Chronic pain is a disease of the central nervous system. It is defined as “pain without apparent biological value that has persisted beyond normal tissue healing time” It is also defined as pain that either persists beyond the point that healing would be expected to be complete (usually taken as 3-6 months) or that occurs in disease processes in which healing does not take place. The pain may be continuous or intermittent. Chronic pain can be experienced by those who do not have evidence of tissue damage or biological reason for pain (International Association for the Study of Pain, 2007). This ‘unknown cause’ factor often results in difficulty in reaching a diagnosis.This type of pain can be nociceptive, or can be neuropathic i.e. handled by a dysfunctional nerve or cluster of nerve signals. People living with chronic pain often report hyperalgesia (increased sensitivity to pain), allodynia (heightened pain response to usually non-painful stimuli) or dysaesthesia (unpleasant abnormal sensations). Chronic pain can also arise from other types of pain.
Types of Pain
Pain can be classified by the type of pain or by body region. Classification by pain types includes:
Neuropathic pain: burning, stabbing, tingling, insect crawling, shooting, associated with allodynia, hypersensitivity or other sensory changes.
Nociceptive pain: aching, boring, worse on movement, anatomically defined, fluctuates in severity.
Mixed i.e. a combination of both neuropathic & nociceptive pain symptoms.
Visceral pain: dull, diffuse, ill-defined.
Autonomic symptoms: colour and temperature changes, sweating, trophic changes.