Psychosomatic study on chronic pain. Clinical features of chronic pain and reconsideration on its definition

In the Department of Psychosomatic Medicine, Kyushu University, a chronic pain patient is defined on the basis of our clinical experiences and reviews of associated literatures as 'the patient whose pain complaint or social or occupational impairment is in excess of what would be expected from the underlying organic pathology'. We assessed the pathogenesis of each patient in this category based on a multidimensional evaluation including organic, functional and psychiatric diagnosis, as well as behavioral analysis and family analysis. In this paper, 40 cases who had been treated as having chronic pain on inpatient basis in our institute were studied regarding their clinical features. The results are as follows: 1) Before the first visit to us, they underwent various treatments at many institutes and several admissions. In addition, some cases underwent one or more operations for alleviation of the pain in vain. 2) An operation for a physical disease, a psychosocial stressor, an injury and a disease with no need of operation were considered to have functioned as the precipitating factor for the pain. Many patients developed their pain from an experience of a noxious stimulus as a trigger. 3) psychiatric diagnosis made according to DSM-III-R showed that conversion disorder and major depression were the two most common disorders and that a few cases had hypochondriasis or social phobia. These psychiatric disorders led to the pain of the patients. As accompanying psychiatric diseases, there existed psychoactive substance abuse, panic disorder, factitious disorder or others on Axis I and some kinds of personality disorder on Axis II. 4) As functional diseases, there were deafferentation pain, reflex sympathetic dystrophy, tension-type headache, irritable bowel syndrome, non-ulcer dyspepsia and aerophagia. 5) The comparison between the characteristics of depressive disorder and those of conversion disorder revealed that patients with depressive disorder were significantly more related to experience of a noxious stimulus. 6) Behavioral analysis suggested that operant learning mainly played a causative role in the pain behaviors of many cases. 7) In the operant pain patients, 4 types of consequence in their environment acted as reward contingent on their pain behaviors. These included solicitous response, avoidance of reality, avoidance of conflict and maintenance of family system. These results suggest that there exists a complicated pathogenesis consisting of various factors behind persistent and intractable pain. Therefore, it is necessary to evaluate chronic pain patients on the basis of detailed psychosomatic assessment. It is thus considered to be important to attempt to understand the psychological, social and existentional meanings of each patient's pain.