Chronic

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?

51. Scope of pain medicine
Cancer pain
Difficulties with treatment
Side effects may be intolerable
Oral intolerance
Fatigue or impaired consciousness

52. Scope of pain medicine
Cancer pain
Difficulties with treatment
Patients and doctors refuse treatment
Denial of disease progression
Hope of curing the incurable
Myths of analgesics, including addiction
“Opio-phobia”

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

54. Scope of pain medicine
Acute low back pain
Leading cause for GP consultations
Most (>90%) gets better in 2 weeks
Blind investigation yield is very low (< 5%)
How many of you have this?

55. Scope of pain medicine
Acute low back pain
Most important: to exclude organic pathology
“Red flags”
Fever
History of trauma
Constitutional (weight / appetide loss)
Neurological (cauda equina /radiculopathy)
Non-spine pathology eg: pulsatile abdominal mass

56. Scope of pain medicine
Acute low back pain
Most important: to exclude organic pathology
“Red flags”

57. Scope of pain medicine
Acute low back pain
NSAID, paracetamol
Avoid opioids / muscle relaxants
Avoid aggressive physio
Avoid bed rest
Live a normal life

58. Scope of pain medicine
Acute low back pain
Predictive of chronicity and disability
“Yellow flag”
Fear avoidance behavior
Negative belief that pain is harmful or disabling
Excessive focusing on pain
Expectation on passive pain management
Linton Spine 2000

59. Scope of pain medicine
Acute low back pain
Predictive of chronicity and disability
“Yellow flag”
Depressed mood, social withdrawal
Co-existing financial and social problems
Poor job satisfaction
Linton Spine 2000

60. Scope of pain medicine
Chronic low back pain
We all pay if pain allowed to progress

61. Scope of pain medicine
Chronic low back pain
Structures potentially involved
Bone, disc, facet joints, ligaments, muscle, nerves
How can we tell?

62. Scope of pain medicine
Chronic low back pain
Musculoskeletal Examination k value
Tenderness 0.24
Muscle spasm < 0.2
Deyo JAMA 1992

63. Scope of pain medicine
Chronic low back pain
Neurological Examination k value
Weak ankle dorsiflexion 1.0
Normal ankle reflexes 0.39
Straight leg raising 0.6
Deyo JAMA 1992

64. Scope of pain medicine
Chronic low back pain
Non-organic signs
“find ways of predicting surgical failure to treat back pain”
8 physical signs associated with higher personality score
abnormalities, multiple surgeries and surgeon’s
suspicion.
Waddell 1980

65. Scope of pain medicine
Chronic low back pain
Non-organic signs
Non-anatomical motor / sensory loss
Superficial / non-anatomical tenderness
Simulation (pelvic rotate, axial load, distraction SLR)
Over-reaction
3 out of 8

66. Scope of pain medicine
Chronic low back pain
Mis-interpretation of non-organic signs
Malingering
Secondary gain
Exclude pathology
False positives

67. Scope of pain medicine
Chronic low back pain
Investigations
Poor correlation with imaging findings
This is obvious

68. Scope of pain medicine
Chronic low back pain
Investigations
Poor correlation with imaging findings
This is less obvious

69. Scope of pain medicine
Chronic low back pain
Investigations
Diagnostic nerve / joint blocks
Under-utilized

70. Scope of pain medicine
Chronic low back pain
Surgery is indicated if
Failed conservative treatment
Demonstrable pathology
Correlation with clinical findings
Minimal psychosocial complications
Why are we so cautious?

71. Scope of pain medicine
Chronic low back pain
Failed back surgery syndrome (FBSS)
More MRI, more surgery
Therefore…

72. Scope of pain medicine
Chronic low back pain
Failed back surgery syndrome (FBSS)
Fritsch Spine 1996

73. Try this one
37 year old kindergarten teacher
Sprained her back while lifting a child 2 years ago
Seen GP and several Orthopediac surgeons
Had a few spine X-rays and an MRI
“Bone spurs everywhere”
Scheduled for spinal fusion
Patient next bed: “I have that 3 times, and I’m still here”
You are consulted: “for better analgesics”

74. Try this one
37 year old kindergarten teacher
How would you assess her?
Any “better analgesic” to offer?

75. We will split the onion next time