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.
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.