At the end of this session you will be able to:
1. Describe the key pathophysiological processes involved in pain
In addition you will be able to:
2. briefly outline the Gate-Control theory of pain
3. identify pain excitatory and pain modulating mechanisms
4. describe the role of substance
The pathophysiology of pain can be divided into three main processes: nociceptive, neuropathic, or idiopathic (see Table 4).
However, these processes are complex and interrelated.
| Table 4: The three main pain mechanisms (developed from AMA, 2003) |
| Nociceptive Pain | “Clinically, pain can be labeled “nociceptive” if it can be inferred that the pain is related to the degree of receptor stimulation by processes causing tissue injury. Nociceptive pain involves the normal activation of the nociceptive system by noxious stimuli”. |
| Neuropathic pain | “Neuropathic pain is the label applied to pain syndromes inferred to result from pathophysiologic changes in the peripheral or central nervous system (CNS). These changes may be caused by injury to either neural or non-neural tissues. Such pain becomes independent of the initial injury or damage, and sustains a chronic pain state.” |
| Psychological and ‘Idiopathic’ Pain | “The patient’s psychological state contributes significantly to complaints of pain and suffering and is fundamental to the subjective nature of pain and how well it is accepted. Symptoms and their associated distress are real to the patient, independent of the degree to which psychological factors are involved. In some cases, evidence that the pain itself is sustained by psychological factors can be inferred. This phenomenon is known generically as “psychogenic” pain”. |
