Chronic Pain: Evolution of Clinical Definitions and Implications for Practice

Numerous definitions of pain have been proposed over many years with different implications when applied to clinical practice. This paper reviews information regarding the evolution of definitions of pain terminology and pain syndromes as they relate to everyday practice for clinicians and those operating within the medicolegal judicial system, both trainees and seasoned professionals, with a focus on chronic pain. An historical overview of the evolution and chronology of chronic pain labels and definitions is provided with emphasis on those used currently in clinical practice. Subsequently, the paper mainly concentrates on the two more recent revisions of the Diagnostic and Statistical Manual of Mental Disorders (DSM) of the American Psychiatric Association (APA) and the basic principles of International Classification of Diseases (ICD) by the World Health Organization (WHO). It further provides a summary of the newly accepted WHO ICD-11 novel classification of pain disorders, a joint effort of WHO and the International Association for the Study of Pain (IASP). We conclude our review by providing our personal opinions and commentaries on controversies and dilemmas associated with the DSM, and ICD pain definitions and classifications, and offer useful tips for those who perform forensic examinations.