Chronic Pain

Andrew Skinner

South Tees Hospitals &

UHNT

IASP definition of pain

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

Definition

• Pain that outlasts the normal healing process

or

• 12 weeks!

How common is it?

• About 50% of the population – Back pain– Arthritis

• Fewer have severe pain – 15% of those with pain– Numerous papers of course

Elliott AM, Smith BH, Penny KI, Smith WC, Chambers WA. The epidemiology of

chronic pain in the community. Lancet 1999 Oct 9;354(9186):1248-52

But that is rather a lot

• JCUH pain clinic covers about 500000 people, so that makes:– 250000 with pain and – Perhaps 20000 with severe pain

What causes chronic pain?

• Chronic clear cut problems that won’t heal up by themselves– Arthritis

– Cancer

– Limb ischaemia

• Things that are out of proportion• Funny things you cannot explain• Injuries to the nervous system

– PHN

– Tic

– PSCP

What is the difference between acute and chronic pain?

Damage

Pain

Disability

Disease

Symptoms

Illness

Bio

Psycho

Social

What does this?

• Fear• Anxiety• Health beliefs (toe vs chest – angina)

• Anger• Guilt • Depression• Learned behaviour (kids)• Litigation• Secondary gain

Chronic clear cut problems that won’t heal up by themselves

• Easy – Diagnose– Treat– Cure– Pain killers!

Pain killers

• We all know what comes next…

Pain killers

Pain killers

• Do you trust someone who cannot tell a staircase from a ladder?

• Did you know it is only really intended as a teaching aid for cancer pain – the pain tends to worsen?

• Don’t forget acute pain gets better – more a snake than a ladder

Step one

• Non opioids– Paracetamol – basically – Aspirin?– The other NSAIDs?– Nefopam

• (and just what the hell is nefopam?)

Step one

• Paracetamol – basically– It is safe, cheap and pretty side effect free– Regular might be better than as needed– Seems to have an opioid sparing effect – Which means opioid side effects sparing

• I think aspirin is pretty good, but most people cannot take it long term

• BNF – “Nefopam may have a place in the relief of persistent pain unresponsive to other non-opioid analgesics. It causes little or no respiratory depression, but sympathomimetic and antimuscarinic side-effects may be troublesome.”

Step two

• Weak opioids and co-whatsamols– Codeine– Dihydrocodeine– Tramadol (or is this step two and a bit?)– Meptazinol (or is this step one and a bit?)– The NSAIDs? (opinion varies)

Step two

• Codeine and dihydrocodeine– Codeine is probably a prodrug

• Morphine or C-6-G• Which is important as only the former has been

studied in detail• But it doesn’t seem to suit everyone

– Dihydrocodeine• Opinion varies even more• But it might be stronger – addicts seem to know• And you can get it MR

Step two

• Tramadol suits some people

• Meptazinol is an indicator we were running out of ideas, but occasionally hits the spot

• Weak opioids seem to buy all the opioid side effects with fewer and lesser benefits

NSAIDs

• Non-steroidal anti-inflammatory drugs, usually abbreviated to NSAIDs, are drugs with analgesic, antipyretic and anti-inflammatory effects

• They are the least safe of all analgesics and a lot of people rarely prescribe them long term

NSAIDs

• GI bleeding and perforation– One of my long term patients died from this

• Renal failure

• Asthma

• CVS risks

• COX2?

NSAIDs

• Used to be said they were good for musculoskeletal pains not visceral

• But actually they just seem to be good pain killers

• And patient killers

• People argue about where on the WHO staircase they fit

Step three

• Strong opioids– Morphine – basically – Others

Step three

• There is little convincing evidence that anything is reliably better than morphine

• Some drugs suit some people, others other people

• But you cannot predict which by type of person or type of pain

Step three

• Not working?

• Underdosed?

• Adverse effects?

Step three

• Sedation

• Nausea

• Constipation

• Addiction or dependence • Itch• Hallucinations• Respiratory depression

• Are they over treated?

Step three

• Oxycodone

• Fentanyl

• Buprenorphine

• Hydromorphone• Pethidine• Diconal• Palfium

Step three

• Stick with one agent

• Get the dose up

• Treat the side effects

• Jolly them along

• Opioid switching isn’t magic– Or perhaps it is?

Step three

• Easy to decide for cancer pain

• Less easy for chronic non cancer pain

Step three

Step three – non cancer pain

• No injections• Speak to primary/secondary care• Previous addiction – caution not a ban• Medical practitioners only• Consent and contract• Single prescriber• Regular assessment – pain as the end point• We control the dose

– No breakthrough doses– No self escalation

TENs

• Transcutaneous Electrical Nerve Stimulator • Works for some chronic pains – about half• Harmless and cheap• Doctor free• Wears off• Good advice and persistence • Clearly ineffective for labour pains and acute

pain

Things that are out of proportion

• Bad back

• Bad neck

• Minor OA– You know what it is, but …

Things that are out of proportion“Disordered interoception”

• ? FM• ?? CF• ??? IBS• ??? Chronic migraine• ??? Chronic cystitis• ??? Side effects of drugs

I. M. Hunt, A. J. Silman, S. Benjamin, J. McBeth and G. J. Macfarlane The prevalence and associated features of chronic widespread pain in the community using the ‘Manchester’ definition of chronic widespread pain. Rheumatology 1999;38:275–279

Funny things

• Headache (except migraine)– Remember fear…– Remember MOH

• Facial pains (except Tic)– Remember diagnosis…

• Pelvic pains• Abdominal pains• Etc.• Etc.• You end up with symptomatic suggestions

unless you get lucky

Post surgical pain

• Is very common– Macrae W A. Chronic pain after surgery; Br J

Anaesth 2001; 87: 88–98

• And it is very difficult to treat

• And often omitted from consent (anger) and thought of as indicating a problem (fear)

• Recurrent pain after cancer surgery?

Neuropathic pain

• Neuropathic isn’t a synonym for difficult

• Plausible cause

• Right descriptors

• Right distribution

• Abnormal neurology

• Nothing wrong where it hurts

Neuropathic pain

• Idiopathic trigeminal neuralgia• PHN• Post amputation pains• Diabetic neuropathy • Multiple sclerosis• Pain following chemotherapy• HIV infection• Alcoholism• Cancer• Injury and surgery• Various other uncommon nerve disorders. • PSCP

Neuropathic pain

• Antidepressants– TCAs– SSRIs etc– Duloxetine

• Burning

• Nocturnal

• Sleep poor

Neuropathic pain

• Anticonvulsants

• Gabapentin

• Pregabalin?

• The rest

• The funny ones

Neuropathic pain

• Mexiletine• Ketamine• Opioids

– Oxycodone– Methadone

• NMDA antagonist

• Capsaicin• Cannabinoids • NOT TENS!

CRPS

• RSD

• Causalgia

• Disuse phenomenon in part

• OT & physio

• Neuropathic pain agents

• Blocks

So what do we do?

• Diagnosis– 8 OA hip– 6 vascular claudicants– Sarcoma of rib– Thalamic tumour– Ca breast– Myeloma– PMR

• And refer of course

So what do we do?

• Find out what the patient thinks and believes

• Is the patient’s cognition driving the illness?

• Are they depressed, anxious, angry etc?

• Can we treat this?

• Often psychologists are the first to really unearth patients beliefs

So what do we do?

• Reconcile them that the orthodox medical model has failed

• Look for under and over activity, cycling of activity

• Consider rehabilitation or PMP

So what do we do?

• Are there specific pain clinic treatments?

• Remember nerve blocking clinics…

• TENs?

• Medication

• Support

Une Lecon Clinique a la Salpetrie

Can we learn to shape illnesses towards recovery rather than towards chronicity?

Actually of course modern medicine does just the opposite

• Diagnostic puzzle• Ultra specialists• Repeated negative consultations• “Doctors despaired of me”• “No one can find what is wrong”• Iatrogenic injury

– Perhaps we’d be less dismissive if we remembered it was often our fault, not the patients

Back pain - the clinical dilemma

Back pain can be a symptom of serious spinal disease

BUT

Most back pain is due to backache, not disease

How the health care system contributes to chronic pain

• inconsistent advice

• lack of clear, understandable information

• reluctance to abandon a curative model

Some common beliefs about chronic pain :

- that it is due to serious disease, which has been overlooked- that it is due to serious,irreversible damage- that it means being vulnerable to further injury- that it will inevitably lead to increasing disability / dependency- that health staff do not believe they are in pain

Underlying belief

Hurt = harm

• understandable

• true for acute conditions

• basis of the medical model

Consequences of pain beliefs :• increased distress -

anxiety, anger, depression

• changes in behaviour - increased consulting, seeking referrals or investigations, ‘ill’ behaviour - bedrest

• poorer outcome - more likely to drop out from rehabilitation, less likely to return to work

Fear avoidance model Fear of pain (hurt, harm or both) Avoidance - of whatever makes it worse

*Survival value - evolutionary advantage *Acute conditions - limits damage, reduces nociception But *Chronic conditions - barrier to rehabilitation (Lethem et al 1983)

Expectation of pain

- avoidance- no increase in pain- avoidance reinforced

eg Belief that muscle pain = damage - expect pain with activity - reluctant to exercise - avoid mobilisation - drop out of rehabilitation (Feuerstein 1991)

Fear of pain

Confrontation Avoidance

Desire to return to Avoidance of physical /natural activities social activitiesMobilise, exercise Loss of spinal mobilityAccurate interpretation Misinterpretation ofof pain pain Effective rehabilitation Increased disability

(Lethem et al 1983)

Assessment of fear avoidance beliefs

• Back Beliefs Questionnaire (Symonds et al 1996)

• Fear Avoidance Beliefs Questionnaire (Waddell et al 1993)

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