Lila Squad,
I'm not sure I have this clear in my head yet but I can't sleep and I
need some diversion.
The Sep 21 issue of the New Yorker magazine has an article in it
regarding some research on pain that has been going on lately. The author
is an MD pain specialist who says that violent pain, convulsions, and the
like without an identifiable organic cause are extremely common today. In
fact he says :
"Chronic back pain is now second only to the common cold as a cause of
lost work time, and it accounts for some forty percent of workers
compensation payments. In fact there is a veritable epidemic of back pain
in this country and nobody can explain why."
According to the author the traditional explanation of pain originated
with Rene Descartes. Descartes proposed that pain is a purely physical
phenomenon-that tissue injury stimulates specific nerves that transmit an
impulse to the brain, causing the mind to perceive pain. Twentieth century
research on pain has been largely devoted to the discovery of pain specific
nerve fibers.
The limitations of this mechanistic view of pain has been apparent for
some time.
During WW2 a Col Beecher conducted a study of men with serious
battlefield injuries. He found that 58% of the men with gunshot wounds,
compound fractures, torn limbs, reported only slight pain or no pain at
all. Just 27% of the men felt enough pain to request pain medication.
Col Beecher thought the reason might be that the men were overjoyed to
have escaped alive from the battlefield and that this counteracted the
signals sent by their injuries.
In 1965 the Canadian Ronald Melzak and the Briton Patrick Wall proposed a
gate control theory of pain. They said that before pain signals reach the
brain they must go through a gating mechanism in the spinal cord which
could ratchet them up or down, or in some cases, simply stop the pain. The
dorsal horn of the spinal cord was identified as the pain gate.
Melzack and Wall also suggested that in addition to signals from sensory
nerves that emotions and other output from the brain could control the pain
gate. They were saying that the mind itself could stop pain.
Research bore out the idea that the mind could control awareness of pain.
Today every medical textbook teaches the gate control theory as fact. It
accepts Descartes theory that what you feel as pain is a signal transmitted
by nerves to the brain, and it adds the notion that the brain controls a
gateway for such an injury signal.
The trouble with this theory is that it doesn't explain the large number
of people who experience violent pain with no apparent cause, nor does it
explain phantom limb pain.
In 1994 a Dr. Lenz was operating on a patient for an uncontrollable
tremor.in which the object was to destroy cells in a small structure called
the thalamus which was known to contribute to stimulation of the hands.
It happened that this patient also had a panic disorder problem in which
he would suffer severe chest pains as if he were having a heart attack
This operation is done with the patient awake. Making a hole in the skull
the surgeon inserted a probe, stimulated the thalamus at the tremor site,
and got a mild tingling in the forearm as expected. To be sure of his
location he stimulated an adjacent site which normally gives a mild
sensation in the chest. In this case the result he got was a violent panic
attack with severe chest pain, sensation of suffocation, and fear. Removing
the stimulation the symptoms disappeared. When he tried again he got the
same result. Lenz recalled that he had had a similar experience with a
woman he had previously operated on. In these two patients the response was
wildly out of proportion to the stimulus.
In the case of the woman he concluded that the heart condition had
abnormally sensitized that area of the brain.
In the case of the man he concluded that the panic disorder had
abnormally sensitized that area of the brain and was associated not with
any bodily damage but with the man's abnormal psychology.
Lenz's findings suggest that all pain is in the head and that sometimes a
physical condition is not necessary to make the pain system go haywire.
The gate control system of pain as the result of nerve damage is still
viable except that now the damaged nerve produces nerve signals that travel
through the spinal cord gate but it is the brain that produces the pain
experience.
According to the new theory pain and other sensations are conceived as
"neuromodules" in the brain and that when you feel pain it is your brain
running a neuromodule that produces the pain experience. It is said that a
neuromodule is not a discrete anatomical entity but a network linking
components from every region of the brain.
"Input is gathered from sensory nerves, memory, mood, and other centers,
like members of some committee...If the signals reach a certain threshold
they trigger the neuromodule. And then what plays is no one-note melody.
Pain is a symphony-a complex response that includes not just a distinct
sensation, but also motor activity, a change in emotion, a focussing of
attention, a brand new memory."
A stubbed toe signal still has to make it through the pain gate, but then
it joins a lot of other signals in the brain, distractions, memories,
anticipation, mood, etc. Generally they combine to activate a toe pain
module. In some people the stimulus is cancelled out and the toe pain is
hardly noticed.. However, the same neuromodule can go off generating
genuine toe pain without the toe having been stubbed. The neuromodule could
become primed like a hair trigger then virtually anything could set it off:
a mere touch, fear, frustration, or simply a memory. Pain specialists
increasingly prescribe anti-epileptic drugs for their most difficult
patients. The lesson is that the pain antecedents lie elsewhere than in
muscle and bone.
Some forms of chronic pain have become social epidemics.
Before the advent of HMOs (health maintenance organizations, privately
owned profit making organizations which prescribe how much time a physician
can spend with a patient as well as other restrictions on Doctors
activities) there was a very low incidence of back pain complaints among
physicians. With the decrease in job satisfaction that accompanied the HMOs
the incidence of back pain among surgeons who had to work long hours in
awkward positions over operating tables became almost epidemic.
In Australia, a job related injury among keyboard operators that became
labeled RSI (repetitive strain injury) resulted in severe, disabling, arm
pain.
Before 1981 this injury hardly existed. When it was identified as RSI and
given recognition status it grew to epidemic proportions. In two Australian
states RSI disabled as much as thirty percent of the work force. At the
same time there were pockets of workers who were hardly affected. Clusters
appeared even within a single organization and varied widely between
departments. In most cases no somatic cause could be identified.
Then, as suddenly as it had appeared, the epidemic crashed. By 1987 it
was essentially over.
These epidemics demonstrate the power of cultural factors to cause
genuine, disabling pain on a national scale. Pain has acquired a political
and cultural aspect.
All of this suggests that if we could isolate the brain from the body and
still have it perform all of its normal functions that we could experience
all forms of bodily pain.
I thought that these ideas might add a new perspective to some of the
discussions that are now going on within the squad. Ken Clark.
homepage - http://www.moq.org
queries - mailto:moq@moq.org
unsubscribe - mailto:majordomo@moq.org with UNSUBSCRIBE MOQ_DISCUSS in
body of email
This archive was generated by hypermail 2b30 : Sat Aug 17 2002 - 16:02:34 BST