a type of mental disorder in which a wide variety of sensory, motor, or psychic disturbances may occur. It is traditionally classified as one of the psychoneuroses and is not dependent upon any known organic or structural pathology. The former term, hysteria, is derived from the Greek hystera, meaning “uterus,” and reflects the ancient notion that hysteria was a specifically female disorder resulting from disturbances in uterine functions. Actually, the symptoms of conversion disorder may develop in either sex and may occur in children and elderly people, although they are observed most commonly in early adult life.

Conversion disorder, in its clinically pure form, seems to occur more often among the psychologically and medically naive than among sophisticated persons. The incidence of conversion disorder appears to be diminishing in many areas of the world, probably because of cultural factors such as increasing psychological and medical awareness among the general public. Cases of classical conversion disorder, such as those frequently described by 19th-century clinicians, have become rare. Most psychoneuroses encountered in actual clinical practice are apt to be “mixed” forms in which symptoms of conversion disorder may be found interspersed with other varieties of neurotic disturbances. Isolated conversion disorder symptoms may also occur in conjunction with psychotic disorders.

The sensory and motor manifestations of conversion disorder take many forms and are designated conversion reactions because the underlying anxiety is assumed to have been “converted” into physical symptoms. Sensory disturbances may range from paresthesias (“peculiar” sensations) through hyperesthesias (hypersensitivity) to complete anesthesias (loss of sensation). They may involve the total skin area or any fraction of it, but the disturbances generally do not follow any anatomic distribution of the nervous system. In medieval times in Europe and as late as the end of the 17th century, the finding of such discrete areas of anesthesia on the body of a person was considered proof that the person was a witch. Other sensory disturbances associated with conversion disorder may encompass the special senses of vision, hearing, taste, or smell; or they may involve the experiencing of severe pain for which no organic cause can be determined.

Motor symptoms vary from complete paralysis to tremors, tics, contractures, or convulsions. In each instance neurological examination of the affected part of the body reveals an intact neuromuscular apparatus with normal reflexes and normal electrical activity and responses to electrical stimulation. Other motor disturbances that are at times associated with conversion disorder are loss of speech (aphonia), coughing, nausea, vomiting, or hiccuping.

Psychic symptoms may be equally varied and are usually classified under the broad heading of dissociative reactions. Attacks of amnesia, in which the person is unable to remember who he is or anything about himself, are among the more striking of these. sleepwalking (somnambulism) is also considered to be a dissociative reaction, as are also the occasional dramatic cases of multiple personality. (See mental disorder: Dissociative disorders (mental disorder).)

Treatment of conversion disorder involves psychotherapy, the focus of which is to bring to the patient's consciousness those feelings, ideas, and conflicts that are causing the symptoms. Support and reassurance from the therapist and the patient's family and friends are important components of therapy. (See also mental disorder: Conversion disorder (mental disorder).)