Chapter 7 - Understanding & Managing Pain

Physiology of Pain

What parts of the body are involved in experiencing pain? (BSS)

1. Brain

2. Spinal Cord

3. Somatosensory System

Somatosensory System

• What it does?

• Contains…

• Conveys sensory info from the body to brain

• Contains

  • Afferent neurons

  • Efferent neurons

  • Interneurons

Afferent Neurons

Sensory neurons — relay info from sense organs → brain

Efferent neurons

Motor neurons — result in the movement of muscles / stimulation of organs or glands

Interneurons

Connect sensory to motor neurons

Nociception

• What is it?

• What are nociceptors?

• Nociception—process of perceiving pain

• Nociceptors—receptors in skin + organs; responds to stimulation that may cause tissue damage

Spinal Cord

• Avenue for sensory info—travels toward brain & motor info comes from it

• Provides spinal reflexes—react w/o processing it

Process

Somatosensory Cortex

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• Motor cortex

• Sensory cortex

The Experience of Pain

Pain is a s— experience & e— experience

• Sensory experience—-somatosensory cortex tells you where it is + how strong it is

• Emotional experience—insula cortex & anterior cingulate cortex tell you how much it bothers, annoys, or disturbs you

Main Theories of Pain

1. Specificity Theory

2. Gate Control Theory

3. Neuromatrix Theory

Specificity Theory

• What?

• Pain is the result of — — — —

• Experience of pain is approximately = to amount of tissue damage/bodily injury

• Pain is the result of transmission of specific signals

Henry Beecher

• Who?

  • Found what?

• Anesthesiologist for soldiers in WWII

  • Found that despite serious battle injuries, many of men reported very little pain

Henry Beecher found that

Phantom Limb Pain

• What is it?

• Reported by…

• Why does it occur?

• What: Sensation of pain from a limb that has been lost; person no longer receives physical signals

• Who: Reported from amputees / quadriplegics

• Why? Even when limb is amputated → brain represents limb in somatosensory cortex

Bottom-up processes vs. Top-down processes

Bottom-up—afferent neurons send messages to spinal cord + brain

Top-down—brain & spinal cord decides how messages from the afferent neurons affect the brain

Gate Control Theory

• Psychological influences are manifested in the brain may influence the experience of pain

• During a war or sports victory, the brain sends messages closing the gate

Gate Control Theory

• What controls the gate?

• The amount of activity in the pain fibers

• Messages from the brain

Gate control theory

• What opens the gate?

  • Physical

  • Cognitive

  • Emotional

• Physical

  • Extent of injury

  • Inappropriate activity level

• Cognitive

  • Focus on the pain

  • Boredom

• Emotional

  • Anxiety, worry

  • Depression; anger

Gate control theory

• What closes the gate?

  • Physical

  • Cognitive

  • Emotional

• Physical

  • Meds

  • Heat, massage

  • Pressure

• Cognitive

  • Distraction

  • Concentration

• Emotional

  • Relaxation

  • Positive emotions

Affect influences chronic pain by…

• Ex: arthiritis

• People with arthirits who’s more depressed &/or anxious → more pain

Neuromatrix Theory

• An extension of — theory

• What?

• Melzack’s extension of gate control theory

• How different parts of the brain are involved in the increasing / decreasing experience of pain

What can affect experience of pain?

1. Unpleasantness

• Multiple people with the same pain stimulus → all would rate it differently in terms of unpleasantness

What can affect experience of pain?

2. Context of Pain

• Same person had same stimulus (pos/neg) at different times → pain experience ↗ when you find out something about negative stimulus vs positive stimulus

What can affect experience of pain?

3. Influences on Pain

Classifying Pain

Acute Pain

Adaptive; lasts short

• Ex: pain from cuts, burns, & other physical trauma

• Typically soft tissue damage, infection, and/or inflammation among other causes

• slide 28

Chronic Pain

Longer than normal healing; constant

• Often reinforced by other people + becomes self-perpetuating

• Typically w/ capable older adults

• slide 29

• Can trigger psychological problems

• Defined as “disease of pain”

Features of Chronic Pain

1. Persists long after healing

2. May spread + increase in intensity

3. May become stronger than initial pain from injury

Chronic Pain Conditions

1. Arthritis

2. Migraine headaches

3. Lower back pain

4. Fibromyalgia

1. Arthritis

Pain caused by inflammation in the joints

2. Migraine

Recurrent, throbbing, very painful headaches

3. Lower back pain

Chronic low back

Pre-chronic Pain

Experienced B/T acute & chronic pain; critical

• Pain can either go away or turn into chronic pain

Lower Back Pain

• What contributes to it?

• Lead to…

• Only —% have identified cause

• What:

  • Infections

  • Degenerative disease

  • Cancer (rare)

  • Injury / physical stress

• Lead to

  • Musculoskeletal

  • Ligament

  • Neurological problems

• Only 20% have identified cause

Fibromyalgia

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Cancer Pain

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Measurement of Pain

Types of Measures

1. Self-report

2. Behavioral assessment

3. Physiological measures

1. Self-report

• Visual Analogue Scale

• Pain intensity—from somatosensory

• Pain unpleasantness—from insula; anterior cingulate cortex

• Visual Analogue Scale—place mark on line to indicate how much pain you are feeling

  • Distance from left is measured for pain score

2. Behavioral assessment

• What do you do?

  • What to look for?

• Good for..

• Watch to see if they exhibit pain behaviors

  • Guarded movement

  • Bracing

  • Position shifts

  • Partial movement

  • Grimacing

  • Limitation statements

  • Emitting pain sounds

• Good for kids + older adults

3. Physiological measurement

• Tried to do muscle tension + autonomic NS response

• But, don’t show sufficient reliability / validity

Medical Professionals typically…

• Underestimate pain of patients

• May prescribe / administer too little pain meds

Why may doctors prescribe / administer too little pain meds?

• Fear of addiction to opiate drugs

Treatment of Pain

— drugs are the most common treatment for acute pain

• Drugs fall into 2 groups:

Analgesic drugs are most common treatment for acute pain

• 2 groups:

  • Opiates

  • Nonnarcotic analgesics

Opiates

• Powerful analgesic effects, but also produce tolerance & dependence

• Fear of addiction typically under-prescribed → may harm pain recovery

Why has there been an increase in prescription of analgesic drugs?

Would oxycontin lead to less / more active coping w/ pain?

• Demand of oxycodone (oxycontin) & hydrocodone

• More active coping

NSAIDS

• Useful for..

• Examples:

• Useful for managing minor pain, especially pain due to injury

• Ex:

  • Ibuprofen (Advil)

  • Naproxen (Aleve)

  • Aspirin

Too much ibuprofen causes..

• Organ damage

  • ibuprofen → kidneys

  • Tylenol → liver

Surgical Intervention

slide 48

Treatment of Pain

slide 49

Behavioral & Cognitive Interventions

Slide 50

Progressive Muscle Relaxation

Why do some people still experience pain

slide 52 reinforcement of pain

Behavior Modification

slide 53

Progression

slide 54