Functional Somatic Syndromes

The term functional somatic syndrome refers to several related syndromes that are characterized more by symptoms, suffering, and disability than by disease-specific, demonstrable abnormalities of structure or function. Physicians in many medical specialties are increasingly confronted by patients who have disabling, medically unexplained, somatic symptoms and who have already arrived at a diagnostic label for their illness. The functional somatic syndromes have acquired major sociocultural and political dimensions. Their definitive status in public consciousness and popular discourse contrasts markedly with their still uncertain scientific and biomedical status. Patients with these syndromes often have very explicit disease attributions for their symptoms, and they resist information that contradicts these attributions (1, 2). These patients often have a strong sense of assertiveness and embattled advocacy with respect to their etiologic suppositions, and they may devalue and dismiss medical authority and epidemiologic evidence that conflicts with their beliefs (3). The functional somatic syndromes include multiple chemical sensitivity, the sick building syndrome, repetition stress injury, chronic whiplash, chronic Lyme disease, the side effects of silicone breast implants, candidiasis hypersensitivity, the Gulf War syndrome, food allergies, mitral valve prolapse, and hypoglycemia. The incidence of several other functional somatic syndromes has apparently declined: chronic carbon monoxide poisoning; chronic mononucleosis; and symptoms resulting from exposure to video display terminals, carbonless copy paper, and weak electromagnetic fields. In three other syndromesthe chronic fatigue syndrome, fibromyalgia, and the irritable bowel syndromemore uncertainty exists about the presence of demonstrable pathophysiology, but these syndromes are included in this review because they have extensive phenomenologic overlap with other functional somatic syndromes and the psychosocial factors discussed here apply to them. Methods English-language articles were identified through a search of the MEDLINE database from 1966 to the present. The bibliographies of the retrieved articles were then searched for additional publications. Standardized or structured analysis of the identified papers was not possible because of variation in quality, design, and methods and because of the breadth of the articles included. Emphasis was given to empirical studies that used more rigorous diagnostic methods, larger samples, systematic analyses, appropriate comparison groups, and longitudinal follow-up. The funding source for this work had no role in the collection, analysis, or interpretation of data or in the decision to submit the paper for publication. Historical Context In the past, various conditions associated with the symptoms of functional somatic syndromes (such as headache, musculoskeletal pain, fatigue, gastrointestinal distress, memory difficulties, and insomnia) have arisen, attracted intense medical attention, and then declined in incidence. Neurasthenia, spinal irritation, chronic brucellosis, pinched nerves, railway spine, and soldier's heart were each initially thought to have a medical cause, but when no pathologic basis for these conditions could be established, they subsequently declined in incidence and prevalence. More recently, functional somatic syndromes such as mercury poisoning caused by dental fillings, symptoms resulting from use of video display terminals, and chronic mononucleosis have declined in popularity. Somatic distress and medically unexplained symptoms have always been endemic to daily life, but the social and cultural characteristics of each era shape the expression, interpretation, and attribution of these symptoms. Thus, similar constellations of benign symptoms acquire different diagnostic labels and are attributed to different causes in different time periods (1, 3). A line of descent can be traced from the DaCosta syndrome through soldier's heart, shell shock, and battle fatigue to the Gulf War syndrome (4). Musculoskeletal pain in the workplace, which previously manifested as writer's cramp and telegraphist's wrist, is now termed repetition strain injury (5). There are similarities between railway spine, common in the early 20th century, and the more recent chronic whiplash syndrome (6). Although the functional somatic syndromes are not new, patients who have these syndromes today differ from their predecessors by being less relieved by negative findings on medical evaluation and less responsive to explanation, reassurance, and palliative treatment (1, 7, 8). Several factors may account for this shift. First, the authority and prestige of the physician have declined: The reassurance of one's personal physician and the opinions of medical and public health authorities are no longer as calming, reassuring, and palliative as they once were. With this erosion of physician authority and the increasing prevalence of a generalized antiscientific attitude (7), the determination that a functional somatic syndrome has no pathologic basis does not result in a rapid decline in the incidence of that syndrome, as it did in the past (8). This divergence of medical and scientific evidence and public opinion is particularly evident in the recent controversy over silicone breast implants (7). Second, the current situation is powerfully shaped by the mass media (7-9), which often use hyperbole and uncritical reporting to portray the functional somatic syndromes (3, 7, 10, 11). Preliminary data, tentative findings, and the personal accounts of individual sufferers are reported as conclusive medical evidence (3, 12). The functional somatic syndromes are described as rapidly spreading epidemics, progressive and incapacitating, and some reports insinuate that powerful societal institutions are denying the existence of these syndromes to conceal their own negligence or culpability (3, 11). Such sensationalism and alarmism promote symptoms and distress (5, 13-17). Finally, the contemporary climate is marked by the prominent political, legal, economic, and regulatory ramifications of the functional somatic syndromes (18-20). Individuals and organizations have strong vested interests in the status of these syndromes, and the actions of these persons and groups may reinforce sufferers' beliefs that their symptoms have a medical basis (21-24). The functional somatic syndromes form the basis for lawsuits and class actions seeking to attribute liability and fault. Medical specialists and clinics develop professional and financial stakes in one syndrome or another. Advocacy groups emerge to mobilize public opinion, influence scientific debate, and shape public policy. The functional somatic syndromes are a source of disputes over health insurance coverage; may propel the creation of environmental, occupational, and workplace regulations; and may qualify sufferers for worker's compensation or disability benefits. Overlap and Common Characteristics Each functional somatic syndrome is seen in a heterogeneous group of patients. In some patients, symptoms are attributable to a known disease entity; in others, they result from an unrecognized disorder that may involve physiologic or immunologic hyperreactivity and perceptual hypersensitivity. Other patients have symptoms that are caused by a psychiatric disorder, and still others have symptoms that are best understood as a response to stressful life circumstances. Our knowledge of the functional somatic syndromes is incomplete, and we do not fully understand the etiologic roles of biological, psychological, and sociocultural factors in these syndromes. Although complex, poorly understood, and heterogeneous, the functional somatic syndromes nonetheless have enough in common to justify our discussing them together as variants of a common biopsychosocial process. The similarities seen in the functional somatic syndromes have led some to propose that they share a common pathophysiology. Thus, they have been conceptualized as variants of affective spectrum disorder because a significant fraction of patients who have these syndromes respond to antidepressant medications of different, unrelated chemical classes (25-27). It has also been suggested that the functional somatic syndromes all involve the same pathophysiologic dysregulation and blunting of the central nervous system's response to stress (28). Further research may shed light on these interesting hypotheses, but they are currently largely speculative. Phenomenology Although individual functional somatic syndromes may present with some organ-specific symptoms and may differ with respect to which symptoms are most prominent (for example, neck pain in chronic whiplash and gastrointestinal symptoms in the irritable bowel syndrome), they generally lack characteristic clinical presentations or distinct symptom complexes that are consistent across cases and that distinguish the syndromes from one other (29, 30). The various functional somatic syndromes have remarkably similar symptoms that share two important characteristics: They are diffuse, nonspecific, and ambiguous, and they are very prevalent in healthy, nonpatient populations (31). Symptoms common to the functional somatic syndromes include fatigue; weakness; sleep difficulties; headache; muscle aches and joint pain; problems with memory, attention, and concentration; nausea and other gastrointestinal symptoms; anxiety; depression; irritability; palpitations and racing heart; shortness of breath; dizziness or light-headedness; sore throat; and dry mouth. All of these symptoms have a high incidence in the general population. Surveys of healthy persons who are not patients show that fatigue, headache, joint aches and stiffness, upper respiratory symptoms, and diarrhea are common and generally resolve spontaneously, usually within 1 month (32). Significant fatigue, for example, is rep