PAIN-PHYSIOLOGY

SUMMARY

1. Pain conduction can be described by 4 processes: transduction, transmission, modulation, and perception.

2. Afferent activity induced by peripheral injury triggered a long-lasting increase in the excitability of spinal cord neurons, profoundly changing the gain of the somatosensory system.

3. Central sensitization: activity-dependent synaptic plasticity in the spinal cord that generates post-injury pain hypersensitivity, hyperalgesia & allodynia.

4. This central facilitation manifested as:
- Allodynia: reduction in threshold
- Hyperalgesia: increase in responsiveness and prolonged aftereffects to noxious stimuli
- Secondary hyperalgesia: receptive field expansion that enabled input from non-injured tissue to produce pain

Reference(s)

Woolf C.J. (2011). Central sensitization: Implications for the diagnosis and treatment of pain. Pain. 2011 March ; 152(3 Suppl): S2–15. doi:10.1016/j.pain.2010.09.030.

Cifu, D.X. (2020). Braddom’s physical medicine and rehabilitation. Elsevier. Get it on Amazon.
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O’Young, B., Young, M.A. and Stiens, S.A. (2008). Physical Medicine and Rehabilitation Secrets. Mosby. Get it on Amazon.