National Consensus on Diagnosis and Treatment of Pain from Neurological Disorders
Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage.
By its duration pain is classified as acute and chronic. Acute pain is a symptom, chronic pain is a disease.
Acute pain is related to clearly identified tissue injury and lasts no more than 1 month from its onset. It is protective and gradually resolves as the injured tissues heal, when the environment surrounding the nociceptors is normalized and their hyperactivity resolved.
Chronic pain persists for more than 3 months. It is caused by tissue damage but continues even after the causative lesion heals. It is not due to activation of nociceptors and has no protective effect.
According to the underlying pathophysiological mechanisms pain is classified as nociceptive or neuropathic. The combination of both types (mixed) pain is common.
According to its anatomical location pain is classified as head, face and mouth pain; cervical pain; pain in shoulders and arms; thoracic; abdominal; lumbar pain; pain in lower limbs; pelvic; anal, perianal and genital pain.
It is caused by injury to any organ or system other than the nervous system, and its diagnosis and treatment is associated with a number of medical specialties. It is subdivided into physiological nociceptive pain, caused by temporary dysfunction (cramps, colics), and pathological nociceptive pain, caused by tissue injury.
It is pain caused by dysfunction, lesion or disease directly affecting the somatosensory nervous system.