Chronic Pain Again
Dr. MC Chu Anaesthesia and Intensive Care PWH
Agenda
Remember the cases last time? Bear in mind the complexity of chronic pain
Let’s try to treat them
Treatment principles
Pain as a symptom Find the cause and fix it Pathology oriented Works well in acute pain Well accepted by patient and doctor
Treatment principles
Pain as a symptom Find the cause and fix it
Works well here
Treatment principles
Pain as a symptom Find the cause and fix it
Does all headaches have a pathology?
Treatment principles
Pain as a symptom Control the symptom Passive Long term effects and side effects Case specific What are the options?
Symptom control
Medications Antipyretics (paracetamol) NSAID Opioids Antidepressants Anticonvulsants Steroids, muscle relaxants, etc.
Symptom control
Paracetamol Effective in OA knees Amadio Curr. Ther. Res. 1983 Effectiveness ~ Ibuprofen Bradley N. Eng. J. Med. 1991 Safe and economical, NSAID sparing for elderly Nikles Am. J. Ther. 2005
Symptom control
Paracetamol Evidence in OA only Hepatic and renal toxicity do occur Medication induced headache
Symptom control
Medications Antipyretics (paracetamol) NSAID Opioids Antidepressants Membrane stabilisers (anticonvulsants) Steroids, muscle relaxants, etc.
Symptom control
NSAID Best evidence from rheumatoid arthritis Also good for cancer pain Effective in 5 out of 10 placebo-trials for LBP Effective in 4 out of 9 Panadol-trials for LBP Doubtful value for non-specific musculoskeletal pain Koes Ann. Rheum. Dis. 1997 Eisenberg J. Clin. Onco. 1994
Symptom control
NSAID Annual GI bleed risk: 0.8-18% / year Annual death rate: 0.03-0.1% / year
MacDonald BMJ 1997
Symptom control
NSAID Risk increase with age, > 4 week use, history of GI bleed / ulcer / CVS disease
Least damaging: Ibuprofen Only effective prophylaxis: PPI
Yeomans N. Eng. J. Med. 1998
Symptom control
COX-2 specific NSAID
You know what happened to your patients
Symptom control
COX-2 specific NSAID
You know what happened to your shares?
Symptom control
Medications Antipyretics (paracetamol) NSAID Opioids Antidepressants Membrane stabilisers (anticonvulsants) Steroids, muscle relaxants, etc.
Symptom control
Opioids Gold standard for cancer pain management (mostly) cheap and readily available
Administered at every route
Symptom control
Opioids Controversial for non-cancer pain Limited (but positive) evidence of efficacy Extensive side effects Tolerance Dependence Divergence
Symptom control
Opioids Controversial for non-cancer pain
“Physicians should make every effort to control indiscriminate prescribing, even under pressure from patients…” Ballantyne N. Eng. J. Med. 2003
Symptom control
Opioids Controversial for non-cancer pain
“Opioids are our most powerful analgesics, but politics, prejudice, and our continuing ignorance still impede optimum prescribing” McQuay Lancet 1999
Symptom control
Opioids Practical guidelines for non-cancer pain Exhaust other methods Aim at functional improvement Limit prescription authority, monitor behavior Slow release, avoid injectables Opioid contract
Symptom control
Medications Antipyretics (paracetamol) NSAID Opioids Antidepressants Membrane stabilisers (anticonvulsants) Steroids, muscle relaxants, etc.
Symptom control
Antidepressants Analgesic at below mood altering doses
NNT for diabetic neuropathy ~ 3.4 Collins J. Pain & Sym. Manag. 2000
Symptom control
Antidepressants Analgesic at below mood altering doses
NNT for post-herpetic neuralgia ~ 2.1 Collins J. Pain & Sym. Manag. 2000
Symptom control
Antidepressants How good is NNT of 2.1 to 3.4?
It is not good for this
Symptom control
Antidepressants How good is NNT of 2.1 to 3.4?
It is really good for pain
Symptom control
Antidepressants Major problem: side effects NNH (minor) ~ 2.7
No consensus which one is best Classically TCA SSRI: seemed more specific on mood
Symptom control
Medications Antipyretics (paracetamol) NSAID Opioids Antidepressants Membrane stabilisers (anticonvulsants) Steroids, muscle relaxants, etc.
Symptom control
Anticonvulsants Carbamazepime for trigeminal neuralgia
NNT ~ 2.6 NNH ~ 3.4
Symptom control
Anticonvulsants
NNT for diabetic neuropathy (red) ~ 2.7 NNT for post-herpetic neuralgia (white) ~ 3.2 Collins J. Pain & Sym. Manag. 2000
Symptom control
Anticonvulsants Gabapentin
Less organ damage No drug interaction
Want to have a break?
Symptom control
Intervention Nerve / joint block Counter-stimulation
Symptom control
Nerve block
Where to cut How to cut What is left behind
Symptom control
Nerve block
Where to cut How to cut What is left behind
Symptom control
Nerve block
Where to cut How to cut What is left behind
Symptom control
Nerve block
Where to cut How to cut What is left behind
Symptom control
CNS nerve block
Physically protected, relatively immobile Synapses are chemically vulnerable Effects (and side effects) are wide spread
Symptom control
Peripheral nerve block
Thick bundles of conducting cables Mobile, difficulties with catheters Impairment is profound yet localised
Symptom control
Visceral nerve block Contain visceral pain fibres Usually deep seated Anatomically diffuse l Visceral functions . k
Symptom control
Nerve block in chronic non-cancer pain
Preferably purely sensory block Chemical / thermal neurolysis Minimal dysfunction
Symptom control
Nerve block in chronic cancer pain
Cover most abdominal viscera 90% good to excellent relief Eisenberg et al A&A 1995
Symptom control
Joint block
Symptom control
Joint block
Symptom control
Transcutaneous Electrical Nerve Stimulation (TENS) Product of Gate theory Better than placebo in short term Minimal side effects No long term benefit
Symptom control
Spinal cord stimulation
Patient controlled No medication Permanent (almost)
Symptom control
Spinal cord stimulation
Symptom control
Spinal cord stimulation Failed back surgery Isolated neuropathy
Ischemic heart disease Peripheral vascular disease
Pain relief as a therapy
Symptom control
Spinal cord stimulation
de Jongste et al Br Heart J 1994
Symptom control
Spinal cord stimulation
How does it compare with the “golden standard”?
Symptom control
Angina attacks per week Preop CABG (51) 16.2 Post-op 5.2 p-value <0.001
SCS (53)
14.6
4.4
<0.001
Mannheimer et al Circulation 1998
Symptom control
6-months cardiac mortality and morbidity Mortality 7 Morbidity 7 Stroke 8
CABG (51)
SCS (53)
1
7
2
Mannheimer et al Circulation 1998
Symptom control
Spinal cord stimulation Only suitable for smart patients Technical expertise and follow up facilities
Complications do occur
Symptom control
Spinal cord stimulation
Cost: $ 80,000 HKD
Would you take it?
Treatment principles
Pain as a symptom Find the cause and fix it Symptomatic control
Pain as a disease
How is this disease like?
Pain as a disease
Depression Insomnia
Socially deprived
Pain Think negative In-activity
Medical Dependence
Pain as a disease
Our contribution “Degenerative” “Bone spurs” “Nothing wrong” “It is in your mind”
Pain as a disease
Our contribution
Misunderstanding on Waddell’s signs esp. malingering Incorrect attempts to test for placebo e.g. saline test
Pain as a disease
Need a multi-disciplinary approach Clinical psychology Physiotherapy Occupational therapy Nursing Social work / vocational training
Pain as a disease
Need a multi-disciplinary approach
Pain as a disease
Alleviate their depression Motivate them to mobilise despite pain Encourage active coping Reduce dependency on medical input
Stop searching for a cause Stop giving analgesics together with side effects
Cognitive behavioral therapy
Pain as a disease
Cognitive behavioral therapy Pain intensity (VAS)
9 8 7 6 5 4 3 2 1 0 Pre Post
Pain as a disease
Cognitive behavioral therapy Depression (HADS)
20
15 Pre Post
10
5
0
Pain as a disease
Cognitive behavioral therapy Catastrophising (PCS)
60 50 40 30 20 10 0 Pre Post
Pain as a disease
Cognitive behavioral therapy 40 meter carrying load (pounds)
12 10 8 6 4 2 0 Pre Post
Pain as a disease
Cognitive behavioral therapy Analgesic consumption (types)
3 2.5 2 1.5 1 0.5 0 Pre Post
Pain as a disease
Cognitive behavioral therapy Pain is the same, but More active Less depressed Less doped
Before we move on to the last bit
Pain as a specialty
Anaesthesia and pain
Expertise in peri-operative pain relief Analgesics Regional nerve blocks
Pain as a specialty
Anaesthesia and pain
Dr. John J. Bonica “Father of pain medicine”
Pain as a specialty
Getting established
IASP and its 65 global chapters Over 300000 members of multiple specialties
Pain as a specialty
Anaesthesiology Orthopediac surgery Neurosurgery Oncology / palliative care Neurology Rheumatology Rehabilitative medicine Psychiatry Radiology
Pain as a specialty
… is to specialize in everthing!
Pain as a specialty
Opportunity to work with other doctors
Pain as a specialty
Other activities
Pain as a specialty
Training
Diploma in Pain Management (HKCA) Fellowship in Pain Medicine (ANZCA)
Pain as a specialty
Pain centres at HK (2006) AHNH QEH QMH PWH UCH PYNEH
Smaller scale ones at DK, PM, etc.
Resources for you
Internation Association for the Study of Pain
www.iasp-pain.org
HK College of Anaesthesiologists
www.hkca.edu.hk
Oxford pain Internet site
www.jr2.ox.ac.uk/bandolier/booth/painpag/index.html