Evaluation of psychophysiological asymmetry in patients with fibromyalgia syndrome.

Fibromyalgia syndrome (FMS) is characterized by systemic pain of unknown etiology, and is often accompanied by various psychological symptoms. In the present study, differences in surface electromyographic (SEMG) levels of the trapezius muscle, skin temperature (TEMP) and skin conductance level (SCL) were compared between the right and left side of the body in 31 FMS and 47 control subjects (Control Group). We observed significant asymmetries of SEMG level, TEMP and SCL in the FMS Group. These asymmetries might be related to central, peripheral and autonomic nervous system dysfunctions. Marked increase of SEMG levels, and a decrease of TEMP and SCL were observed at the dominant side in the FMS Group, and a negative correlation of SEMG levels with TEMP and SCL was found. These results suggest that continued antalgic postures in response to pain at the dominant side in FMS patients might lead to asymmetries of SEMG level, TEMP and SCL. Thus, a focus on pain related behaviors and muscle asymmetry might be a useful therapeutic approach.

Paradoxical results of psychophysiological stress profile in functional somatic syndrome: correlation between subjective tension score and objective stress response.

Mind-body interactions are important in functional somatic syndromes (FSS). Therefore, in the assessment of the psychophysiological stress response in patients with FSS, both subjective feelings and psychophysiological activity should be simultaneously measured. In this study, "Objective Tension Score" (OTS) was defined as an objective parameter of tension; it consisted of surface electromyography and skin conductance level as indicators of muscle and mental tension, respectively. "Subjective Tension Score" (STS) was defined as a subjective parameter of tension. Changes in OTS and STS in response to the stress task were investigated in 30 FSS patients and 28 controls. Objective tension was significantly hyporeactive to the stress task and STS was significantly higher in the patient group than in the control group. There was a significant negative correlation between OTS response and STS in the patient group, but no significant correlation in the control group. Our results suggested the existence of dissociation between subjective and objective responses in FSS patients. This may indicate that FSS patients had difficulty with the awareness of bodily feelings, thus supporting the concept of "alexisomia" or "escaped bodily feelings" in FSS patients.