Friday, June 21, 2013

Melzack & Katz, Pain. Part 9c: Neuromatrix: MORE than just spinal projection areas in thalamus and cortex

The paper, Pain

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

MORE than just spinal projection areas in thalamus and cortex

From the paper, in the section, Phantom Limbs and the Concept of a Neuromatrix, second paragraph:
"Note that we mean more than the spinal projection areas in the thalamus and cortex. These areas are important, of course, but they are only part of the neural processes that underlie perception. The cortex, Gybels and Tasker made amply clear, is not the pain center and neither is the thalamus. 20 The areas of the brain involved in pain experience and behavior must include somatosensory projections as well as the limbic system. Furthermore, cognitive processes are known to involve widespread areas of the brain. Despite this increased knowledge, we do not have yet an adequate theory of how the brain works."

Link 20 goes to Gybels JMTasker RR. Central neurosurgery. In: Wall PDMelzack R, eds. Textbook of Pain. Edinburgh: Churchill Livingstone; 1999,13071339.

It just so happens, I obsessively kept, packed and brought my 1999 4th edition of Textbook of Pain with me, when I moved 4 years ago. There are some things you just don't want to have to leave behind.
It was ten pounds of my life I couldn't afford to lose. I also brought the 5th edition. Another ten pounds. 

Anyway, I will meander into it and tell you what it has to say. Sounds like whatever in there is still important to Melzack, at least. 

Jan M. Gybels 

Jan M. Gybels is or was part of the Belgian Pain Society, it would appear. Here is a link to a few pictures I googled up. 
SOURCE:  Jan M GybelsBjörn Meyereson, Patrick Wall, 1991

He wrote a text about how to operate on the brain, Neurosurgical Treatment of Persistent Pain: Physiological and Pathological Mechanisms of Human Pain (Pain and Headache), back in 1989. It looks as though it was a one-edition text. Here is the one and only review it received. 

I can't find out anything else about this man. Not with Google, anyway.. 

Ronald R Tasker
Ron R. Tasker

Google can't come up with much else here, either. 

These two did all that hard work long before the internet was readily available. I'm guessing they probably retired long ago. Took their dogs out of the fight. 

I expect that if neurosurgeons of their apparent quality couldn't chop pain out of the brain - physically - no one ever could, or likely will. 

Their chapter in Textbook of Pain
Chapter 57, Central Neurosurgery, starts on p. 1307 of the 1999 4th edition. I'll bring bits here I think are relevant to the discussion, like the first part of the intro.
"It is now 50 years since the birth of stereotactic surgery and 35 years since the first percutaneous cordotomy. Over this time an extensive literature has accumulated dealing with the usefulness of destructive lesions in the central nervous system for the relief of chronic pain. However, much of these data are of questionable value in, firstly, assessing the efficacy of these procedures themselves and, secondly, comparing them with other pain treatment modalities." 

Wow. Right there. Refreshingly honest. 
Then they take a stand:
"It is the authors' opinion that it is time for a change in the way we document outcomes for all pain treatment strategies. Not only do we need to answer specific questions - Does destructive surgery for pain relief still have a role? Is the current virtual replacement of such destructive procedures by modulatory and non-surgical strategies preferable?  - but we must look ahead, in a general way... we must enter the realm of evidence-based practice."
Wow. To think they hadn't been using evidence-based practice all along
But apparently not. A bit later:
"There is no generally agreed upon method for measuring pain.. pain surgery may reduce but rarely abolish pain. Pain gradually returns after surgery (Tasker 1994)."
This is an unpleasant meander, through about 30 pages of descriptions of destructive surgeries done for pain, in hopes they would help, not knowing if they would, usually not helping. It's like a walk through an old battleground, years later, grassy knolls and filled-in foxholes marked by monuments that include old-timey photos of once-alive soldiers caked with mud and gore, faces etched by fatigue, agony, terror. 

Cordotomies. Cordectomies. Myelotomies. Mostly done for pain following cancer invasion of the lumbosacral plexus or pain after a brachial plexus avulsion (relatively common motorcyclist injury). Brain surgeries. Bulbar trigeminal tractectomy and nucleotomy. Bulbar and pontine spinothalamic tractectomy. Strereotactic mesencephalic tractotomy and thalamotomy. Medial thalamotomy. Gamma-knife medial thalamotomy. Basal thalamotomy. Pulvinarotomy. Hypothalamotomy. Pituitary ablation. For the telencephalon: Pre- and post central gyrectomy. Limbic surgery. Cingulotomy.
Most of the procedures are named after the surgeon who invented it. Each procedure has a lineage in the medical literature, a parade of names of dead white men, dating back to - you guessed it - the early 20th century and labelled-line theory. 

On Wikipedia's "History of Surgery" page, we see this: 
"Ambroise Paré, a 16th-century French surgeon, stated that to perform surgery is: "To eliminate that which is superfluous, restore that which has been dislocated, separate that which has been united, join that which has been divided and repair the defects of nature."
Hubris. "Repair the defects of nature"... 
Sure - up to a point. Taking out a space-occupying tumour? Sure. But remove functioning bits to try to cure pain? Not so much. 
There will be no end to attempts to "repair" people surgically, but until such time as entire neurotags can be identified that are restricted to only "pain", then safely ablated from the remainder of the brain with no harm to the rest of it, I just don't see the attraction of trying to surgically reduce pain by destroying actual bits of brain.  It's like removing parts of a computer to see if it will work better. Or something. How can it possibly help? How could anyone have possibly thought it would help? 
SOURCE: Lorimer Moseley

Given access to enough financial resources, humans can build huge conceptual edifices and institutional edifices on little more than wishful thinking, e..g., a surgical tradition of destroying parts of the CNS built upon nothing more than labelled line theory. If they don't have the financial resources at hand, and they have enough power, usually they will just take some from somebody else. These are commonly known as "taxes." 
But, enough mourning for all the human suffering that has gone on both pre-and post-willful destruction of central nervous system tissue. 
Here is what Melzack says the neuromatrix is:  
"Now let me make it clear that I mean more than just the sensory thalamus and cortex. These are important, of course, but they mark just the beginning of the neural activities that underlie perception. The cortex, White and Sweet have made amply clear, is not the pain center, and neither is the thalamus. The areas of the brain involved in pain experience and behavior are very extensive. They must include the limbic system as well as somatosensory projections. Furthermore, because our body perceptions include visual and vestibular mechanisms as well as cognitive processes, widespread areas of the brain must be involved in pain. Yet the plain fact is that we do not have an adequate theory of how the brain works."
From Ronald Melzack; Pain and the Neuromatrix in the BrainJournal of Dental Education. 2001 Volume 65, No. 12. Open access. 

I like that last sentence. It appears repeatedly in Melzack's writings. He reminds me of an art teacher I had, way back in my twenties, when I went to art school for a few years. He taught painting. He said, don't focus in on any one tiny area, finish that, then move to another small area. Stand back and make all the parts of the painting relate to all the other parts of the painting. Keep the painting open

Melzack is saying, don't commit to one pain theory over another. Nobody knows how the brain works, so let's just stand back and wait awhile. Let's start by not doing any harm. 

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