Chapter
One
Pain
The Nature Of Pain
What is
this thing called pain? It causes endless suffering, alters lives, frustrates
health care providers, and costs untold billions of dollars in medical
procedures, pills, and time lost from work. Despite the great advances in
medical science out efforts to control chronic pain and suffering produce
severe physical, social and emotional consequences.
Pain is
one of the essential bodily sensations. Without the ability to feel pain it
would be difficult to survive. In rare cases where children are born without a
thalamus, that portion of the brain that experiences pain is missing, therefore
burns and injuries occur more freely. The children succumb ultimately to the
complications from the injuries resulting from this disorder. Thus there is a
very useful function for pain.
As an
example, if you stumble out of bed in the Middle of the night and bump your toe
you experience pain.
The
pain impulse travels up the nerves of the leg and the spinal cord to the
thalamus where you experience pain, however, at this point you know only that
you have hurt yourself but not were. Beyond the thalamus the impulse travels to
the top of the brain. Here, in a part known as the sensory area of the cerebral
cortex, there is a map of the body sometimes called the homonculus or
"little person". This identifies that you have an injured toe. You
then reach down and rub the skin of your toe. This is "pain
behavior". The pleasant massage from the skin turns on some different sensory
nerves. The impulse travels into the nervous system and turns on that part that
controls pain. The pain goes away. That is an example of "useful
pain".
In
addition to this "useful pain" experience there is "useless
pain". If despite continuing massage of the toe the pain continues, day
after day and week after week and yet the doctors and x-rays can find no cause,
you then experience "useless" or chronic pain. In this instance the
second portion of the pain nervous system, the part that turns off pain, has
not worked properly. Thus, along with a part of the nervous system that allows
you to experience pain, the second part of this system modulates or turns off
the pain sensation.
You can
turn on that part of the nervous system that controls pain by stimulating a
body part such as your thumb. The electrical stimulus then travels very rapidly
from your thumb to your little persons thumb in your brain, at about seven
hundred miles per hour. This is about the speed of sound or one thousandth of a
second. For all practical purposes the two areas are stimulated
instantaneously. This stimulus in the brain then turns off the chronic pain.
Were
this not so we would be in misery all of our lives; hardly a day goes by that
you do not experience some pain sensation, minor though it may be.
A group
of neuropeptides activates this second anti-pain part of the nervous system.
This group includes endorphins, enkephalins, and dynorphins. Dr. Bruce Pomeranz
of Toronto, Canada, bred a strain of rats in which those chemicals responsible
for the modulation of pain were deficient. The rats when stimulated
electrically to overcome experimental pain, were not able to release into their
nervous system enough neuropeptides to control induced pain.
Pain
and the Nervous System
To
understand the workings of the nervous system it is basic to realise that the
nerve cells do not conduct nervous impulses as though they were continuous
wires. Synapses are the minute spaces between nerve cells. The nervous impulse
must cross this space to communicate from one cell to another. Certain
chemicals called neuro-regulators control the ability of nervous impulses to
cross this space.
There
are two types of such neuro-regulators, the neuro-transmitters that carry the
information forward and the neuro-modulators that either amplify or dampen the
message.
The
discovery of the opioid recepter sites on nerve cells was important for an
understanding of how pain is regulated. These receptors are binding sites on
the membrane of cells for endorphins and morphine. There are at least four
members in the endorphin family important for pain. These are Beta-endorphin,
methionine, and leucine enkephalin, and dynorphin. These are known as opiate
agonists as they activate morphine receptors in the fashion of opium or
morphine. Opiate antagonists are substances that block morphine receptors and
thus increase pain. The best known of these is naloxone.
The
opioid peptides induce analgesia in several ways. The first is by blocking pain
signals as they enter from the periphery into the dorsal horn region of the
spinal cord. The second is by blocking the transmission of pain impulses on
their way upward to the brain at supra-spinal levels. The third is by
stimulating higher neural mechanisms that send messages down to block pain at
lower and spinal cord levels.
Another
transmitter substance known as serotonin acts in the midbrain area of the brain
and is also involved in producing analgesia. Both central serotonin and the
endorphins regulate systems that can slow the pulse, lower blood pressure, and
inhibit over action of body organs. This is known as splanchnic activation and
occurs after acupuncture stimulation. It is of interest that this effect is
more pronounced in persons who have hypertension and other bodily
dysfunction's. This is in keeping with the widespread belief that acupuncture
produces a return to resting levels when the body homeostatic mechanisms are
disturbed.
Evidence
in support of the observation that acupuncture can decrease pain by release of
an endogenous substance with opiatelike activity ( endorphins, enkephalins, or
dynorphins ) is demonstrated by the fact that acupuncture analgesia in humans
can be reversed by giving naloxone.
It is
of interest that analgesia can also result from painful and stressful
manipulation of the body. This probably involves other pathways. Thus analgesia
may come about by descending impulses in both opiate and non-opiate analgesic
systems. Jogging and strong physical exercise are commonly recognised as
relieving chronic pain.
This
"jogger's high" probably occurs from stimulation of muscle afferents
and may involve nerve pathways that are stimulated by electro-acupuncture over
points where nerves enter muscles. Psychiatrists have long considered
depression to be one of the most painful of illnesses and jogging and exercise
are often part of programs designed to treat depression.
Pain
can be controlled in several ways. Surgical cutting of nerves can produce areas
of local analgesia. This is not a good way to control chronic pain, as pain
involves the whole nervous system, spinal cord, lower brain centres, and
cortex. Melzac and others have said that chronic pain is like a pain memory
involving reverberating, self sustaining neural circuits in the brain. This is
demonstrated by persons who have "phantom limb pain". This is a pain
that persists in an arm or leg after amputation of a limb or body part.
Commonly
patients attempt to control pain by taking "pain pills". This is no
cure but simply gives temporary relief.
Once
taken such pills must usually be continued over long periods of time. This
results in a continuing expense. There are many side effects that can occur
with such medications.
Acupuncture
and Pain
In the
last two decades international researchers in China and elsewhere have rendered
obsolete the metaphysical explanations of how acupuncture works to control
pain. When Western physicians visited China in the early 1970's they witnessed
surgery done with no chemical anaesthesia but only electro-acupuncture for
analgesia. Explanations in terms of metaphysical Yin and Yang, and meridian
theories made no sense to scientifically trained doctors and so they decided
that acupuncture was a kind of Oriental hypnosis.
The
National Institute of Health granted the first award to our laboratory at the
Missouri Institute of Psychiatry in 1971 for the study of acupuncture. We used
healthy volunteers exposed to experimental pain produced by both cold pressor (
water bath ) and electric shock. We compared the protective effect of hypnosis,
10 mg of morphine sulfate given intra-muscularly, and acupuncture. The latter
was administered with needles inserted both at specific ( acupuncture ) and non
specific ( placebo ) points, with and without electrical stimulation.
We
found that hypnosis, electro-acupuncture and morphine sulfate were all able to
reduce experimental pain at a level of statistical significance. While needle
insertion alone at acupuncture points were somewhat effective, the addition of
electricity to needles increased the analgesic response.
The
most significant reaction occurred with needles inserted at specific points and
stimulated electrically. Our poor and good hypnotic subjects responded equally
well to acupuncture and hence we concluded that hypnosis was not a significant
part of the acupuncture response.
We were
able to identify some points of measurable electrical potential on the arms of
our patients that differed from surrounding skin areas. Some of these points
were identical to classical acupuncture points. These also turned out to be
locations described as the motor points used to stimulate nerves by
electromyographers ( EMG points ). This observation agreed with reports by Liu
et al. ( 1975 ), Gunn (1977 ), and others, that the important and useful
acupuncture points are actually motor points, Golgi tendon organs, and points
adjacent to major nerves. It is also of interest that the painful "ah
shi" ( in Chinese "oh yes") points of acupuncture are the tender
trigger points described in the American literature by Travell.
We
found that acupuncture was not hypnosis and that electrical stimulation was
necessary to cause a significant reduction of the experimental pain.
Jisheng
Han and his co-workers in Beijing conducted systematic studies on the
neuro-chemical mechanisms of acupuncture. These began with observations of
surgical patients receiving acupuncture analgesia where it was noted that with
continued electrical stimulation the pain threshold continued to rise over a 30
minute period and returned gradually to the pre-stimulation level when the
electrical stimulation of the acupuncture needles was stopped. This prompted
experiments involving the cross-infusion of cerebrospinal fluid from an animal
that had developed electro-acupuncture analgesia and was injected into the
brain of a non-stimulated animal, this produced a similar, but smaller
analgesic reaction. This showed that the electro-acupuncture stimulation had
produced a chemical change in the cerebrospinal fluid taken from the stimulated
animal that was transferred into the non-stimulated animal producing a rise in
the pain threshold.
This
observation led to a series of experiments over ensuing years that showed that
a number of classical transmitters were released by the electro-acupuncture
stimulation.
Sjolund,
Terenius, and Erickson (1977), demonstrated that endorphins are increased in
cerebrospinal fluid with electro-acupuncture stimulation. Han tested samples of
spinal fluid from human volunteers. He was able to demonstrate increases in
various neuropeptides that occurred by simply changing the frequency of
electrical stimulation without moving the needle inserted into an acupuncture
point ( motor point ). These changes were frequency specific. Thus with
stimulation at a low frequency ( 2 Hz ) he found a rise in endorphins. 15 Hz
produced a rise in endorphins and enkephalins. High frequency ( 100 Hz )
produced a rise in dynorphin. The increase of the respective neuropeptides
occurred throughout the 30 minute period of stimulation. Thus, it appears
warranted to conclude that the release of various endogenous opioids like
peptides show that electro-acupuncture is frequency specific and not point
specific. Therefore, one can selectively increase the release of a certain type
of endorphin by selecting a specific frequency of stimulation to treat a
symptom or syndrome.
The
frequency of electrical stimulation is more important than the placement of
needles. A recent study by Han compared the use of electrically stimulated
acupuncture needles with conducting polymer pad electrodes.
He used
different frequencies of stimulation and found that with all frequencies
studied the pads were as effective in pain control as needles. Thus, it can be
concluded that for pain control it is essential to use electrical stimulation,
that the frequency of stimulation is important, that the points stimulated
should be motor points where nerve enters muscle and that needles are no longer
essential but rather the stimulation can be done with pad electrodes placed on
the skin.
Clinical
Use of Acupuncture for Pain Control
Acupuncture
treatments for pain are usually given in a surgery. The patient lies
comfortably on a couch. Needles should be very fine diameter, almost like a
small hair or bristle. So there is no danger of transferring infection from one
patient to another disposable needles are used. These needles are so flexible
their insertion is assisted by means of a small plastic tube which is held
against the skin with the handle of the needles protruding an inch above the
end of the tube. The end of the needle penetrates the skin without pain when
tapped lightly.
Conducting
polymer electrodes are just as efficient as needles, where these can be used,
and may be preferable to needles, in some cases treatments may be given using
both needles and pad electrodes.
Electro-pulsing
makes treatment more effective, therefore, all treatment is electrical. The
frequency of current used is important as specific frequencies release specific
neuropeptides. Often a so called, "dense - disperse" setting of the
stimulator is used. In this setting the current alternates between a very slow
frequency, about 2 cycles per second which releases endorphins and a high
frequency that releases enkephalins or dynorphins.
The optimal
time for a treatment is 30 minutes. Initially treatments are once or twice a
week although for acute conditions use up to daily treatments. The interval
between treatments lengthens as the patient improves. Often patients will
obtain sufficient pain relief with only 10 or 12 treatments. At times a
maintenance program is necessary with treatments being continued on a monthly
basis. Sometimes patients will obtain complete relief with a few treatments but
may find the pain later returns. Another session of a small number of
treatments may produce lasting relief.
Generally,
increasing the intensity and length of electro-acupuncture stimulation within a
range will increase the analgesic effect of acupuncture. The attempts to get
pain under control by unlimited length of stimulation is not a good idea.
The excessive release of endorphins by hours of stimulation
will activate the endogenous opioid system. Cholecystokinin, for example, is
one of the neuropeptides in the brain that antagonises the analgesia produced
by the endorphins. The prolonged electro acupuncture stimulation increases
cholecystokinin synthesis and release that is at least partially responsible
for the decrease in acupuncture effectiveness.
Case
Illustrations
The
setting is the waiting room in the office of Dr. George Ulett. Patients are
sitting around talking of their illnesses and the experience they have had with
electro-acupuncture treatments for their chronic pain problems. The patient's
anonymity is maintained by changing their names and histories.
Mr.
Abel is 55 years old and came with Chronic Lower Back Pain. "I am a
farmer and I guess I hurt my back riding the tractor over the rough fields. My
family doctor sent me to an orthopaedist who said I had a lumbar disc partly
protruding. He said it was pressing on a nerve and that's why I had pain. I
have had 10 acupuncture treatments and now my pain is 80% better. I know I will
have to take it easy for a while but then I can go back to work if I am
careful".
Miss
Barker is a 34 year old secretary who had Tennis Elbow. "I have
played tennis for years but last spring I began to have pain in my elbow and
down my forearm. There is one spot on my elbow that is sore to touch. I have
had 6 treatments with electro-acupuncture and now the pain is beginning to
leave".
Mrs.
Charles is a 37 year old housewife who complains of pain radiating from her hip
down to her ankle on the left side. Her diagnosis is Sciatica. She had
ten acupuncture treatments a week apart, and had almost complete relief but
after two weeks she again began to have some discomfort. Now she comes in every
two to three weeks for maintenance treatments and these keep her in comparative
comfort.
Mr.
Doga is a 65 year old retired salesman. He was lifting a suitcase into an
aeroplane overhead rack when the suitcase slipped. He tried to grab it and
wrenched his shoulder. He now has Chronic Shoulder Pain. His family
physician said he had a rotator cuff tear and injected him with cortisone. He
had some relief but the pain returned. An orthopaedic surgeon said he could
operate but could not guarantee success. He has had physical therapy but with
little relief Over-the-counter pain pills upset his stomach. He has been
getting acupuncture weekly now for three months. This treatment greatly relieved
the pain. He still gets some discomfort if he sleeps on the affected side but
otherwise if he is careful he no longer has pain.
Miss.
Eagle is a 43 year old widow. She comes in with pain that involves the whole of
her left face from forehead to chin. It is a jabbing type of pain that comes
and goes. She has seen many physicians and tried many medicines. She has been
told surgery would involve cutting her trigeminal nerve and would leave her
face numb. Her latest diagnosis was Atypical Facial Neuralgia. "I
have tried all kinds of medicine and been seen by about 5 doctors. None of them
could give me any relief. Last year I came here and had 9 electrical
acupuncture treatments and my pain entirely went away. I was free of pain for a
year and then it came back again. Then I had to have 5 treatments. The pain
entirely disappeared. Today I came back for a check-up after two years. I have
been completely pain free".
Mr.
Fitch, aged 47 is a disabled carpenter who enters with pain in his right leg.
His illness began with sciatica. After several hospitalisations with traction
and much physical therapy he began to have vascular changes in both legs.
Sympathetic injections were given but without success. At times the pain is so
severe that he cannot walk. The discolouration, pain, and vascular changes led
to a diagnosis of Sympathetic Reflex Dystrophy. "I have finally
gotten some relief. I am not well by any means but the electro-acupuncture
treatments so far have brought me relief that no other treatment has".
"I
am a 79 year old widow", said Mrs. Gramm. "I have been told by my
family doctor that the x-rays showed I have osteoarthritis. These
acupuncture treatments are really helping".
Joe
Heelma is a 49 year old avid fisherman. Almost every year in the fall he has a
series of incapacitating headaches. "These are cluster headaches",
he said. I have been to internists, neurologists, allergists, and even a
neurosurgeon. They are always on my left side and seem to be set off by a
tension that develops in my neck and shoulder. Since having an 8 week course of
acupuncture treatments followed by one treatment every month I have now gone
two years without the usual bout of headaches".
Other
patients joined the group discussing their ailments that had been helped by
acupuncture. These included, migraine headaches, tinnitus, fibromyalgia,
chronic knee pain and others.