88.9 beats/min vs control = 77.9
beats/min; P <0.01). Low frequency power after tilting was
significantly higher in CFS patients compared with controls
(mean CFS = 0.603 vs control = 0.428; P = 0.02). There was a
trend toward an increased heart rate during the cold pressor
test. Other parameters did not differ between the CFS and
control populations. The observed changes point toward a
sympathetic overactivity in CFS patients when they are exposed
to stress. Parasympathetic abnormalities could not be
observed. Therefore, our findings provide no real explanation
for the fatigue and intolerance to physical exertion in these

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