Modern concepts of chronic pain

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or similar to such an experience. The classification of chronic pain (ICD-11) includes chronic primary pain; chronic secondary pain; chronic pain associated with cancer; chronic postoperative or post-traumatic pain; chronic neuropathic pain; chronic secondary headache or orofacial pain; chronic secondary visceral pain; chronic secondary musculoskeletal pain. A modern understanding of the mechanisms of chronic pain development highlights neuroplastic factors (including central sensitization, peripheral sensitization, and descending neuromodulation). It has been proven that pain leads to functional changes in brain neural networks; cognitive and memory abnormalities are detected in patients with chronic pain when undergoing neuropsychological tests. Predictors of chronic pain syndrome development include non-modifiable characteristics, individual psychological characteristics, including mental illness, social factors, and comorbidities. Existing pain assessment methods include patient self-assessment, physician-based pain assessment, and pain assessment based on biological indicators. However, there is still no "gold standard" for pain diagnosis, as none of these methods are fully reliable, universal, or easy to use.