Psychosomatic disorders , also called somatoform disorders, are physical conditions with symptoms (or perceived symptoms) that are manifestations of psychological distress. These manifestations are identical to its corresponding physiological disorder. A person with a psychosomatic disorder may, for example, experience frequent headaches and be improperly diagnosed with a headache disorder. Indeed, the person suffers from a deeper issue: a psychiatric disorder. This is determined by the health team after all possible organic causes have been eliminated. Psychosomatic disorders may be physical manifestations of anxiety and mood disorders, and especially of stress disorders following psychological trauma.
The Amercian Psychiatric Association's fourth (text-revised) Diagnostic and Statistical Manual of Mental Disorders (DSM-IV TR), lists criteria for the diagnosis of such a disorder. The criteria are the presence of physical distress (e.g. headache, siezure, gastrointestinal pain, etc.) and that after intensive and sufficient medical investigation, no organic cause is found. The physical presentations must not be due to any external substance such as illicit drugs and abuse of prescription medication. The symptoms must be severe enough to caused marked distress or impairment in normal functioning. The duration of the disorder must bee or have been at least six months and without being intentionally produced. And of course, the symptoms must not be accounted for by any other psychiatric disorder (DSM-IV TR, p. 492).
Anthony Feinstein (2011) authored a review on the latest research on conversion disorder and the role of neurobiology. In the review, Dr. Feinstein points out that, in brain imaging studies, those with conversion disorder vibratory stimulus to a subject's "paralyzed" limb, normally active brain areas in stimulation to the arm were not active on the side of the brain controlling that arm. Instead, the frontmost areas of the brain were active (the areas controlling anxiety and mood). This type of paralysis is a physical manifestation of psychological distress and not permanent.
It is possible that neurodevelopmental or neuroembryological processes have influence here.
In those who suffer from post traumatic stress disorder, perhaps the physical symptoms may be inevitably learned.