[fmichael]

In response to a thread Sandra posted the other day, Roz posted the most intriguing stub article from Wikipedia. Here it is in full text:

Hyperalgesia

From Wikipedia, the free encyclopedia

Hyperalgesia is an extreme sensitivity to pain, which in one form is caused by damage to nociceptors in the body's soft tissues.

Hyperalgesia can be experienced in focal, discrete areas, or as a more diffuse, body-wide form. Conditioning studies have established that it is possible to experience a learned hyperalgesia of the latter, diffuse form. The focal form is typically associated with injury, and is divided into two subtypes:

Primary hyperalgesia describes pain sensitivity that occurs directly in the damaged tissues.
Secondary hyperalgesia describes pain sensitivity that occurs in surrounding undamaged tissues.

Hyperalgesia is induced by Platelet Aggregating Factor (PAF) which comes about in an inflammatory or an allergic response. This seems to occur via immune cells interacting with the peripheral nervous system and releasing pain-producing chemicals (cytokines and chemokines) (see Marchand, Perretti, & McMahon, 2005).

One unusual cause of focal hyperalgesia is platypus venom.

Ikeda, Stark, Fischer, Wagner, Drdla, Jäger, et al. (2006) showed that stimulation of pain fibres in a pattern consistent with that from inflammation switched on a form of amplification in the spinal cord, long term potentiation. This occurred where the pain fibres contacted a pain pathway, the periaqueductal grey. Ikeda et al. argued that amplification in the spinal cord is another way of producing hyperalgesia.

References
Ikeda, H., Stark, J., Fischer, H., Wagner, M., Drdla, R., Jäger, T., et al. (2006). Synaptic amplifier of inflammatory pain in the spinal dorsal horn. Science, 312, 1659-1662.

Marchand, F., Perretti, M., & McMahon, S. B. (2005). Role of the immune system in chronic pain. Nature Reviews Neuroscience, 6, 521-532.

Since then, a friend of mine was nice enough to send me the two referenced articles, which are both very good. But the piece by Marchand, Perrett and McMahon, "Role of the Immune System in Chronic Pain" - in particular - is just this absolutely jaw-dropping review article that I cannot recommend highly enough.

The two articles also directly complement the outstanding piece from the December 20, 2006 issue of PainOnline.com on NMDA in central pain that Hope - as in HopeLivesHere - was also kind enough bring to my attention earlier this week. http://neurotalk.psychcentral.com/sh...hlight=Michael/ http://www.painonline.com/mt-archive...it_togeth.html

I will be happy to send copies to anyone who wants either or both of them, just send me a pm with your email address, as both are too big to attach here. Be well all.

Mike

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