Pain disorder 

Persistent somatoform pain disorder is an ICD-10 diagnosis, which is included in the group of somatoform disorders. The term pain disorder is used in DSM-IV, and for convenience that is the term used here to refer to both classifications, unless a distinction needs to be made. This chapter aims to clarify the relationship of pain to mental disorders, the diagnosis of pain disorder and its differential diagnosis, and then considers how psychosocial factors contribute to pain, the treatments that stem from them, and the psychiatrist's potential contribution. Pain has been defined by the International Association for the Study of Pain (IASP) as ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage’. ‘Pain’ is used here in this sense; it is not used primarily to indicate mental distress or anguish. As a perception, pain is essentially a subjective experience, and is directly accessible only to the patient. By contrast, tissue damage can be assessed by others, and its relationship with the subjective characteristics of pain have been shown to be variable, modulated by social and cultural experience, as well as within the central and peripheral nervous system.