lecture 7 chronic pain

8/13/2019 Lecture 7 Chronic Pain

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Chronic Pain


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What is pain?A sensory and emotional experience of

discomfort.

Single most common medical complaint.


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Qualities of Pain Organic vs. psychogenic

Acute vs. chronic

Malignant or benign

Continuous or episodic


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Perceiving PainAlgogenic substanceschemicals

released at the site of the injury

Nociceptorsafferent neurons thatcarry pain messages

Referred painpain that is perceived

as if it were coming from somewhereelse in the body


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Peripheral Nerve Fibers

Involved in Pain PerceptionA-delta fiberssmall, myelinated fibers

that transmit sharp pain

C-fiberssmall unmyelinated nervefibers that transmit dull or aching pain.

A-delta fibers


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Pain without apparent physical

basis Persists long after healing

May spread and increase in intensity

May become stronger than was theinitial pain from the injury


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Early Theories of Pain Mechanistic view

Could not account for the role ofpsychological factors.


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Gate-Control Theory

Ronald Melzack (1960s) Described physiological mechanism by

which psychological factors can affect

the experience of pain.

Neural gate can open and close therebymodulating pain.

Gate is located in the spinal cord.


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Gate-Control Theory

Brain

Spinal Cord

GatingMechanism

TransmissionCells

Frompainfibers

Fromother

Peripheralfibers

Tobrain

Brain

Spinal Cord

Gating

Mechanism

Transmission

Cells

Frompainfibers

FromotherPeripheral

fibers

Tobrain

Gate is openGate is closed


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Three Factors Involved in

Opening and Closing the Gate The amount of activity in the pain

fibers.

The amount of activity in otherperipheral fibers

Messages that descend from the brain.


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Conditions that Open the Gate Physical conditions

Extent of injury

Inappropriate activity level Emotional conditions

Anxiety or worry

Tension

Depression Mental Conditions

Focusing on pain

Boredom


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Conditions That Close the

Gate Physical conditions

Medications

Counter stimulation (e.g., heat, message) Emotional conditions

Positive emotions

Relaxation, Rest

Mental conditions

Intense concentration or distraction

Involvement and interest in life activities


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Four Types of Pain Behaviours Facial/audible expression of distress

Distorted ambulation or posture

Negative affect

Avoidance of activity


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Emotions, Coping, and Pain Chronic pain is associated with higher

levels of anger, fear, sadness, anxiety

and stress.


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Coping with Pain MMPI Scales 13

Hypochondriasis

Depression

Hysteria

Neurotic triadcombination of scales 1

3 of the MMPI


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Three conclusions from the

MMPI studies of pain 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 normalrange.

This pattern holds regardless of whether there is aknown cause for the pain.

Individuals with acute pain may show moderateelevations of the neurotic triad scales, althoughscores on the other scales are normal.


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Treatment of Chronic Pain Surgical procedures to block the

transmission of pain from the peripheral

nervous system to the brain. SynovectomyRemoving membranes

that become inflamed in arthritic joints.

Spinal fusion

joins two or moreadjacent vertebrae to treat chronic backpain.


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Pharmacologic Control of PainAbout half of hospitalized patients who

have pain are under-medicated.

Children are at particular risk of poorpain control methods.

Medications are given as:

PRNas needed

As a prescribed schedule


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Types of Pain Medications Peripherally active analgesicswork at the

periphery (e.g., aspirin, Tylenol).

Centrally active analgesics

narcotics that bind tothe opiate receptors in the brain (e.g., codeine,morphine, heroin).

Local analgesicscan be injected into the site of

injury or applied topically (e.g., novocaine). Indirectly acting drugsaffect non-pain

conditions such as emotions that can exacerbatepain experience.


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Psychological Pain Control

Methods Biofeedbackprovides biophysiological

feedback to patient about some bodily

process the patient is unaware of (e.g.,forehead muscle tension).

Relaxationsystematic relaxation of the

large muscle groups. Hypnosisrelaxation + suggestion +

distraction + altering the meaning of pain.


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Psychological Pain MethodsAcupuncturenot sure how it works.

Could include:

Counter-irritationmay close the spinalgating mechanism in pain perception.

Expectancy

Reduced anxiety from belief that it will work. Distraction

Trigger release of endorphins

lecture 7 chronic pain

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