A mental disorder where physical symptoms are converted to a neurological problem affecting motor or sensory function is defined as a conversion disorder.

The onset of the disorder usually occurs before a psychologically very stressful event. It is more common in rural populations, individuals of lower socioeconomic status, and individuals less knowledgeable about medical and psychological concepts. It occurs more frequently in women than in men.

The symptoms develop unconsciously and may include paralysis, blindness, deafness, difficulty in swallowing, simulated convulsions or loss of sensation or both. The symptom must be severe enough to interfere with the patient's social or other important areas of functioning. Episodes are brief, and patients show a lack of concern.

Many tests are ordered to rule out physical disease. When the test results are negative, then conversion disorder is possible. Conversion symptoms rarely follow a true anatomic and physiologic textbook picture. Diagnostic criteria for the condition are as follows:

• One or more symptoms or deficits that affect the voluntary motor or sensory functions.

• Onset of the symptoms is preceded by other stressors.

• The symptom of deficit is not intentionally produced or faked, and it cannot be explained by a general medical condition or the effects of a substance.

• The symptom of deficit causes significant loss of function in social, occupational, or other areas of functioning to warrant investigation.

• The symptom of deficit is not limited to pain or sexual dysfunction, and is not better classified as another mental disorder.

The essential component in treatment is a trusting, physician-patient relationship. When the physician has excluded all the physical possibilities and has convinced the patient there is no serious physical disorder, the patient improves and symptoms fade. If a distressing situation has precipitated the symptom onset, then psychotherapy can sometimes be effective. Behavior modification, hypnosis, or narcoanalysis have roles in treatment of the condition.

Recurrence is common, and it occurs in approximately 25% of individuals within one year. The symptoms associated with a good prognosis are paralysis, blindness and aphonia (loss of speech sounds); those who present with tremors and seizures do not often have as good a prognosis.