1. Chronic Pain Dr. MC Chu Anaesthesia and Intensive Care PWH

2. Agenda • Start at acute pain • Un-veil the complexity of chronic pain • In second part we will try to treat them

3. Let’s start with acute pain • Tissue damage • Site and intensity correlation • Gets better with healing (self limiting)

4. Case 1 • A man with a pain in his right leg • “Are you sure it is the right leg?”

5. Case 1 • A man with a pain in his right leg • How does it feel like?

6. Case 1 • A man with a pain in his right leg • And any other abnormalities?

7. Case 1 • A man with a pain in his right leg • What causes it?

8. Remarks from Case 1 • Chronic pain is not prolonged acute pain

9. Remarks from Case 1 • Pathophysiology is different from acute pain • Sensitization • Reduced pain threshold (hyperalgesia) • Non-painful stimulus (allodynia)

10. Remarks from Case 1 • Pathophysiology is different from acute pain • Neuropathic pain • Site • Character • Timing • More than that…

11. Case 2 • A man with fracture forearm, compartment syndrome • Fracture fixed, fasciotomy healed • Neurovascular integrity OK • But he has pain and other things

12. Case 2 • A man with fracture forearm, compartment syndrome • What else do you noticed?

13. Case 2 • A man with fracture forearm, compartment syndrome • What are the differentials?

14. Case 2 • A man with fracture forearm, compartment syndrome • He want to chop his forearm off. Useful?

15. 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…

16. Case 3 • A lady with difficulty in her dress • Diagnosis?

17. Case 3 • A lady with difficulty in her dress • Does physiotherapy help?

18. Case 3 • A lady with difficulty in her dress • Does topical therapy help?

19. Case 3 • A lady with difficulty in her dress • Does NSAID help?

20. Case 3 • A lady with difficulty in her dress • Does opioids help?

21. 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…

22. King Mongkut • Lung cancer with pain in his chest, arm and abdomen

23. Case 4 • Lung cancer with pain in his chest, arm and abdomen • Why does he has a chest pain?

24. Case 4 • Lung cancer with pain in his chest, arm and abdomen • Why does he has an arm pain?

25. Case 4 • Lung cancer with pain in his chest, arm and abdomen • Why does he has an abdominal pain?

26. Case 4 • Lung cancer with pain in his chest, arm and abdomen • What bother him most?

27. 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…

28. Ms. Unhappy Why can’t you fix my neck and fxxk off

29. Ms. Unhappy • 33 year old woman, traffic accident • “whiplash injury” • MRI: unremarkable Nociception

30. Ms. Unhappy • She felt so bad that he cannot sleep, cannot eat, and became irritable Affect

31. Ms. Unhappy • She cannot work, cannot go out, cannot do housework, cannot…. Social

32. Ms. Unhappy • She insisted to use a neck collar, visited 4 doctors for the “right diagnosis”, alcohol to “knock me off the pain” Behavior

33. 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

34. Want to have a break?

35. 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

36. Chronic pain as a disease • Impact of chronic pain • Elliott et al Lancet 1999

37. 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

38. 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?

39. Chronic pain as a disease • How much is this? • Cost: 7 billion US$

40. Chronic pain as a disease • How much is this? • Cost: 4 million US$ per year

41. Chronic pain as a disease • Impact of chronic pain White et al J. Occu. & Environ. Med. 2005

42. Clinical aspect

43. Scope of pain medicine • Etiology • Trauma (including iatrogenic) • Cancer (and its treatment) • Infections / inflammations • Mechanical / functional • Idiopathic

44. Scope of pain medicine • Etiology • Trauma (including iatrogenic) • Cancer (and its treatment) • Infections / inflammations • Mechanical / functional • Idiopathic

45. Scope of pain medicine • Complex Regional Pain Syndrome (CRPS) • Type I and II (with obvious nerve injury) • Which type is this one?

46. 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

47. Scope of pain medicine • Persistent post-operative pain • Bay-Nielson Annals of Surgery 2001

48. 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

49. Scope of pain medicine • Etiology • Trauma (including iatrogenic) • Cancer (and its treatment) • Infections / inflammations • Mechanical / functional • Idiopathic

50. Scope of pain medicine • Cancer pain • Over 50% cancer patients have severe pain at their end • What contribute to this un-desirable outcome?