Chapter 11 Summary - Nature and Symptoms of Pain PDF

CHAPTER 11 THE NATURE AND SYMPTOMS OF PAIN CHAPTER OUTLINE I. What is Pain? A. Section introduction 1. Definition: pain is the sensory and emotional experience of discomfort usually associated with actual or threatened tissue damage 2. The...

CHAPTER 11 THE NATURE AND SYMPTOMS OF PAIN CHAPTER OUTLINE I. What is Pain? A. Section introduction 1. Definition: pain is the sensory and emotional experience of discomfort usually associated with actual or threatened tissue damage 2. The importance of pain a. virtually all people experience pain and it’s the most frequent medical complaint b. severe, prolonged pain may dominate the lives of its victims c. pain has economic and social consequences B. The qualities and dimensions of pain 1. Section introduction a. sensations of pain vary and have different qualities i. example - pain has been described as burning, throbbing, sharp, dull, itching b. pain also differs in origin and duration 2. Organic versus psychogenic pain a. organic pain results from tissue damage b. psychogenic pain occurs in the absence of organic damage c. researchers used to consider these separate entities but now concede that, simply because there are differences in presence of tissue damage, the psychological experience of pain is similar i. all pain involves interplay of physiological and psychological factors ii. organic and psychogenic pain now conceptualized as a continuum rather than dichotomy - different pain experiences involve a mixture of organic and psychogenic factors - example: pain disorder, a somatoform disorder, involves chronic pain with no detectable physical basis. iii. caution - not finding a demonstrated physical basis for pain doesn't mean there is none 3. Acute versus chronic pain a. length of pain experience is important descriptive dimension. i. most painful conditions are temporary and can be alleviated with medications or other treatments - generally similar painful conditions that occur in the future aren’t directly connected with an earlier pain experience ii. acute pain is temporary, usually less than six months - high anxiety while pain exists but subsides as pain decreases ii. chronic pain lasts more than a few months - high levels of anxiety that develops into feelings  of hopelessness and helplessness - pain interferes with activities, goals, sleep, loss of jobs with resulting low income b. factors used in description of chronic pain i. effects of chronic pain depend on whether underlying condition is: - benign or malignant - continuous or episodic c. types of chronic pain i. chronic/recurrent pain - benign causes characterized by repeated and intense episodes of pain - examples - migraine headaches, tension-type headaches, and myofascial pain ii. chronic/intractable/benign pain - discomfort present all the time with varying levels of intensity and not due to malignant condition - example - chronic low back pain iii. chronic/progressive pain - continuous discomfort associated with malignant condition and which becomes increasingly intense - examples - rheumatoid arthritis and cancer C. Perceiving Pain 1. Section introduction a. pain sense properties i. there are no specific receptor cells that transmit only pain signals ii. pain results from many types of noxious stimuli iii. pain includes a strong emotional component 2. The physiology of pain perception a. Noxious stimulation triggers chemical activity at site of injury i. serotonin, histamine, and bradykinin are released which promote immune system activity, cause inflammation, and activate nerve fibers ii. nociceptors - free nerve endings that carry information to spinal cord and brain - A-delta fibers are coated in myelin and are associated with sharp, well-localized, distinct pain - terminate in motor/sensory areas of brain - signal receives immediate attention  - C fibers are not coated with myelin and are associated burning, aching pain - terminate in the brainstem, forebrain and other diffuse regions of the brain - signal less likely to capture attention but more likely to affect mood, emotional state, motivation b. referred pain - pain originating in internal organs is often perceived as coming from other parts of the body i. results from shared spinal cord pathway for organ and skin - people more familiar with sensations from skin; mislabel pain signal as being from skin 3. Pain without detectable body damage a. onset of pain syndromes i. pain often began with tissue damage but persisted long after healing completed ii. pain spread and increased in intensity. iii. pain became stronger than pain from initial damage. b. types of pain syndromes i. neuralgia.- stabbing pain along the course of a nerve - example: trigeminal neuralgia – spasms of pain in face ii. causalgia - recurrent episodes of severe burning pain iii. phantom limb pain - sensation/pain in an amputated limb or limb with peripheral nerve damage c. suspected causes for pain syndromes i. some form of neural damage is suspect but doesn’t explain why people with obvious neural damage don’t also develop pain syndromes ii. full explanation is puzzle but probably some combination of physiological and psychological factors involved 4. The role of the "meaning" of pain a. masochists, individuals who like pain, attach a different meaning to pain, which is developed via classical conditioning b. Beecher's studies i. 49% injured soldiers during WW II rated pain was moderate or severe and 32% required medication. - pain signaled the end of their ordeal in battle. ii. 75% of surgical patients rated pain as moderate to severe and 83% requested medication. - pain signaled the beginning of a personal disaster. II. Theories of Pain A. Early theories of pain 1. Specificity theory - proposed that a separate system of receptors, peripheral nerves, pathway to brain, and area in brain for pain perception exists 2. Pattern theory - argued that pain receptors are shared with other senses and that the intense pattern of neural activity is perceived as pain 3. Criticisms of these theories a. pattern theory doesn't explain why innocuous stimuli produce causalgia and neuralgia b. theories don't explain why psychological factors contribute to pain experience i. example: people under hypnosis feel less pain B. The gate-control theory of pain 1. Section introduction a. theory developed by Melzack and Wall that integrates and improves on earlier theories i. suggests a physiological mechanism by which psychological factors affect pain ii. accounts for observations that earlier theories couldn't 2. The gating mechanism a. gating mechanism, which permits or inhibits pain signals, is located in the substantia gelatinosa of the dorsal horns of the spinal cord's gray matter i. A-delta and C fibers pass through the gate and stimulate transmission cells which send the signals to the brain. ii. the opening and closing of the gate is controlled by - the amount of activity in the pain fibers - the amount of activity in other peripheral fibers - messages from the brain iii. when the gate is open, pain is perceived 3. Evidence on the gate-control theory a. Empirical evidence i. supporting evidence - stimulation of the periaqueductal gray region of midbrain may produce analgesia in animals during painful stimulation and surgery - morphine works by activating brainstem to send impulses down spinal cord III. Biopsychosocial Aspects of Pain A. Neurochemical transmission and inhibition of pain 1. Effects of stimulation-produced analgesia (SPA) a. stimulation to the brainstem produces insensitivity to pain  b. substance P is produced by small-diameter pain fibers and crosses the synapse to the transmission cells, triggering activation of pain signals c. SPA occurs when substance P release is blocked 2. Stimulation of the periaqueductal gray area a. chain of activity i. stimulation to periaqueductual gray travels from brain to spinal cord ii. serotonin activates inhibitory interneurons which release endorphins which inhibit the release of substance P b. endogenous opioids (endorphin and enkephalin) and opiates (morphine and heroin) alleviate pain in same way – by binding to receptors in CNS, thus inhibiting substance P i. evidence: chronic pain patients have diminished levels of endogenous opioids in their blood 3. Mechanism of action for opiates and opioids a. naloxone blocks the action of opiates and opioids and the analgesic effect of electrical stimulation to periaqueductal gray area i. injections of naloxone are related to increased pain experiences b. role of endogenous opioids in pain and analgesia is complicated i. issues - nalaxone doesn’t always block SPA - neurotransmitters may have different effect on momentary vs. long term pain - chronic pain sufferers do not experience tolerance to morphine like is seen when morphine is taken for momentary pain c. having endogenous opioids serves adaptive function i. enables action to be taken to promote survival after serious injury or significant stress (e.g., battlefield stress) B. Personal and social experiences and pain 1. Learning and pain a. pain is learned through the association of pain with antecedent cues and consequences i. examples - distress associated with migraine aura; physiological reactions to words/phrases associated with pain ii. learning influences pain behaviors such as - facial/audible expression of distress - distorted ambulation or posture - negative affect - avoidance of activity  b. pain behaviors may be maintained by operant conditioning i. secondary gains through attention, being relieved of chores, receiving disability payments 4. Social processes and pain a. families give social reinforcement for pain through attention, (solicitous) care, and affection, which leads to a vicious cycle of even more pain behaviors i. being overly solicitous increases patients' dependency and decrease their self-efficacy and self-esteem 5. Gender, sociocultural factors, and pain a. women and men differ in types of pain and reactions to pain i. women - arthritis, migraine headache, myofacial neuralgia and causalgia; report pain interferes with daily activities ii. men - back pain and cardiac pain b. differences in pain reports among different sociocultural groups both between different racial-ethnic groups in the US and between US and other countries i. other studies have found no difference c. knowing about ethnic/gender differences doesn’t assist in treating an individual C. Emotions, coping processes, and pain 1. Section introduction a. cognitive processes mediate the link between emotion and pain. i. empirical support: study on dental patients found anxiety played role in pain expectations and pain memories 2. Does emotion affect pain? a. anxiety and stress correlate with pain i. empirical evidence of causal link between stress and headache pain - self-report studies find migraine and muscle- contraction headaches occur after heightened stress and Type A persons have more frequent chronic headaches - study with stressful task found 1/4 of occasional headache sufferers and 2/3 chronic headache sufferers developed headache during experiment - still questionable whether stress causes pain however b. pain itself is a significant stressor 3. Coping with pain a. chronic pain patients tend to use emotion-focused coping strategies (such as hoping, praying, or distraction) due to common belief of little control over pain i. these approaches not found to be effective b. research using MMPI results to explore effectiveness in dealing with pain i. three conclusions  - persons with chronic pain show high scores on hypochondriasis, depression, hysteria (the neurotic triad) yet normal scores on remaining scales - neurotic triad pattern is reflected regardless of whether there is a known organic source for pain - persons with acute pain have scores within normal range on all scales c. does chronic pain cause maladjustment? i. evidence that the answer is “yes” - persons whose pain has ended show reduction in psychological disturbance - depression is common in pain patients - helplessness leads to depression - patients begin to catastrophize d. maladjustment may also lead to pain i. depressed persons more likely to develop chronic pain condition in future e. pain and maladjustment involve interactive processes IV. Assessing People's Pain A. Section introduction 1. A variety of methods have been developed to assess pain in both research and clinical settings a. using multiple methods increases accuracy of assessment B. Self-report methods 1. Interview methods in assessing pain a. interviews are conducted with patient and family or coworkers to provide background information during early stages of treatment b. elements of the interview i. history of the pain ii. patient's emotional adjustment iii. patient's lifestyle before pain iv. impact on patient's lifestyle v. social context of the pain episodes vi. factors which trigger the pain vii. typical efforts to cope 2. Pain rating scales and diaries a. scales involve rating some aspect of pain, often the intensity of the pain b. types of pain rating scales i. visual analog scale - rating pain by placing a mark on a line with labels at the end points ii. box scale - series of numbers inside boxes that represent levels of pain intensity iii. verbal rating scale - describing pain by choosing words or phrases that reflect experience c. advantages to rating scales i. pain can be rated quickly and frequently ii. change in pain can be traced  iii. patterns of pain can be reflected iv. aspects of pain from environment can be noted and changed d. clients need to be trained to learn what to say if others see them making notes, reminding themselves to make ratings, and what to do if they forget to do a rating e. pain diaries - detailed record of person's pain experiences 3. Pain questionnaires a. McGill Pain Questionnaire i. involves ratings of words according to 20 affective, sensory, and evaluative dimensions ii. MPQ yields a pain rating index and present pain intensity iii. advantages of MPQ - empirically confirmed that pain is a multidimensional event - produced evidence that people with different pain syndromes report different symptoms iv. disadvantages of MPQ - requires strong English vocabulary - requires fine distinctions between words b. Multidimensional Pain Inventory is another, more recently developed pain assessment B. Behavioral assessment approaches 1. Section introduction a. because people exhibit pain behaviors, should be able to assess pain by observing behavior i. assume that pain behaviors vary depending on types and patterns of pain - example: if pain is intense v. moderate, a headache v. low back pain, recurrent v. intractable 2. Assessing pain behavior in structured clinical sessions a. UAB Pain Behavior Scale - nurses rate patients on ten behaviors b. videotaped performance of standard activities in structured clinical sessions i. patients rated on performance of pain behaviors (e.g., guarded movement, etc.) ii. behavioral assessments correlate with self-ratings of pain 3. Assessing pain behavior in everyday activities a. family members can be trained to observe and rate most common pain behaviors i. observations include frequency and amount of time pain behaviors demonstrated and how others react to the pain behavior b. spouse may complete a pain diary, including date/time/location of episode, behavior observed that suggested pain, assessor’s thoughts/feelings during episode, assessor’s assistance efforts  c. procedures provide additional data regarding interpersonal issues that influence pain episodes C. Psychophysiological measures 1. Psychophysiology – study of mental or emotional processes as reflected by changes they produce in physiological activity 2. Types of measures a. electromyograph (EMG) measures degree of muscle tension i. empirical results - studies find differences in EMG activity in pain/no pain patients in affected muscles when patient is physically/psychologically stressed but not during periods of inactivity - EMG findings reflect pain levels when gathered over extended period of time b. autonomic (heart rate & skin conductance) activity i. empirical results - interpreting increases in activity is difficult/not useful because autonomic activity is related more to ratings of pain rather than strength of pain stimulus, are inconsistently associated with chronic pain, and occur in absence of pain but presence of other events (e.g., stress) c. electroencephalograph (EEG) recordings – measure of electrical activity in brain i. empirical results - amplitudes increase with intensity of pain, decrease when analgesia taken, and correlate with self-report of pain d. because psychophysiological measures are affected by other factors, probably best used as supplements to self-report and behavioral assessments V. Pain in Children A. Section introduction 1. Children experience same pain conditions as adults. a. may also experience a unique form of pain referred to as "growing pains" 2. Little research was done on children prior to 1980s a. assumed nervous systems were too immature to experience pain B. Pain and children's sensory and cognitive development 1. Newborns experience pain a. evidence i. crying when spanked at birth ii. "pain" facial expressions and crying that varies during noxious medical procedures 2. Expression of pain is affected by limited language development. a. may demonstrate pain through pain behaviors such as crying, rubbing affected area, clenching jaws  b. younger children have fewer words to describe pain compared to older children C. Assessing pain in children 1. Self-report provides limited information. a. clinicians rely on interviews, behavioral and physiological assessments i. in children under 5, assessments made via behavioral observations (e.g., vocalizations, facial expressions) ii. with older children, visual analog scales and verbal rating scales can be used with faces depicting varying degrees of distress 2. Pain questionnaires for children a. questionnaires have been developed to assess pain experience and psychosocial effects on child/family i. examples: Pediatric Pain Questionnaire and Children's Comprehensive Pain Questionnaire 3. Other methods of assessment a. behavioral and physiological assessments b. pain diaries kept by child or parents c. structured clinical assessments by health care workers 4. Factors that affect children's pain experiences a. parental models and reinforcement for pain behaviors b. little known about personality and family characteristics that contribute to intensity/frequency of children’s pain experiences