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) and pain —muscle tension  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): affective quality, evaluative quality sensory 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” “peripherally acting” opioid drugs and nonopioid drugs

Opioid Analgesics

 Formerly called narcotics  Agonists (excitatory chemicals – e.g., morphine) act on receptors in the brain and spinal cord  Patient controlled analgesia control and undermedication — addresses

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 stimulus  Transcutaneous 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 interventions  used 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 triggers for responding to pain  Promote increased exercise and activity levels

Cognitive-Behavioral Interventions

 Biofeedback / muscle relaxation  Cognitive distraction  Imagery / virtual reality therapy Aug 2004) (see Sci American  Hypnosis  Cognitive restructuring — illogical beliefs and maladaptive thoughts (next slide) to challenge

Cognitive Errors in the Thinking of Pain Patients

 Catastrophizing and discomfort — overestimating distress  Overgeneralizing — global and will ruin one’s life and stable attributions that pain will never end  Victimization —  Self-blame Why me?

 Dwelling 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 pain  Overall, 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