Balance deficits in Chronic Fatigue Syndrome with and without fibromyalgia

OBJECTIVE: Chronic Fatigue Syndrome (CFS) is a disorder of unknown etiology associated with debilitating fatigue. One symptom commonly reported is disequilibrium. The goal of this study was to determine if CFS patients demonstrated verified balance deficits and if this was effected by comorbid fibromyalgia (FM). METHODS: Twenty-seven patients with CFS (12 with comorbid FM) and 22 age and gender matched controls performed posturography. RESULTS: Balance scores were significantly correlated with physical functional status in the CFS group (R 2 =0.43, P<0.001), which was not found for mental functional status (R 2 =0.06, P>0.5). CFS patients (regardless of FM) had significantly higher anxiety subscale of the vertigo symptom scale scores. CFS patients, regardless of FM status, demonstrated significantly lower overall composite balance scores (Controls - 78.8±1.5; CFS - 69.0±1.4, P<0.005) even when controlling for anxiety and also had worse preference scores, indicating they relied on visual information preferentially even when visual information was incorrect. Interestingly, the CFS+FM group, not CFS only, demonstrated significantly worse vestibular scores (Controls - 70.2±2.4; CFS only - 67.9±3.8; CFS with FM - 55.4±4.6, P=0.013). INTERPRETATION: The major findings are that poor balance may be associated with poorer self-reported physical health. In addition, CFS patients seemed to rely preferentially on visual inputs, regardless of whether it was correct. The finding that vestibular function may be impaired in patients with CFS+FM but not in those with CFS alone suggests that the pathophysiology of CFS+FM may differ as has been suggested by some.