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Chronic Pain. Dr. MC Chu Anaesthesia and Intensive Care PWH. Agenda. Start at acute pain Un-veil the complexity of chronic pain In second part we will try to treat them. Let’s start with acute pain. Tissue damage Site and intensity correlation Gets better with healing (self limiting).
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Chronic Pain Dr. MC Chu Anaesthesia and Intensive Care PWH
Agenda • Start at acute pain • Un-veil the complexity of chronic pain • In second part we will try to treat them
Let’s start with acute pain • Tissue damage • Site and intensity correlation • Gets better with healing (self limiting)
Case 1 • A man with a pain in his right leg • “Are you sure it is the right leg?”
Case 1 • A man with a pain in his right leg • How does it feel like?
Case 1 • A man with a pain in his right leg • And any other abnormalities?
Case 1 • A man with a pain in his right leg • What causes it?
Remarks from Case 1 • Chronic pain is not prolonged acute pain
Remarks from Case 1 • Pathophysiology is different from acute pain • Sensitization • Reduced pain threshold (hyperalgesia) • Non-painful stimulus (allodynia)
Remarks from Case 1 • Pathophysiology is different from acute pain • Neuropathic pain • Site • Character • Timing • More than that…
Case 2 • A man with fracture forearm, compartment syndrome • Fracture fixed, fasciotomy healed • Neurovascular integrity OK • But he has pain and other things
Case 2 • A man with fracture forearm, compartment syndrome • What else do you noticed?
Case 2 • A man with fracture forearm, compartment syndrome • What are the differentials?
Case 2 • A man with fracture forearm, compartment syndrome • He want to chop his forearm off. Useful?
Remarks from Case 2 • Impairment is different from acute pain • Pain can come without obvious pathology • Pain, motor, sudomotor or sensory changes • Trophic changes • Exclude differentials • One more example…
Case 3 • A lady with difficulty in her dress • Diagnosis?
Case 3 • A lady with difficulty in her dress • Does physiotherapy help?
Case 3 • A lady with difficulty in her dress • Does topical therapy help?
Case 3 • A lady with difficulty in her dress • Does NSAID help?
Case 3 • A lady with difficulty in her dress • Does opioids help?
Remarks from Case 3 • Treatment are different from acute pain • Partial response to “common” analgesics • Long term side effects • Tolerances, organ damages • Not all chronic pains are neuropathies…
King Mongkut • Lung cancer with pain in his chest, arm and abdomen
Case 4 • Lung cancer with pain in his chest, arm and abdomen • Why does he has a chest pain?
Case 4 • Lung cancer with pain in his chest, arm and abdomen • Why does he has an arm pain?
Case 4 • Lung cancer with pain in his chest, arm and abdomen • Why does he has an abdominal pain?
Case 4 • Lung cancer with pain in his chest, arm and abdomen • What bother him most?
Remarks from Case 4 • Pain is common source of distress • Multiple etiologies • Iatrogenic • Other somatic symptoms • Other psychosocial factors • Role of palliative medicine • Now, the classical onion…
Ms. Unhappy Why can’t you fix my neck and fxxk off
Ms. Unhappy • 33 year old woman, traffic accident • “whiplash injury” • MRI: unremarkable Nociception
Ms. Unhappy • She felt so bad that he cannot sleep, cannot eat, and became irritable Affect
Ms. Unhappy • She cannot work, cannot go out, cannot do housework, cannot…. Social
Ms. Unhappy • She insisted to use a neck collar, visited 4 doctors for the “right diagnosis”, alcohol to “knock me off the pain” Behavior
Remarks from Case 5 • Multi-facet problems of chronic pain • Nociception is different • Mood is altered • Behavior and thoughts are changed • Function is impaired • They are a different person altogether • Chronic pain is a disease of its own • Pain Management is a specialty of its own
Chronic pain as a disease • Definitions • “Pain extending for a long period of time, represents low levels of underlying pathology that does not explain the presence and extent of pain, or both” • Turk in: Bonica’s Management of Pain 3rd Ed. • “Pain without apparent biological value that persists beyond normal tissue healing (usually taken to be 3 months)” • IASP 1986
Chronic pain as a disease • Impact of chronic pain • Elliott et al Lancet 1999
Chronic pain as a disease • Impact of chronic pain • 10.8% of local adult Chinese • 38% work affected • 34% daily activities affected • 30% on long term analgesics • Ng et al Clin. J. Pain 2002
Chronic pain as a disease • Impact of chronic pain • 38 Billion Euro per year in Germany • 62 Billion US$ per year in US • Zimmermann Orthopade 2004 • Steward et al JAMA 2003 • How much is this?
Chronic pain as a disease • How much is this? • Cost: 7 billion US$
Chronic pain as a disease • How much is this? • Cost: 4 million US$ per year
Chronic pain as a disease • Impact of chronic pain White et al J. Occu. & Environ. Med. 2005
Scope of pain medicine • Etiology • Trauma (including iatrogenic) • Cancer (and its treatment) • Infections / inflammations • Mechanical / functional • Idiopathic
Scope of pain medicine • Etiology • Trauma (including iatrogenic) • Cancer (and its treatment) • Infections / inflammations • Mechanical / functional • Idiopathic
Scope of pain medicine • Complex Regional Pain Syndrome (CRPS) • Type I and II (with obvious nerve injury) • Which type is this one?
Scope of pain medicine • Complex Regional Pain Syndrome (CRPS) • Pathophysiology is unknown • Diagnosis is clinical • Investigations are not diagnostic • Treatment is empirical • Prognosis: 30% loss of work at 1 year • “early intervention to prevent disability” • Atkins J. Bone & Joint Surg 2003
Scope of pain medicine • Persistent post-operative pain • Bay-Nielson Annals of Surgery 2001
Scope of pain medicine • Persistent post-operative pain • Predictive factor: intensity of early post-op. pain • Most will resolve slowly • Is it preventable? • Role of pre-emptive analgesia still uncertain • Should be part of the surgical consent
Scope of pain medicine • Etiology • Trauma (including iatrogenic) • Cancer (and its treatment) • Infections / inflammations • Mechanical / functional • Idiopathic
Scope of pain medicine • Cancer pain • Over 50% cancer patients have severe pain at their end • What contribute to this un-desirable outcome?