What is Chronic Pain? Lori Montgomery MD CCFP Clinical Lecturer, Departments of Family Medicine and Anesthesia Medical Director, AHS Chronic Pain Centre

Disclosures Grants/Research Support: None Speakers Bureau/Honoraria: None Consulting Fees: None

290,000 (11.2%) experience chronic pain. 190,000 (7.5%) experience severe chronic pain. Alberta Health data based on 1996 National Population Health Survey and 2001 Canadian Community Health Survey Prevalence in Alberta

3–4%

Robin Low back pain for 12 years Gradual onset Two low-velocity MVCs, each made pain a bit worse No red flags Physical exam: reduced range of motion and strength; neuro exam normal; no radicular signs

Robin Visits you every few weeks, looking for something to make the pain go away This visit, Robin is very angry: “Just tell me why my back hurts!”

Pain "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” International Association for the Study of Pain

A model of acute pain Predictable Associated with tissue damage Circuitry well defined Self limiting Unimodal treatment Responds predictably Useful warning function

BUT The relationship between injury and pain is NOT 1 to 1

Relationship between Tissue Damage and Pain Acute injury may not be associated with pain

Henbit, Epsom Derby,UK

Relationship between Tissue Damage and Pain Pain may not be associated with acute injury

A model of chronic pain Unpredictable Relationship with tissue damage unclear Circuitry complex Continues Multimodal treatment Difficult to treat No useful warning function

PAIN PERCEPTION The mind and the body“ Rene Descartes “spino-thalamic tract”

Tissue damage Inflammation Nerve compression 5-HT, Bradykinin, Cytokines, Histamine, Prostaglandins The Chemistry of Pain EAAs  NMDA receptors SubP / NGF / NK1 / CGRP / NO Neuronal Plasticity Descending Excitation /Inhibition Dynorphin A / CCK 5HT / NE / GABA Attention Expectation Affect Peripheral  Sensitization  Central

“Explaining Pain”

Pain experience Balance of input with modulation Genetics Environment Beliefs Mood Social response See Lorimer Mosely video

Pain is an alarm

Credible evidence

But why does it persist?

Pain Pathways Firing & Wiring Dirt RoadSuper Highway NMDAR

Fibromyalgia: from pathophysiology to therapy, Tobias Schmidt-Wilcke & Daniel J. Clauw, Nature Reviews Rheumatology 7, (September 2011)

Chronic Pain after surgery

Nociceptive Pain

Postherpetic Neuralgia: Clinical Features Sensory Loss And Allodynia Allodynia Sensory Loss Scarring

Lumbar vertebra Disc herniation Activation of peripheral nociceptors – cause of nociceptive pain component Compression and inflammation of nerve root – cause of NeP component Herniated disc causing low back pain and lumbar radiculopathy Example of Mixed Pain “Mixed” or “combined” pain requires a broader therapeutic approach to relieve both pain components

Visceral Pain

Myofascial Pain

FMS & Widespread Pain Low Serum Cortisol - abnormal Pituitary adrenal axis (poor stress response) Altered Growth Hormone secretion Low Serotonin in plasma and CSF High CSF level of Substance P, NGF Gene polymorphism Central sensitization

Robin Visits you every few weeks, looking for something to make the pain go away This visit, Robin is very angry: “Just tell me why my back hurts!”

Pain and disability

Model of Disability Main & Spanswick Injury Pain Main & Spanswi c k, 2000

Injury Pain Physical deconditioning Withdrawal From work & Soc activities Reduced physical activities Main & Spanswi c k, Development of deconditioning and disuse Model of Disability Main & Spanswick Guarded movements and muscle spasm

Injury Pain Pateint‘s (mis)-attributions Fear avoidance Main & Spanswi c k, Development of deconditioning and disuse 2. Influence of fear and avoidance Physical deconditioning Withdrawal From work & Soc activities Reduced physical activities Model of Disability Main & Spanswick Guarded movements and muscle spasm

Injury Pain Focus on symptoms Learned helplessness (Depression) Physical deconditioning Withdrawal From work & Soc activities Pateint‘s (mis)-attributions Reduced physical activities Fear avoidance Main & Spanswi c k, Development of deconditioning and disuse 2. Influence of fear and avoidance 3. Influence of depression Model of Disability Main & Spanswick Guarded movements and muscle spasm

Injury Pain Focus on symptoms Learned helplessness (Depression) Physical deconditioning Withdrawal From work & Soc activities Pateint‘s (mis)-attributions Treatment (failed) Reduced physical activities Anger, Frustration Fear avoidance Main & Spanswi c k, Development of deconditioning and disuse 2. Influence of fear and avoidance 3. Influence of depression 4. Influence of anger and frustration Model of Disability Main & Spanswick Guarded movements and muscle spasm

Injury Pain Focus on symptoms Learned helplessness (Depression) Physical deconditioning Withdrawal From work & Soc activities Pateint‘s (mis)-attributions Treatment (failed) Reduced physical activities Anger, Frustration Fear avoidance Main & Spanswi c k, 2000 IATROGENICSIATROGENICS IATROGENICSIATROGENICS 1. Development of deconditioning and disuse 2. Influence of fear and avoidance 3. Influence of depression 4. Influence of anger and frustration 5. Influence of iatrogenics Model of Disability Main & Spanswick Guarded movements and muscle spasm

Injury Pain Focus on symptoms Learned helplessness (Depression) Physical deconditioning Withdrawal From work & Soc activities Pateint‘s (mis)-attributions Treatment (failed) Reduced physical activities Anger, Frustration Fear avoidance Main & Spanswi c k, 2000 Family IATROGENICSIATROGENICS IATROGENICSIATROGENICS 1. Development of deconditioning and disuse 2. Influence of fear and avoidance 3. Influence of depression 4. Influence of anger and frustration 5. Influence of iatrogenics 6. Influence of the family Model of Disability Main & Spanswick Guarded movements and muscle spasm

Injury Pain Focus on symptoms Learned helplessness (Depression) Physical deconditioning Withdrawal From work & Soc activities Patient‘s (mis)-attributions Socioeconomics Litigation/benefits Treatment (failed) Reduced physical activities Anger, Frustration Fear avoidance Main & Spanswi c k, 2000 Family IATROGENICSIATROGENICS IATROGENICSIATROGENICS 1. Development of deconditioning and disuse 2. Influence of fear and avoidance 3. Influence of depression 4. Influence of anger and frustration 5. Influence of iatrogenics 6. Influence of the family 7. Influence of socioeconomic and occupational factors Model of Disability Main & Spanswick Guarded movements and muscle spasm