7 What is pain? u Simply put, pain is usually nature’s unpleasant way of telling you that a part of your body needs your immediate attention, or that you’re using parts of your body beyond their limits.
8 What Is Pain? u Clinical Pain –Pain that requires some form of medical treatment u Most people experience an average of 3 to 4 different kinds of pain each year u Pain is the most common reason people seek medical treatment u Annual costs may reach $100 billion
Acute versus chronic pain u Acute pain is ordinarily beneficial: it warns that something is wrong. u Chronic pain never has a biological benefit.
11 40 Million Americans suffer from chronic pain such as: u Lower back problems u Arthritis u Cancer u Repetitive stress injuries u Migraine headaches
12 What percent of Americans suffer chronic pain? A. 5% B. 13% C. 30% D. 50% E. 80%
13 What percent of Americans suffer chronic pain? A. 5% B. 13% C. 30% D. 50% E. 80%
14 What is the current population of America? u 50 million u 100 million u 150 million u 300 million u 1 billion
Subdivisions of the vertebrate nervous system u Central Nervous System – Brain – Spinal Cord u Peripheral Nervous System – All neurons outside the brain and spinal cord are part of the peripheral nervous system
Peripheral Nervous System u Somatic nervous System – Sensory Neurons (afferent) – Motor Neurons (efferent) u Autonomic Nervous System » Sympathetic division » Parasympathetic division
17 The Meaning of Pain u Pain sometimes thought to be a direct consequence of physical injury.
18 Specificity Theory of Pain u Specific pain fibers and pathways exist u Pain = tissue damage
19 Nociception u is the sensation of pain in normal people
20 The perception of pain u Not a direct relationship between tissue damage and the perception of pain. u Personal perception mediates the experience of pain.
21 Suffering u An affective or emotional response triggered by a nociceptive-pain event or some other aversive stimulus.
22 u Pain due to two factors: –The sensation (Nociception) –The individual’s reaction to that sensation
26 Nociception u Nociceptive u Of, causing or reacting to pain. u Definitions of pain in terms of tissue damage relay on known physiology of the body’s pain sensors (free nerve endings called nociceptors) and neural transmission of pain signals to the CNS, a process called nociception.
Pain chemistry u Prostaglandins, chemicals released by damaged tissue and involved in inflammation. u Pain is produced by neurons that must be energized via neurotransmitters.
28 The Physiology of Pain u Unlike other senses, pain is not triggered by only one type of stimulus, nor does it have a single type of receptor u Free Nerve Endings — sensory receptors found throughout the body that respond to temperature, pressure, and painful stimuli u Nociceptor — a specialized neuron that responds to painful stimuli
29 The Physiology of Pain u Fast Nerve Fibers –Large, myelinated nerve fibers that transmit sharp, stinging pain u Slow Nerve Fibers –Small, unmyelinated nerve fibers that carry dull, aching pain
Measuring Pain u There are no objective measures of pain. 31
32 Measuring Pain u Psychophysiological Measures –Psyche (mind) – physike (body) –Electromyography (EMG) — assess the amount of muscle tension experienced by pain sufferers –Indicators of autonomic arousal — using measures of heart rate, breathing rate, blood pressure, etc
33 Measuring Pain u Behavioral Measures –Pain Behavior Scale »Target behaviors include vocal complaints, facial grimaces, awkward postures, mobility
34 Measuring Pain u 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 »Pain Anxiety Symptoms Scale (PASS)
Stages of pain u Acute pain. adaptive lasts less than six months. u Prechronic pain. critical period to overcome pain. u Chronic pain endures beyond the time of healing.
Chronic Pain u Chronic recurrent pain- episodic u Chronic intractable benign pain- always present but not always severe. u Chronic progressive pain. Omnipresent u Chronic pain frequently associated with psychopathology.
Headache u 29 Million Americans suffer from sever, disabling headache u 18% of women and 7% of men report at least one migraine a year.
Muscle tension headache u Causes – stress – posture and muscle habits – lack of flexibility – lack of strength
Treating muscle-tension headache u Diaphragmatic breathing u Progressive muscle relaxation u Temperature and EMG biofeedback u Without some behavioral and cognitive coping skills training this procedure may be palliative
43 Physical Treatment of pain u Analgesic drugs relieve pain without loss of consciousness.
44 NSAIDs u Nonsteroidal anti- inflammatory drugs. u Act at the site of the injury rather than in the brain. u Have anti- inflammatory properties u Aspirin, u Ibuprofen (Advil, Motrin)
45 Tylenol (acetaminophen) u Acetaminophen has negligible anti- inflammatory activity, and is strictly speaking not an NSAID. u The medicine in Tylenol is not an NSAID. It’s a pain reliever that works differently. –http://www.tylenol.com/http://www.tylenol.com/
46 Aspirin u Known since 500 B.C. u Comes from bark of willow tree u 1899 Bayer began marketing aspirin u acetylsalicylic acid
47 NSAID’s u unlike opioids, they do not produce sedation, respiratory depression, or addiction. u They work by inhibiting an enzyme that helps produce prostaglandins.
48 Aspirin u The most popular uses of aspirin are for: – prevention of heart disease (37.6 percent), –arthritis (23.3 percent), –headache (13.8 percent), –body ache (12.2 percent) and –other pain uses (14.1 percent).
Pain treatment u Opiate drugs block pain by occupying the sites where the neurotransmitters would attach. u No other type of drug produces more complete pain relief. u Potential for addiction. u Oxycodone (Oxycontin) u Hydrocodone (Vicodin) u Morphine, Codeine,
50 Endorphins u Endorphins (endogenous morphine) naturally occurring neurochemical which work like opiates.
Chronic Pain u Pain is subjective u Secondary gains can be considerable u Pain difficult to measure u Many may be malingering u Others may be “faking” unintentionally
52 Malingering u Feigning illness or other incapacity in order to avoid duty or work
58 Vioxx u Approved in 1999 for the treatment of acute pain and chronic pain from arthritis and other problems.
59 VIOXX the Science u “Merck has always believed that prospective, randomized, controlled clinical trials are the best way to evaluate the safety of medicines.” u Prospective u Randomized u Controlled
60 VIOXX the Science u Risk of heart attack, stroke and blood clots after 18 months. –VIOXX 15 per thousand –Placebo7.5 per thousand –“Although the absolute risk may be rather small, the relative risk is high. “
61 VIOXX the market u “Marginal efficiency, heightened risk, excessive cost.” u Vioxx provides about the same relief as aspirin though patients are less likely to develop ulcers or gastrointestinal bleeding.
63 Cox-2 inhibitor u Aspirin blocks the production of prostaglandins, key hormones that are used to carry local messages. u Cyclooxygenase (cox- 1, cox-2) performs the first step in the creation of prostaglandins
66 VIOXX advertising u In the first 6 months of this year alone Merck spent $45 million advertising Vioxx. u “Terrifying testimony to the power of marketing.”
67 Health Belief Model u Beliefs contribute to behavior u Perceived: –susceptibility –severity –benefits –barriers
68 Sociocultural Factors u Culture and Ethnicity –Groups differ greatly in their response to pain –Through social learning, groups establish norms for the degree to which suffering should be openly expressed and the form that pain behaviors should take u Pain tolerance versus pain threshold
69 A Pain-Prone Personality? u Acute and chronic pain sufferers show elevated scores on two MMPI scales: –Hysteria (tendency to exaggerate symptoms and use emotional behavior to solve problems) –Hypochondriasis (tendency to be overly concerned about health and to overreport body symptoms) u Chronic pain sufferers also score high in depression
70 A Pain-Prone Personality? u Placebo responsiveness may be a situational trait rather than a dispositional trait –No consistent personality differences in placebo responders and nonresponders
71 Types of Pain Patients (Turk & Nash) u Dysfunctional patients –report high levels of pain, feel they have little control over their lives, and are extremely inactive u Interpersonally distressed patients –perceive little social support and feel other people in their lives don’t take their pain seriously u Adaptive copers –report lower levels of pain and distress and continue to function at a high level
72 Operant conditioning u Behavior –Go to the doctor u Consequence –Pain of a shot added u Behavior tends to decrease
73 Generous sick leave u Two and a half years later, she is still on government-paid sick leave, resting at her comfortable home.
74 u with breaks for stretching drills in her living room, restorative walks through pine woods and the occasional round of golf.
75 Malingering u 62 percent of the employees interviewed said they had taken sick leave when they were not really sick and that they felt there was nothing wrong in doing so.
76 Doctor’s excuse u physicians routinely approve sick leaves solely at a patient's request. u "It takes 30 seconds to write a doctor's note, It can take an hour to convince someone that he is ready to go back to work, and meanwhile your waiting room is filling up."
77 Correlation u In 1998, the government's benefit increased from 75 percent to 80 percent of salary, and the average number of days spiked upward each year thereafter, from 11.1 in 1997 to 24.4 in 2001.
78 u Employees get time off when they want it u Employers gain a way of moving underperforming workers u The government can claim one of the lowest rates of unemployment
79 Somatoform Pain disorder u Significant pain u Presumed psychological factors play a role in course u Not due to malingering or factitious disorder.