Unraveling the Mystery of Chronic Pain John D. McKellar, PhD Department of Veteran Affairs and Stanford University

Understanding Chronic Pain Acute versus Chronic Pain Specificity Theory Gate Control Theory Additional factors that influence pain

Acute vs Chronic Pain ACUTE CHRONIC A warning sign Time-limited, diminishes as healing occurs Cause usually known, identifiable CHRONIC False alarm, not a signal of injury Persists beyond 90 days, expected healing Observable physiological signs may be absent

Theories of Pain Pain is basic to human experience Provider’s theories about pain are primarily based upon the provider’s experience The challenge for pain theory is to account for wide variety of human pain experiences

Specificity Theory Oldest theory of pain, physical pathology = pain Rene Descartes Pain Illustration 1644

Specificity Theory Pain Intensity = Physical Pathology Pain Center Site of Injury Spinal Cord Pain Intensity = Physical Pathology No Additional Influences Oldest theory and still the most widely held by patients and providers

Specificity Theory Limitations Many people continue to experience pain well after an injury has healed. People with identical injuries report vastly different levels of pain. Subjects in experimental pain studies report vastly different levels of pain to the same stimulus.

Specificity Theory Negative consequences Providers question patient’s report of pain when they cannot see evidence of damage Patients assume that the presence of pain indicates that something is very wrong (which increases pain perception)

Gate Control Theory Pain perception is a function of sensory input from the body (ascending pathways) and perceptions from the brain (descending pathways). The “gate” is located within the spinal cord (dorsal horn) and involves input from body and brain operating simultaneously- the gate opens or closes. Factors that open the gate increase pain, factors that close the gate decrease pain- as with a volume knob.

Gate Control Theory Site of Injury Gate (open/closed) Emotion Center Pain Center Emotion Center Thought Center Site of Injury

Gate Control Theory Factors that Open the Gate Negative Emotions Depression, anxiety, stress Negative Thoughts “I can’t take this pain anymore” Focusing Attention on Pain Absence of pleasant activities, unemployment

Gate Control Theory Factors that close the gate Positive emotions States of Relaxation Guided imagery, Meditation, Yoga, etc. Attention directed away from pain Recreational activities, positive distraction, etc

Gate Control Theory Site of Injury Situation/ Behavior/ Physical State (open/closed) Pain Center Emotion Center Thought Center Site of Injury Situation/ Behavior/ Physical State Thoughts Emotions

Gate Control Theory Example #1 Opening the Gate Two patients attend a dental appointment…..

Gate Control Theory Closing the Gate Example: An offensive lineman on the SF 49ers was seen rolling on the ground in pain at the close of a play….

The Gate Control Theory provides us with ways to help patients “turn down the volume” on their pain!!

BioPsychoSocial Model of Pain Environmental/Social Factors Pain Responses Psychological Biological Behavioral/Social

Biopsychosocial Variables Associated with Chronic Pain:

Beliefs About Pain Hurt vs. Harm – Pain as a Mystery – Pain Self-Efficacy –

Catastrophizing Catastrophic thoughts involve thinking the worst about pain or its implications “this will go on forever,” “my pain will never stop,” or “nothing can be done to improve my pain.” Extremely prevalent and problematic, BUT appears to decrease in response to CBT-CP.

Avoidance Avoidance of activities and people is a hallmark symptom of CP “Disuse syndrome” Avoidance of social or recreational activities can lead to isolation and depression

Fear or Movement/Re-Injury Onset of Pain Painful experiences Fear of movement or injury Avoidance Disability Disuse Depression No Fear Approach Recovery Catastrophizing

Solicitous Loved One Individuals highly responsive to a patient’s pain/pain behaviors actually increase a patient’s level of pain (compared to spouses/partners who suggest helpful but distracting ways to cope with pain) If demonstrations of increased pain garner additional attention/assistance, there may also be secondary gains Solicitous Spouse Study-

Social Constraints If “solicitousness” is at one end of a social dimension then “constraint” is at the other Social Constraint involves preventing expression about health problems such as pain This can happen from significant others or from providers

Summary Acute versus Chronic Pain Specificity Theory Gate Control Theory Additional factors that influence pain: thoughts, behaviors, social