Transcript Chronic Pain

Chronic Pain
What is pain?
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A sensory and emotional experience of
discomfort.
Single most common medical complaint.
Qualities of Pain
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Organic vs. psychogenic
Acute vs. chronic
Malignant or benign
Continuous or episodic
Perceiving Pain
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Algogenic substances – chemicals
released at the site of the injury
Nociceptors – afferent neurons that
carry pain messages
Referred pain – pain that is perceived
as if it were coming from somewhere
else in the body
Peripheral Nerve Fibers
Involved in Pain Perception
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A-delta fibers – small, myelinated fibers
that transmit sharp pain
C-fibers – small unmyelinated nerve
fibers that transmit dull or aching pain.
A-delta fibers
Pain without apparent physical
basis
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Persists long after healing
May spread and increase in intensity
May become stronger than was the
initial pain from the injury
Three Chronic Pain Conditions
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Neuralgia – an extremely painful condition
consisting of recurrent episodes of intense
shooting or stabbing pain along the course of the
nerve.
Causalgia – recurrent episodes of severe burning
pain.
Phantom limb pain – feelings of pain in a limb
that is no longer there and has no functioning
nerves.
Early Theories of Pain
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Mechanistic view
Could not account for the role of
psychological factors.
Gate-Control Theory –
Ronald Melzack (1960s)
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Described physiological mechanism by
which psychological factors can affect
the experience of pain.
Neural gate can open and close thereby
modulating pain.
Gate is located in the spinal cord.
Gate-Control Theory
Gate is closed
Gate is open
Brain
Brain
To
brain
From
pain
fibers
Gating
Mechanism
From
other
Peripheral
fibers
Transmission
Cells
Spinal Cord
To
brain
From
pain
fibers
Gating
Mechanism
From
other
Peripheral
fibers
Transmission
Cells
Spinal Cord
Three Factors Involved in
Opening and Closing the Gate
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The amount of activity in the pain
fibers.
The amount of activity in other
peripheral fibers
Messages that descend from the brain.
Conditions that Open the Gate
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Physical conditions
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Emotional conditions
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Extent of injury
Inappropriate activity level
Anxiety or worry
Tension
Depression
Mental Conditions
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Focusing on pain
Boredom
Conditions That Close the
Gate
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Physical conditions
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Emotional conditions
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Medications
Counter stimulation (e.g., heat, message)
Positive emotions
Relaxation, Rest
Mental conditions
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Intense concentration or distraction
Involvement and interest in life activities
Four Types of Pain Behaviours
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Facial/audible expression of distress
Distorted ambulation or posture
Negative affect
Avoidance of activity
Emotions, Coping, and Pain
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Chronic pain is associated with higher
levels of anger, fear, sadness, anxiety
and stress.
Coping with Pain
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MMPI Scales 1 – 3
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Hypochondriasis
Depression
Hysteria
Neurotic triad – combination of scales 1 –
3 of the MMPI
Three conclusions from the
MMPI studies of pain
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Chronic pain is associated with very high scores on
the three scales of the neurotic triad, although
scores on the other scales are within the normal
range.
This pattern holds regardless of whether there is a
known cause for the pain.
Individuals with acute pain may show moderate
elevations of the neurotic triad scales, although
scores on the other scales are normal.
Treatment of Chronic Pain
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Surgical procedures to block the
transmission of pain from the peripheral
nervous system to the brain.
Synovectomy – Removing membranes
that become inflamed in arthritic joints.
Spinal fusion – joins two or more
adjacent vertebrae to treat chronic back
pain.
Pharmacologic Control of Pain
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About half of hospitalized patients who
have pain are under-medicated.
Children are at particular risk of poor
pain control methods.
Medications are given as:
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PRN – “as needed”
As a prescribed schedule
Types of Pain Medications
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Peripherally active analgesics – work at the
periphery (e.g., aspirin, Tylenol).
Centrally active analgesics – narcotics that bind to
the opiate receptors in the brain (e.g., codeine,
morphine, heroin).
Local analgesics – can be injected into the site of
injury or applied topically (e.g., novocaine).
Indirectly acting drugs – affect non-pain
conditions such as emotions that can exacerbate
pain experience.
Psychological Pain Control
Methods
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Biofeedback – provides biophysiological
feedback to patient about some bodily
process the patient is unaware of (e.g.,
forehead muscle tension).
Relaxation – systematic relaxation of the
large muscle groups.
Hypnosis – relaxation + suggestion +
distraction + altering the meaning of pain.
Psychological Pain Methods
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Acupuncture – not sure how it works.
Could include:
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Counter-irritation – may close the spinal
gating mechanism in pain perception.
Expectancy
Reduced anxiety from belief that it will work.
Distraction
Trigger release of endorphins