By far the most important psychogenic categories are the fourth and fifth groups, hysterical disorders and psychosomatic disorders. Hysterical disorders are mostly of historical interest, although the psychology of both is identical. My experience has been primarily with psychosomatic disorders.
The symptoms of hysterical disorders are often quite bizarre. The patient may experience a wide variety of highly debilitating maladies, including muscle weakness or paralysis, feelings of numbness or tingling, total absence of sensation, blindness, inability to use their vocal cords, and many others, all without any physical abnormalities in the body to account for such symptoms.
It is clear from the nature of hysterical symptoms that their origin is indeed “all in the head,” to take a pejorative phrase commonly used to refer to psychosomatic symptoms. The absence of any physical change to the body indicates that the symptoms are generated by powerful emotions in the brain. Just where in the brain, no one can say for sure. One medical authority, Dr. Antonio R. Damasio, has suggested that these emotion-generating centers are located in the hypothalamus, amygdala, basal forebrain, and brain stem. The patients perceive symptoms as though they were originating in the body when the appropriate brain cells are stimulated. These symptoms often have a very strange and unreal quality about them. One of the nineteenth-century pioneers of psychiatry, Josef Breuer, likened them to hallucinations.
