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 Effectiveness ~ Ibuprofen Bradley N. Eng. J. Med 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 Eisenberg J. Clin. Onco. 1994

Symptom control NSAID Annual GI bleed risk: % / year Annual death rate: % / 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 k Usually deep seated Anatomically diffuse l Visceral functions.

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 PreopPost-opp-value CABG (51) <0.001 SCS (53) <0.001 Mannheimer et al Circulation 1998

Symptom control 6-months cardiac mortality and morbidity MortalityMorbidityStroke CABG (51)778 SCS (53)172 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 Pain Depression Think negative In-activity Medical Dependence Insomnia Socially deprived

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)

Pain as a disease Cognitive behavioral therapy Depression (HADS)

Pain as a disease Cognitive behavioral therapy Catastrophising (PCS)

Pain as a disease Cognitive behavioral therapy 40 meter carrying load (pounds)

Pain as a disease Cognitive behavioral therapy Analgesic consumption (types)

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 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) AHNHPWH QEHUCH QMHPYNEH Smaller scale ones at DK, PM, etc.

Resources for you Internation Association for the Study of Pain HK College of Anaesthesiologists Oxford pain Internet site