Chronic pain: Encyclopedia - Chronic pain

Chronic pain

Chronic pain was originally defined as pain that has lasted 6 months or longer. It is now defined as pain that persists longer than the normal course of time associated with a particular type of injury. This constant or intermittent pain has often outlived its purpose, as it does not help the body to prevent injury. It is often more difficult to treat than acute pain. Expert physician care is generally necessary to treat any pain that has become chronic. When opioids are used for prolonged periods drug tolerance, chemical dependency and even psychological addiction may occur. Chemical dependency is common among opioid users; however, psychological addiction is less frequent. Apparent drug tolerance to the pain-relieving effects of opioids may occur. This may be confused with progression of the underlying disease in cancer patients rather than an actual decrease in efficacy of the drug.

Chronic pain - Causes

Chronic pain is essentially caused by the bombardment of the central nervous system (CNS) with nociceptive impulses, which causes changes in the neural response. The pain subsequently provokes changes in the behavior of the patient, and the development of fear-avoidance strategies. As a result, the patient may also become physically atrophied and deconditioned. However, it is important to remember that chronic pain is multifactorial, with the underlying biological changes affecting physical and psychosocial factors.

In 2005, University of Toronto researcher Min Zhuo established a connection between chronic pain and the NR2B protein.[1]

Chronic pain - Types

There are various types of chronic pain- malignant and non-malignant. Cancer pain can be from the cancer itself and from treatment. Non-malignant pain includes arthrtitis, neuropathy/neuralgia, back pain from injury or disorders (cervical stenosis, degenerative disc disease, other disc disorders, etc), migraines and other types of headaches, abdominal pain from chronic pancreatitis, bowel disorders, etc; pelvic pain from various conditions (endometriosis, interstitial cystitis, etc); and also diffuse conditions such as fibromyalgia, reflex sympathetic dystrophy, lupus and other systemic autoimmune/connective tissue conditions, multiple sclerosis and some other neuromuscular conditions. Chronic pain basically can be anywhere in the body, this is just a list of some of the conditions that affect people long term (usually longer than 6 months).

Adapted from the Wikipedia article "Chronic pain", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki