Exposure to Cold Unmasks Potential Biomarkers of Fibromyalgia Syndrome Reflecting Insufficient Sympathetic Responses to Stress

METHODS In a pilot study, blood pressure (BP), skin temperature, thermogenic activity, circulating glucose, and pain sensitivity of 13 patients and 11 controls at room temperature (24°C) were compared to that after exposure to cold (19°C).

RESULTS When measured at 24°C, BP, skin temperature, blood glucose and brown adipose tissue (BAT) activity, measured using F-fluorodeoxyglucose (FDG) PET/CT, did not differ between controls and patients with FMS. However, after cold exposure (19°C), BP and BAT activity increased in controls but not in FMS patients; skin temperature on the calf and arm decreased in controls more than in FMS patients; and circulating glucose was lower in FMS patients than in controls. Pain sensitivity did not change during the testing interval in response to cold.

DISCUSSION The convergence of the effect of cold on four relatively simple measures of thermogenic, cardiovascular and metabolic activity, each regulated by sympathetic activity, strongly indicate that patients with FMS have impaired sympathetic responses to stress that are observable and highly significant even when measured in extraordinarily small sample populations. If insufficient sympathetic responses to stress are linked to FMS, stress may unmask and maximize these potential clinical biomarkers of FMS and be related to its etiology.