Common acute pain is the result of burns, broken bones, or other injury. The treatment of acute temporal pain involves the interruption of a continuous flow of pain messages sent from the damaged nerve endings to the brain. If treatment is not initiated quickly enough, acute pain may develop into chronic pain. Pain is defined as chronic if it has not abated by six months after the initial injury has healed and if there has been no response to pain therapy. Chronic pain, which by definition resists treatment, can lead to functional loss, social withdrawal, depression, thoughts of suicide, and other severe changes in mood and behavior.
Etiologic pain can be either malignant or nonmalignant and is almost always chronic.
Malignant pain is often the symptom of larger illnesses, including AIDS, cancer, amyotrophic lateral sclerosis, and multiple sclerosis. Such pain has been linked to a decrease in expected lifespan. Nonmalignant pain does not reduce life expectancy. Chronic, nonmalignant pain includes such conditions as arthritis, skin ulcerations, tension headaches, and poststroke pain. It also includes painful disorders with a psychological basis, such as hysterical reactions, and pain originating from an indeterminate pathophysiology, including recurrent migraine headaches and vasculopathic pain syndromes.