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Peripheral mechanisms of somatic pain
S N Raja1, R A Meyer, J N Campbell
1Department of Anesthesiology and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
Anesthesiology
|April 1, 1988
Summary
Advances in pain mechanisms reveal nociceptors signal pain. Inflammation causes hyperalgesia via nociceptor sensitization, but chronic pain mechanisms remain unclear.
Area of Science:
- Neuroscience
- Pain Research
- Physiology
Background:
- Significant progress in understanding pain mechanisms over the last two decades.
- Evidence supports specific nociceptors and neural pathways for pain signaling in normal skin.
- Nociceptive afferents from skin, muscle, and joints are key to pain sensation.
Purpose of the Study:
- To review current understanding of pain mechanisms, focusing on nociceptors and hyperalgesia.
- To explore the roles of chemical mediators and neuropeptides in pain sensitization.
- To highlight the gaps in knowledge regarding chronic pain pathophysiology.
Main Methods:
- Correlating subjective pain estimates with nerve fiber activity in animals and humans.
- Microneurographic recordings in awake humans.
- Review of studies on cutaneous and articular afferent properties.
Main Results:
- Nociceptor sensitization explains primary hyperalgesia due to inflammation, involving arachidonic acid metabolites and bradykinin.
- Changes in articular afferents may explain arthritis pain; substance P is implicated.
- Secondary hyperalgesia mechanisms are less understood, involving peripheral and central nervous system changes.
Conclusions:
- While acute pain mechanisms are increasingly understood, chronic pain pathophysiology requires further investigation.
- Future research combining animal studies, psychophysics, and microneurography in patients is crucial.
- A deeper understanding of pain mechanisms is essential for addressing chronic pain conditions.