Tuesday, August 06, 2013

Melzack & Katz, Pain, Part 19: Implications of the Neuromatrix concept - phantom pain

The paper, Pain.

Part 18: Multiple determinants of pain


Whoo hoo! We are all the way to "Implications of the Neuromatrix concept."

1. Phantom Limb Pain:

Melzack and Katz say, 
"The neuromatrix theory of brain function, proposed largely on the basis of phantom limb phenomena, provides an explanation for phantom limb pain." 
Well, I don't know that I'd call it "explanatory" exactly..  I think some recent research better "explains" how this might all be possible, providing support for a neuromatrix model: but I think Melzack's neuromatrix model was a thoughtful careful reflective brilliant cognitive-evaluative leap into a previously mostly unknown void from the perspective of pain science, one it seemed quite clueless about, a lovely stretchy framework that caught pain science up to the rest of neuroscience, or at least provided a spacious perch from which he (and anyone who spent any time up and away from nociceptive input, learning about how our brains look after us and examining his model) could observe the rest of the pain research world start to catch up and fill in explanations that had been previously missing. 
I noted a few recent research un-coveries about the brain in this blogpost, Interlude: The non-monolithic brain: "You don't need a body to feel a body"- Melzack, from July 26, which I didn't include in the series, because it wasn't directly to do with the Melzack and Katz paper itself. But it is related.. At least I think so, so I'm including it now. 

More in this section:
"Amputees suffer burning, cramping, and other qualities of pain. A prospective study found that 72% of amputees had phantom limb pain one week after amputation, and that 60% had pain 6 months later.74 Fifty-five percent of amputees continue to suffer phantom limb pain a median of 50 years after amputation.75 Only about 10–12% of amputees obtain pain relief.74 The pain is remarkably intractable; although many forms of treatment have been tried, none has proved to be particularly efficacious."
"The active body-neuromatrix, in the absence of modulating inputs from the limbs or body, produces a neurosignature pattern, including the high-frequency, bursting pattern that typically follows deafferentation, which is transduced in the sentient neural hub into a hot or burning quality. The cramping pain, however, may be due to messages from the action-neuromodule to move muscles in order to produce movement. In the absence of the limbs, the messages to move the muscles become more frequent and ‘stronger’ in the attempt to move the limb. The end result of the output message may be felt as cramping muscle pain. Shooting pains may have a similar origin, in which action-neuromodules attempt to move the body and send out abnormal patterns that are felt as shooting pain. The origins of these pains, then, lie in the brain."

74 goes to Nikolajsen LJensen TS. Postamputation pain. In: Melzack RWall PD, eds. Handbook of Pain Management. Edinburgh: Churchill Livingstone; 2003247257.

75 goes to Wartan SWHamann WWedley JRMcColl I. Phantom pain and sensation among British veteran amputees. Brit J Anaest 1997,78:652659. (full access)

This is a short post. I refer you to early (and longer) posts in the series, for more about this, the story as it unfolded, as Melzack recalled his exploration of the literature on phantom limb pain and concluded that pain needed a new model. 

Part 9: Phantom pain - in the brain! 
Part 9b: Dawn of the Neuromatrix model 
Part 9cNeuromatrix: MORE than just spinal projection areas in thalamus and cortex 
Part 9d: More about phantom body pain in paraplegics

I'd say the implications of the neuromatrix concept are pretty good for helping people with phantom limb pain to cope, and evidence exists in the form of successful trials of mirror therapy. 


Previous blogposts

Part 1 First two sentences Part 2 Pain is personal Also Pain is Personal addendum., Neurotags! Pain is Personal, Always.

Part 3a Pain is more than sensation: Backdrop Part 3b Pain is not receptor stimulation Part 3c: Pain depends on everything ever experienced by an individual

Part 4: Pain is a multidimensional experience across time

Part 5: Pain and purpose

Part 6a: Descartes and his era; Part 6b: History of pain - what’s in “Ref 4”?; Part 6c: History of pain, Ref 4, cont.. : There is no pain matrix, only a neuromatrix; Part 6d: History of Pain: Final takedown Part 6e: Pattern theories in the history of pain Part 6f: Evaluation of pain theories Part 6g: History of Pain, the cautionary tale. Part 6h: Gate Control Theory.

Part 7: Gate control theory has stood the test of time: Patrick David Wall;  Part 7bGate control: "The theory was a leap of faith but it was right!"

Part 8: Beyond the gate: Self as mayor Part 8b: 3-ring circus of self Part 8c: Getting objective about subjectivity

Part 9: Phantom pain - in the brain! Part 9b: Dawn of the Neuromatrix model Part 9cNeuromatrix: MORE than just spinal projection areas in thalamus and cortex Part 9d: More about phantom body pain in paraplegics

Part 10: "We don't need a body to feel a body." Part 10b: Conclusion1: The brain generates its own experience of being in a body Part 10c:Conclusion 2: Your brain, not your body, tells you what you're feeling Part 10dConclusion 3: The brain's sense of "Self" can INclude missing parts, or EXclude actual parts, of the biological body Part 10eThe neural network that both comprises and moves "Self" is (only)modified by sensory experience

Part 11We need a new conceptual brain model! Part 11b: Intro to a new conceptual nervous system Part 11c: Older brain models just don't cut it Part 11d: The NEW brain model!

Part 12: Action! 12b: Examining the motor system, first pass. 12c: Motor output and nervous systems - where they EACH came from Part 12d... deeper and deeper into basal ganglia Part 12e: Still awfully deep in basal ganglia Part 12f: Surfacing out of basal ganglia Part 12gThe Action-Neuromatrix 

Part 13: Pain and Neuroplasticity Part 13b: Managing neuroplasticity

Part 14: Side trip out to the periphery! Part 14b: Prevention of pain neurotags is WAY easier than cure Part 14cPW Nathan was an interesting pain researcher  Part 14dBrain glia are from neuroectoderm and PNS glia are from neural crest Part 14e: The stars in our headsPart 14f: Gleeful about glia Part 14g: ERKs and MAPKs and pain Part 14h: glia-fication of nociceptive input 14i: molecular mediators large and small Part 14j: Neurons, calling glia (over, do you read?) Part 14k: Glia calling glia, over. Do you read? Part 14l: satellite cell and neuron cell body interactions, and we're outta here!

Part 15: Prevention of neurobiological hoarding behaviour by dorsal horn and DRG glia is easier than clutter-busting after the fact

Part 16: Apples are to fruit as cows are to animals as nociceptive input is to pain

Part 17: The stress of it all Part 17b: Stress and adrenals Part 17c: Women, pain, and stress Part 17d: Stress, aging, and pain Part 17e: Stress and aging, keeping hippocampal dendrites fluffed up Part 17f: Chrousos and Gold and stress Part 17g: Stress conceptualization through the agesPart 17h: Phenomenology and physiology of stress Part 17i: Pathophysiology of stress Part 17j: cortisol, good or bad? Sensitivity to pain traumatization.


Mark Hollis said...

I know that when a whole limb is taken away it's easy to understand phantom limb pain (I can see that you can see that some tissue is lost and yet you still have a schema of it neurally) ... however could this also be an avenue for explaining smaller losses of tissue in the body. I think of ACL ruptures or rotator cuff or scars in the skin or (from a more recent client) loss of tissue secondary to chemotherapy. The tissues gone, the visual representation may be present or changed (bruising/swelling),the somatosensory representation is still tagged, at a 'Wolpert -bayesian inference machine level there is still a mismatch between output and input that the brain perceives as nonbeneficial and threatening?

Diane Jacobs said...

Hi Mark, maybe.
The brain maps the space around the body, and the occupation of it by the body, too, so maybe there is some sort of discrepancy there too..
Anyway, I don't know, but I think it's a great question. Maybe some of the virtual space/rubber hand researchers would know.