Epidemiology

Somatoform conditions include the following diagnoses: somatization disorder, conversion disorder, somatoform pain disorder, hypochondriasis, body dysmorphic disorder, and undifferentiated somatoform illness. The boundaries between these disorders can be subtle, and it has recently been proposed that four of these conditions—somatization disorder, somatoform pain disorder, hypochondriasis, and undifferentiated somatoform illness—should be reclassified under a single common rubric called complex somatic symptom disorder (CSSD).¹ Further classification of somatoform disorders is continually evolving as research better defines their distinctive characteristics.^1–3

The reported prevalence of somatoform conditions ranges from 50% to 65% in ambulatory settings.^4,5 When definitions are narrowed to include only patients meeting strict diagnostic criteria for somatization disorder, the lifetime prevalence drops to less than 3%.⁶ Accurate classification is difficult because some patients exhibit somatoform symptoms in the presence of demonstrable medical illness.

True somatization disorder (or Briquet syndrome, after Paul Briquet, who first described the illness in 1859) is typically manifested before 30 years of age and is far more common in women than in men. Although many patients somatize, somatization disorder is ultimately diagnosed in few.

Definitions

Somatization disorder is characterized by the presence of multiple chronic distressing somatic symptoms that are not medically explained. Patients with this condition tend to be highly anxious about their symptoms, even in the face of evidence that their condition is not medically serious. In the draft of the upcoming Diagnostic and Statistical Manual of Mental Disorders (DSM-V), this condition has been renamed CSSD.¹

Hypochondriasis is preoccupation with or excessive fear of illness despite negative testing and reassurance from a health care professional. Hypochondriasis is more common than somatization disorder and has a prevalence of 4% to 9% in general medical practice.⁷ It peaks in men in the fourth decade and in women in the fifth, with no significant predilection by gender. Hypochondriasis is increasingly being described in geriatric populations.⁸ It has been renamed the “predominant health anxiety” subtype of CSSD in the proposed draft of DSM-V.¹

Somatoform pain disorder, an important and particularly challenging somatoform illness, is characterized by somatoform symptoms that are manifested predominantly as pain. In the proposed draft of DSM-V, this condition is reclassified as the “predominant pain” subtype of CSSD.¹

Conversion disorder is a condition in which patients complain of sensory or motor symptoms as a manifestation of stress or unconscious conflict that cannot be attributed to a pathophysiologic process. Conversion disorder is more common in women and members of lower socioeconomic groups. Its onset typically begins in adolescence, and it follows a discontinuous course. Conversion disorder has also been observed in military, mass casualty, and industrial accident settings without a female preponderance of the disorder.⁹ Estimates of prevalence vary considerably as a result of inconsistent classifications and definitions of the disorder.

Body dysmorphic disorder is characterized by a preoccupation with an imagined defect in physical appearance. Although it is currently classified under somatoform disorders, body dysmorphic disorder more closely resembles obsessive-compulsive disorder and as a result may be moved to the anxiety disorders section of the DSM-V.¹ This disorder is commonly encountered by primary care providers, plastic surgeons, and the body enhancement industry.

Factitious disorders, including malingering, feature deliberate manufacturing of symptoms or illness. The combined prevalence of all factitious disorders ranges from 1% to 5%, again with a female preponderance. The term Munchausen syndrome (after the famous 18th-century raconteur Baron von Munchausen) is reserved for chronic or “career” medical imposters, and it represents the extreme form of the disorder. However, cases of Munchausen syndrome tend to involve male patients.¹⁰

Malingering and symptom exaggeration are probably underreported. In one study, “39% of mild head injury, 35% of fibromyalgia/chronic fatigue, 31% of chronic pain, 27% of neurotoxic, and 22% of electrical injury claims resulted in diagnostic impressions of probable malingering.”¹¹ Malingering is most often exhibited by patients who are either trying to avoid an unpleasant circumstance, such as military duty or a prison term, or attempting to secure some form of compensation, such as occupational health or personal injury plaintiff claims. Malingering can result in criminal charges.¹²

Factitious disorder by proxy or Munchausen syndrome by proxy deserves special mention because it may represent a form of child abuse. It is typically defined as the intentional production or feigning of physical or psychiatric illness in a child by the child’s guardian, although it has also been reported in caregivers of geriatric patients. Factitious disorder by proxy can be active (symptom producing) or passive (neglect). Munchausen syndrome by proxy is rare and occurs in roughly 2.8 per 100,000 children younger than 1 year and 0.5 per 100,000 children younger than 16 years.¹³ As with the other factitious illnesses, the deceptive nature of the disorder makes it extremely difficult to detect and study.

Pathophysiology

Somatoform illnesses represent emotional stress experienced as physical symptoms. Both somatization and hypochondriasis are commonly associated with depression and anxiety, and somatization is classified as a potential initial symptom of depression.¹⁴ This strong association with depressive disorders has led to the practice of treating somatization with antidepressant medications. Hypochondriasis and depression coexist in roughly 40% of cases. Twenty percent of patients with hypochondriasis have a diagnosis of panic disorder, and 10% have an obsessive-compulsive disorder.¹⁵ As the number of reported physical symptoms rises in patients with somatoform illness, the likelihood of an underlying psychiatric disorder increases proportionately.¹⁶

A significant correlation does not appear to exist between psychiatric illness and factitious disorder, unlike somatization and hypochondriasis. Malingering is observed in individuals with antisocial and psychopathic personalities, but the nature of this association remains unclear.

Presenting Signs and Symptoms