Chronic Pain

Chronic pain (pain persisting beyond expected tissue healing time, typically >3 months) involves fundamental neuroplastic changes that transform pain from a symptom into a disease state. At the molecular level: peripheral sensitization (reduced nociceptor thresholds, ectopic discharge), central sensitization (NMDA receptor-mediated wind-up, expanded receptive fields in the dorsal horn, loss of inhibitory interneurons through apoptosis), descending modulation dysfunction (shift from inhibitory to facilitatory output from the rostral ventromedial medulla), and cortical reorganization (somatotopic map changes, prefrontal cortex gray matter loss, amplified activity in the pain neuromatrix including anterior cingulate cortex, insula, and thalamus). The biopsychosocial model recognizes that chronic pain is not simply a biological phenomenon but an experience shaped by psychological factors (catastrophizing, fear-avoidance, depression, anxiety, self-efficacy) and social factors (work disability, social isolation, litigation, cultural beliefs about pain). Treatment failure in chronic pain often results from addressing only the biological component while ignoring the equally important psychological and social dimensions. Comprehensive assessment using validated tools is essential for identifying all contributing factors and developing an individualized management plan.