Pain and its management

1. Pain and its management

2. 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)

3. 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

4. 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)

5. Pain Pathways  PAG area of midbrain (next slide)

6. Pain Pathways • Periaqueductal Gray (PAG) • midbrain region-- activates a descending neural pathway that uses serotonin to close the “pain gate”

7. 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

8. The Gate Control Theory of Pain

9. The Biochemistry of Pain • Substance P (pain NT) • NTs (e.g., serotonin) that alter “gate” • Enkephalins, endorphins, dynorphins (endogenous opioids)

10. 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

11. 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

12. 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)

13. Pain Management • Overview: • The Fifth Vital sign • Body Temp, Pulse, BP, Resp Rate, Pain • Measuring pain • Chronic pain issues • Treatment

14. Measuring Pain • Psychophysiological Measures • Electromyography (EMG) —muscle tension and pain • Indicators of autonomic arousal — HR, etc.

15. Measuring Pain • Behavioral Measures • Pain Behavior Scale • e.g., vocal complaints, grimaces, awkward postures, mobility

16. 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

17. 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”)

18. 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

19. Treating Pain • Pharmacological Treatments • Analgesic (pain-relieving) drugs are the mainstay of pain control • Include “central acting” opioid drugs and “peripherally acting” nonopioid drugs

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

21. Nonopioid Analgesics • Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) • Aspirin, ibuprofen -- relieve pain and reduce inflammation at the site of injured tissue

22. 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

23. 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

24. 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

25. Cognitive-Behavioral Interventions • Biofeedback / muscle relaxation • Cognitive distraction • Imagery / virtual reality therapy (see Sci American Aug 2004) • Hypnosis • Cognitive restructuring — to challenge illogical beliefs and maladaptive thoughts (next slide)

26. 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-blame • Dwelling on the pain

27. Reshaping Pain Behavior • Identify the events (stimuli) that precede pain behaviors (responses) as well as the consequences that follow (reinforcers)

28. 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