Definition of pain and classification of pain disorders

Pain of any origin comprises an individual’s life. The prevention and management of pain is an important aspect of health care. Psychological factors play a key role in both onset and progress of any pain disorder. In pain disorders, pain is perceived in different anatomic locations such as lower back, head region, abdomen, and chest. Abnormal signal transmission and processing in the nervous system are the legitimate explanation for this condition. Although evidence suggests that pain disorder is widely prevalent in the general population, research still fails to address numerous aspects of pain diagnosis and management. Diagnostic criteria for pain differ in various Diagnostic and Statistical Manual of Mental Disorders (DSM) such as DSM-III, DSM-III revised, DSM-IV, and DSM-IV-textual revisions; hence, a more comprehensive classification is the need of the hour. The ability to understand and investigate the pathophysiologic process underlying a disorder depends on a valid, reliable classification system and common terminology to make effective communication among the academicians, clinicians, researchers, and patients. After the classification criteria are achieved, the validity and reliability of the criteria must be analyzed. Once the criteria have proven valid and reliable, research effort can be directed toward gaining better insight into prevalence, etiology, and natural course of a given disorder, eventually leading to more effective treatment. In this review, various definitions of pain along with few diagnostic classification systems for various pain disorders have been presented.