Chronic pain is a problem that affects the patients quality of life to a variable but in some cases, extreme degree. Cause The exact final cause of pain has yet to be discovered. Some of the mechanisms of pain causation and pain relief have been identified. One of the most important discoveries has been the presence of chemicals within the nervous system called endorphins. These chemicals act as an internal narcotic medication, decreasing pain.
Many diseases can cause chronic pain.
Of course, this can only be a partial list. The obvious symptom of chronic is persistent pain. It may be mild, moderate or severe. It may be intermittent or constant. The important factors are that it is present and that it has been around for a long time.