Psychology 2036A/B Lecture Notes - Lecture 5: Pain Management, Hypnosis, Lesley Collier

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Psychology of Health
Pain
Chapter 10
Prologue
Pain is a serious and prevalent health problem
E.g., the costs add up to $10 billion/year in Canada
It is by far the most common medical complaint
-symptoms that’s most likely to send people to seek treatment
for example, you may seek help if you have a lump but more likely to seek
help if it’s a painful lump;
-also the thing people fear most about treatment
Pain comes in many different forms (from “flickering” to “torturing” see page
302 *don’t memorize all this information)
Pain can be short term and acute, or continuous and chronic
Usually we want to get rid of pain, BUT some people actually enjoy the
sensation of pain;
It is a puzzling phenomenon
The Puzzling Phenomena of Pain
A. A world without pain an ideal place to live?
However, The case of Miss C, a student at McGill university;
Indicates that she was a highly intelligent student who appeared normal (hearing,
sight, touch, taste, etc);
BUT she was incapable of experiencing pain;
Known as “Congenital pain insensitivity”;
This causes many problems: e.g., as a young child she bit off the tip of her tongue
and was not aware of it, at another occasion she got 3rd degree burns on her knees
while kneeling on a hot radiator while looking out the window
-In lab they gave her electrical shock and she did not feel pain, or to extremely hot or
cold water; she did not feel any physiologically changes while exposed (her HR, BP,
and respiration stayed the same)
-she never took the precautions to protect her joints, for e.g., she never turned over
during sleeping, she never shifted her weight while sitting or standing, interestingly
she could not remember ever sneezing or coughing
-she did not have an eye blink reflex
Unfortunately, Miss C died at the age of 29 because of infections that occurred
because she was insensitive to pain.
-Some people who cannot experience pain died because they did not realized
appendix had ruptured, or that they were having a heart attack
-Like Miss C, Sarah (video), is insensitive to pain
-THE EXPERIENCEO OF PAIN IS ESSENTIAL FOR SURVIVAL
More common than pain insensitivity is…
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B. Pain with no apparent physical cause.
-In some cases the pain is from physical causes, but it is mysterious because it
persist a long time after injury is healed
1. Neuralgia (pain along length of a nerve)
E.g., Trigeminal neuralgia (pain in face);
A pain occurs around trigeminal nerve which is in the face;
-Pain provoked by innocuous stimuli (cottonball)
2. Causalgia (caused by episode of severe burning pain)
-pains persists long after original wound is healed
-provoked by innocuous stimuli (puff of air)
3. Phantom limb pain (pain in amputated limb)
-limb is no longer there, but they continue to experience pain in the region where
the limb was
e.g., person who lost his limb from the elbow reported his wrist felt like it was bent
back and was extremely painful; there was no way to relief the pain because the
limb is not actually there
C. Pain is influenced by psychological factors
1. Beecher’s observations (p. 298)
-Beecher was a surgeon during WW2
-Observed severely wounded soldiers –only 25% requested morphine to ease their
pain;
-a few years after the war, Beecher studied civilian men who had just undergone
surgery (surgery wounds were less extensive), but 80% requested morphine
He asked: why did the soldiers who had worse wounds perceived the pain as less?
-he noted it was the differences in the “meaning” of pain
-for the soldiers, “war is over and I’m finally going home; to them pain was a good
thing”
-for the civilians, “beginning of a long recovery process that will disrupt my life”
2. Other psychological factors;
-Perceived control over pain;
E.g., when people think they are in control over their pain they experience less pain
-Focus of attention; when people are distracted the pain is perceived as less severe
or gone
-Guided Imagery (319-320); this is a distraction
Summary: Pain is puzzling because there is often no direct relation between
physical injury and the experience of pain. Why?
Not a complete answer, but 1 theory designed to answer this question…
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The Gate-Control Theory of Pain (p. 303)
Part 1: The Physiology of Pain Reception
A. Body experiences tissue damage
1. Algogenic substances released at the site of damage;
these chemicals activate the immune system, and this causes inflammation.
2. Free nerve ending are stimulated in the damaged area (called “nociceptors” – pain
fibres)
B. Two types of nociceptors
1. A-delta fibers (myelinated (insulated) and fast; they transmit pain sensations very
quickly), these fibers are associated with sharp, localized, distinct pain sensation
2. C-Fibers (unmyelinated and slow; associated with dull, diffuse, burning, or aching
pain sensation)
3. Also: A-beta fibers (myelinated and fast);
-transit innocuous/harmless sensation (e.g., gentle rubbing, light scratches)
-they do not transmit pain sensations, these A-beta fibers do however play an
important role
4. There fibers send messages to the spinal column (dorsal horn)
C. Activity in dorsal horn (substanstia gelatinosa)
1. Pain fibers released “substance P”
2. Substance P activates Transmission cells (send “pain “messages to the brain)
3. Transmission cells can be inhibited, which inhibits the sensation of pain
-DEPENDS on whether the gate is OPEN or CLOSED
Part 2: The Gating Mechanism
A. Located in substantia gelatinosa of the dorsal horn
If OPEN, substance P activates transmission cells (send pain messages to
brain);
If CLOSED, transmission cells are inhibited
B. What controls the gate?
1. Activity in pain fibers (A-delta and C);
-opens the gate
-the more activity in A-delta and C fibers, the stronger the signal
2. Activity in A-beta fibers;
-closes the gate
3. Messages that descend from the brain controls the opening and closing of
gate
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