chronic pain. what is pain? a sensory and emotional experience of discomfort. single most common...
TRANSCRIPT
Chronic Pain
What is pain? A sensory and emotional
experience of discomfort.
Single most common medical complaint.
Qualities of Pain Organic vs. psychogenic Acute vs. chronic Malignant or benign Continuous or episodic
Perceiving Pain 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 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 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
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 Mechanistic view
Could not account for the role of psychological factors.
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 thereby modulating pain.
Gate is located in the spinal cord.
Gate-Control Theory
Brain
Spinal Cord
GatingMechanism
TransmissionCells
Frompainfibers
FromotherPeripheralfibers
Tobrain
Brain
Spinal Cord
GatingMechanism
TransmissionCells
Frompainfibers
FromotherPeripheralfibers
Tobrain
Gate is open Gate is closed
Three Factors Involved in Opening and Closing the Gate 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
Physical conditions Extent of injury Inappropriate activity level
Emotional conditions Anxiety or worry Tension Depression
Mental Conditions Focusing on pain Boredom
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
Four Types of Pain Behaviours Facial/audible expression of
distress Distorted ambulation or posture Negative affect Avoidance of activity
Emotions, Coping, and Pain Chronic pain is associated with
higher levels of anger, fear, sadness, anxiety and stress.
Coping with Pain MMPI Scales 1 – 3
Hypochondriasis Depression Hysteria
Neurotic triad – combination of scales 1 – 3 of the MMPI
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 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 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 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: PRN – “as needed” As a prescribed schedule
Types of Pain Medications 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
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
Acupuncture – not sure how it works. Could include: 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