Somatic or "medically unexplained" symptoms and syndromes are common and are seen by physicians across almost every medical specialty. In many instances, these phenomena can cause a great deal of pain and frustration, restrict function and reduce patients' quality of life. Despite their frequency and severity, medical personnel often experience a great deal of difficulty in coping with such complaints and patients may be shuttled from specialist to specialist, often with little or no symptomatic relief and at a great deal of expense to the medical system. Many researchers now believe that these seemingly unrelated and "unexplained" conditions in fact share common psycho-physiological mechanisms, such as being catalyzed as a result of trauma or excessive stress, being mediated by the limbic system and affecting inhibitory sensory pathways.