Evaluation of Sleep Disordered Breathing and Autonomic Dysfunction in Fibromyalgia Through Peripheral Arterial Tonometry

Fibromyalgia Syndrome (FMS) is a clinical entity characterized by the presence of chronic, widespread pain and tenderness throughout the musculoskeletal system. FMS is considered to be a prototype of central pan syndromes, conditions in which augmentation of pain processing by the central nervous system in a major feature (1;2). As such, FMS overlaps with a number of similar "functional" disorders, including TMJD, IBS, Interstitial cystitis, Gulf war syndrome, chronic fatigue syndrome etc (3-5).

A major clinical feature of FMS is the presence of chronic fatigue, which is typically accompanied by a severely disrupted sleep pattern. Difficulty falling asleep, frequent awakening and non-refreshing sleep are all features classically reported by FMS patients. In addition, a number of classic sleep disturbances have been identified among FMS patients such as alpha - wave intrusion, disrupting normal stage IV sleep, as well as nocturnal falls in oxygen saturation (6). Notably, disturbed sleep may contribute not only to chronic fatigue, but also to enhanced pain processing as well as depression in FMS patients (7). Thus, pain inhibitory functions of the CNS, such as the process of Diffuse Noxious Inhibitory Control (DNIC) appear to be impaired in by sleep disruption (8).

Considerable interest has focused on the role of sleep apnea in FMS, as a possible factor contributing to fatigue and pain. Overt obstructive sleep apnea has been diagnosed in some patients (9) while more subtle disruptions of upper airway dynamics, such as increased upper airway pressure, not leading to total airway collapse, has been detected in many patients (10). Other researchers however have challenged the association of FMS with sleep apnea (11).

Autonomic dysfunction is another important clinical manifestation of FMS with common symptoms including presyncope / syncope, palpitations on standing and dizziness (12). Postural Orthostatic Tachycardia Syndrome (POTS) is another autonomic disorder which clinically overlaps with FMS (13).

Traditional polysomnography is a time-consuming and costly procedure, and hence, relatively few FMS patients are formally evaluated for sleep disorders in clinical practice.