Pain and its management

Significance of Pain

Pain A clear example of the mind–body

(BPS) model (and most common problem associated with going to HCP)

Adaptive as a biological warning signal (e.g., congenital insensitivity to pain)

The Physiology of Pain

“How you know that you stubbed your toe” handout 1. Nociceptor — a specialized neuron that

perceives and responds to painful stimuli 2. Special pain nerve fibers

A-Delta Fibers -- Large, myelinated (fast) nerve fibers that transmit sharp, stinging pain

C-Fibers -- Small, unmyelinated nerve fibers that carry dull, aching pain

The Physiology of Pain

“How you know that you stubbed your toe” handout 3. Dorsal Horn — pain’s “arrival” to the

CNS 4. Brain – perception of pain. Heavily

influenced by emotion, context, expectations, etc. (illustration next slide)

Pain Pathways

PAG area of midbrain (next slide)

Pain Pathways

Periaqueductal Gray (PAG)

midbrain region-- activates a descending neural pathway that uses serotonin to close the “pain gate”

Gate Control Theory

Proposed by Melzack & Wall (1965) A neural “gate” in the spinal cord

regulates the experience of pain Pain is not the result of a straight-

through sensory channel

The Gate Control Theory of Pain

The Biochemistry of Pain

Substance P (pain NT) NTs (e.g., serotonin) that alter “gate” Enkephalins, endorphins, dynorphins

(endogenous opioids)

Psychosocial Factors in the Experience of Pain

Stress pain perception is influenced by stress

(emotionality and pain experience) stress leads people to engage in behaviors

(i.e., grinding teeth, tensing muscles), which in turn lead to pain

Good news: Stress-Induced Analgesia (SIA) — a stress-related increase in tolerance to pain, mediated by the body’s endogenous opioids

Psychosocial Factors in the Experience of Pain

Learning modeling secondary gain / reinforcement culturally learned -- groups establish

norms for the degree to which suffering should be openly expressed and the form that pain behaviors should take

Psychosocial Factors in the Experience of Pain

Cognition anticipation of pain is often worse than

pain itself placebo and pain (e.g., child who gets ear

examined feels better)

expectations of ability to cope (e.g., control and pain – PCA morphine)

Pain Management

Overview: The Fifth Vital sign

Body Temp, Pulse, BP, Resp Rate, Pain

Measuring pain Chronic pain issues Treatment

Measuring Pain

Psychophysiological Measures Electromyography (EMG) —muscle

tension and pain Indicators of autonomic arousal — HR,

etc.

Measuring Pain

Behavioral Measures Pain Behavior Scale

e.g., vocal complaints, grimaces, awkward postures, mobility

Measuring Pain

Self-Report Measures Structured interviews (When did the

pain start? How has it progressed?) Pain rating scales (numerical ratings or

a pain diary) Standardized pain inventories

McGill Pain Questionnaire (MPQ): sensory quality, affective quality, evaluative quality of pain

Chronic Pain Management

Acute vs. Chronic pain Who becomes a chronic pain patient?

Not necessarily related to pain intensity More important are reactions:

Physical (postural changes)Functional disability (pain interferes with life activities)Reactions to pain episodes and to stress

The toll of chronic pain (video clips from “Psychology of Pain”)

The toll of chronic pain

Dysfunction report high levels of pain, feel they have little

control over their lives, and are extremely inactive Interpersonal distress

perceive little social support and feel other people in their lives don’t take their pain seriously

often poor communication sexual relationships deteriorate

Cost Huge medical bills Undergone many treatments (e.g., multiple

surgeries) and rely on painkillers Job loss/disability

Treating Pain

Pharmacological Treatments Analgesic (pain-relieving) drugs are the

mainstay of pain control Include “central acting” opioid drugs

and “peripherally acting” nonopioid drugs

Opioid Analgesics

Formerly called narcoticsAgonists (excitatory chemicals – e.g.,

morphine) act on receptors in the brain and spinal cord

Patient controlled analgesia — addresses control and undermedication

Nonopioid Analgesics

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) Aspirin, ibuprofen -- relieve pain and

reduce inflammation at the site of injured tissue

Other Medical Interventions

Counterirritation Analgesia in which one pain is relieved by

creating another, counteracting stimulusTranscutaneous Electrical Nerve

Stimulation (TENS) A counterirritation form of analgesia

involving electrically stimulating spinal nerves near a painful area

Cognitive-Behavioral Therapy

Cognitive-Behavioral Therapy (CBT) A multidisciplinary pain-management

program that combines cognitive, physical, and emotional interventionsused by 73% of clinicians who treat chronic

pain

Cognitive-Behavioral Therapy

Components Education and goal-setting component

is used to clarify client’s expectations Cognitive interventions to enhance

patients’ self-efficacy and sense of control over pain

Teaching new skills for responding to pain triggers

Promote increased exercise and activity levels

Cognitive-Behavioral Interventions

Biofeedback / muscle relaxationCognitive distraction

Imagery / virtual reality therapy (see Sci American Aug 2004)

HypnosisCognitive restructuring — to

challenge illogical beliefs and maladaptive thoughts (next slide)

Cognitive Errors in the Thinking of Pain Patients

Catastrophizing — overestimating distress and discomfort

Overgeneralizing — global and stable attributions that pain will never end and will ruin one’s life

Victimization — Why me?Self-blameDwelling on the pain

Reshaping Pain Behavior

Identify the events (stimuli) that precede pain behaviors (responses) as well as the consequences that follow (reinforcers)

Which Approach to Pain Control Works Best?

It depends on which type and aspect of painOverall, the most effective programs are

multidisciplinary in nature, combining the cognitive, physical, and emotional interventions of CBT with the judicious use of analgesic drugs

Effective programs also encourage patients to develop (and rehearse) a specific pain-management program

Group settings are probably most effective