Hysteria, a psychoneurosis, in which unconscious emotional conflicts appear as severe mental dissociation or as physical symptoms (conversion reactions), is not dependent upon any known organic or structural pathology. The underlying anxiety is assumed to have been "converted" into a physical symptom.

The term is derived from the Greek hystéra, meaning "uterus". The "wandering of the uterus" theory reflects the ancient notion that the womb somehow became transplanted to different positions.

Therefore, hysteria was considered a specifically female disorder and was attributed to a malfunctioning uterus. Actually, hysterical symptoms may develop in either sex and are observed most commonly in early adult life.

At the end of the 19th century, Jean Martin Charcot (1825-1893), a leading French neurologist of his time, who used hypnosis to study hysteria, demonstrated that morbid ideas could produce physical manifestations. His pupil, the French psychologist Pierre Janet (1859-1947), emphasized the psychological rather than the physical causes of hysteria.

Later Sigmund Freud(1856-1939) began investigations with Breuer into the psychic mechanisms involved in hysteria and developed the theory that it was caused by repressed, emotionally charged memories.

Cases of classical hysteria, such as those frequently described by 19th-century clinicians, have become rare. Nowadays most psychoneuroses are apt to be "mixed" forms in which hysterical symptoms may be found interspersed with other varieties of neurotic disturbances.

The sensory and motor manifestations of hysteria are designated conversion reactions because the disturbances generally do not follow any anatomic distribution of the nervous system.

Sensory disturbances may:

• encompass the senses of vision, hearing, taste, or smell;
  
• range from peculiar sensations through hypersensitivity to complete anesthesias;
  
• 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. Loss of speech, coughing, nausea, vomiting, or hiccuping are at times hysterical in origin.