chronic pain: real or imaginary or… malingering dr ian yellowlees consultant in pain management

Chronic Pain: Real or imaginary

Or…

Malingering

Dr Ian YellowleesConsultant in Pain Management

Aims

• Pain medicine: a specialty in its own right– (Why consult a pain Doc?)

• Pain mechanisms

• Pain assessment for treatment or medico-legal use

• (Treatment options)

1866 Back pain described as pathology..

“Railway spine”

20th Century mainstream.. Emphasis on diagnosis, pathology &

quick fixes..

Pull & Push

Surgery & pills failed…1953- first textbook of pain:

Pain is no longer considered exclusively either as a neurophysiological or a psychological phenomenon. Such a rigid dichotomy is obsolete, because pain is now recognised as the compound result of physiopsychological processes whose complexity is almost beyond comprehension.

The Management of Pain J Bonica Lea &

Febiger 1953

Psychologists become a core part of pain medicine

• Pain Mechanisms: a new theory. Melzack R Wall PD

Science 1965 50 971-979 – Gate control theory

“Pain is a complex perceptual process subject to modulation and manifesting a disconcertingly unreliable relationship to physical injury.”

The Biopsychosocial Model* -1977

• Widely accepted in many specialties – Google – 178,000 refs

• 1990’s Details are a core part of IASP post-graduate training in pain– Undergraduate medical, nursing, physiotherapy

curricula

* Engel GL: The need for a new medical model: a challenge for biomedicine. Science 1977 196 129-136

Physiological dysfunction +

neurophysiological changes

Illness behavior, Beliefs, Coping strategies, Emotions Distress

Culture, social interactions, Sick role

BIO

PSYCHO

SOCIAL

Pain medicine is a specialty…

• 2007 Faculty of Pain Medicine (RCA)

• Don’t expect other specialties to understand pain– Melzack & Wall: Textbook of Pain - 1280 pages

– Mercer’s Orthopaedic surgery, a standard postgraduate reference text - 6/1184 pages

– Bailey & Love’s Short Textbook of Surgery (‘worldwide sales > 800,000') - 2/1332 pages

What is pain?

• Definition

• Diagnosis

• Mechanisms

The Chronic pain patient

Definition

An unpleasant sensory and emotional experience... An unpleasant sensory and emotional experience...

...caused by actual or potential tissue injury,...caused by actual or potential tissue injury, ...or described in terms of such injury....or described in terms of such injury.

International Association for the Study of Pain

ICD10, DSM IV, (IASP)

• ICD10 classifies by causal agent, system, symptoms– Chronic pain by definition is pain persisting beyond time of

healing, therefore can’t use a classification based on physical causes

• DSM IV ‘pain disorder’– Diagnosis of exclusion

• IASP uses a classification based on description – Limited ability to encompass combination of sensory and

emotional factors

“Chronic pain syndrome”

• Often used by non specialist Dr– ‘dustbin diagnosis’ as a result of failure to identify a

physical cause for pain

• Often used to imply a psychological cause

• Not used by those working in the field

Diagnosis – if pushed!

Disorders

Degenerativeback pain

Worn outspine

Mechanicalback pain

Location

Leg pain

Toe pain

Sore balls

Aetiology

Crushed by abull pain

Post surgicalcock-up pain

Generalisedpain afteruse of bike

Psychology

Gross nasalobsession

You name ithe’s got itmad

No diagnosis in conventional sense. Describe in terms 4 components or biopsychosocial model

The 4 components of pain

• Sensory / Physical– Action in pain nerves (actually just sensory nerves)– NB: Activity in pain nerves ≠ pain

• Beliefs– Knowledge, expectations, fears, and attributions

• Behavioural– The effect of pain on behaviour, physical and emotional– coping strategies

• Emotions– The effect of the other three on mood and mood on the

other three

Assessment of pain problems

Investigations

• X ray / MRI findings– Changes seen on X-ray or MRI scan have no predictive

value for future pain or disability

– Reflected in current guidelines

• Blood tests– No value except to confirm inflammatory disease

(rheumatoid arthritis)

The absence of abnormal findings does not mean that there are no abnormal physical components, but simply that the tests used did not detect any

Physical measurement

• Measured as changes in performance– Performance relies on conscious drive to perform– Greatly influenced by psychological components

• NB: Treatment directed at the physical aspects of dysfunction only may not improve performance

So what is going on?

Physical: Soft tissue physiology and dysfunction

• Abnormal muscular function, & imbalance between muscle units, giving rise to localised stress concentrations– Starts within hours (POP)

• Changes in muscle metabolism and electrophysiology

• Increased fatigue and reduced endurance

• ‘Disuse syndrome’ or ‘deconditioning syndrome’ – May give rise to pain directly, or to increased

fatigue (TATT) and decreased function

• Altered patterns of movement and muscle function may also become learned responses and form a protective habit 

Nervous system changes

• Connections between nerves within the spinal cord & brain change in response to injury

– Interactions between different systems– Weather effects– Skin temperature changes

• The sensitivity of the cells also changes– Increasing sensitivity spreads to surrounding areas

• Changes can become permanent – Continue to cause pain long after the initial injury has apparently

healed

• This process is termed neuroplasticity– Eg CRPS

CRPS

Brain mapping

An aside - Reversing neuroplastic changes

• Mirror therapy – Phantom pains– Arthritis

• Hypnosis

• Cognitive behavioural therapy

• Drug treatments

Psychological: Fear avoidance

• Fear of pain & fear of damage– Limits activities – Limits treatment compliance– Becomes self perpetuating

• Less activity more deconditioning pain increasing disability

• Starts within few days of injury

Psychological: Catastrophising

I can’t work because of the pain, therefore:

I can’t earn any money

I can’t pay the mortgage

I will lose my house

My family will leave me

I have nothing to live for

There is no point in trying

Psychological: Control

• Influences reaction to illness and adversity

• Tolerance of lack of control is a product of genetics, learning & social conditioning

• Ability to gain a sense of control is fundamental to ability to cope

• Learned helplessness

Psychological: Depression

• Some symptoms in common with pain– “Diagnosis” difficult– Generally secondary to pain

• Waddell – Learned helplessness in the face of persistent pain

which the patient cannot control, and which impacts on the patient’s whole life

Psychological: Social interactions

• Pain occurs in a social context that may be helpful or destructive – Village collection

Presentation : “Illness behaviour” & “Functional

overlay”

• What people say and do that communicates to others that they are ‘ill’…… Related to: – Distress they feel

– Who they are communicating with • Important in MLA (Orthopaedic surgeons, neurologists..)

• May become part of the problem by further reducing performance and function

– May be connected with malingering

“Non-organic signs”“Waddell signs”

• Clinical signs that do not fit with anatomy or physiology

– Should prompt the examiner to look for the cause

– Do not simply assume malingering

PhysicalPsychological & behavioural

“Illness behaviour”

Illness behaviour Illness behaviour

Predictors of chronicity

• Age > 50, genetics

• Previous history of back pain

• Nerve root pain

• Pain intensity / disability

• Poor perception of general health

• Distress & depression

• Fear avoidance

• Catastrophising

• Pain behaviour (non-physical illness behaviour)

• Job dissatisfaction

• Duration of sickness absence

• Expectations about return to work

• Marital / family status– Single parent with young children, partner retired

or disabled

• Health status– Mental health, musculoskeletal conditions,

comorbidities

• Occupational / educational level

Malingering

• Malingering is a deliberate behaviour for a known external purpose.

• Not considered a form of mental illness or psychopathology – can occur in the context of other mental illnesses.

• Malingering can be expressed in several forms – pure malingering: falsifies all symptoms

• V rare. All the PI clients will have at least some activity in pain nerves

– partial malingering: has symptoms but exaggerates the impact upon daily functioning.

Assessment

• Try to explain the mechanisms underlying changes from pre accident to now– Physical– Psychosocial

• Take history into account– Were these changes going to happen anyway?– Predisposing factors (risk factors)

The essential ingredients

Review of history: ALL NOTES

Looking for physical, behavioural and psychological events

1985 1988 1989 1991 1993 1997 19991995

accident

Eg LBP events:

Objective assessment - questionnaires

• Many well validated questionnaires– Beck Depression inventory– Self efficacy– Sickness impact profile– Tampa scale of Kineasophobia

• Fear avoidance

• Pathological somatic focus

Decide if medical, physical and psychological assessments fit with questionnaires & history

– Coherent story hard to fake

The investigator’s video – what can it add?

What it tells us:She hung out the washing, once , for x minutes.

What it doesn’t tell us…

• Was the movement painful ?– would you expect it to be?

• How long can she do it?

• How often can she do it?– good days & bad– weather dependence?

• What happened afterwards?– pacing– pain killers

• Is she simply showing motivation to do as much as she can?

• Is this relevant to her employment?

However if the video captures this…

Evidence?

Extent of surveillance– 24/7 “big brother” style vs 20 minutes once in 4

years

Likely to add: • highly selected, edited single snapshot picture

– can not assess prior, concurrent, or post activity pain or function

– no context

• Should be predictable from good assessment

Assessment Timing

NB: legal processes may prevent effective treatment

• Single expert may be ok <6 months (?weeks)

• Multidisciplinary approach needed after this time

Conclusions

• Pain is a specialty• Physical changes are always present, but

often as physiological rather than pathological• Psychological changes are always present• Presentation is dependant on client and

assessor• Assessment requires multidisciplinary

investigation of the 4 components:– Cognitive– Sensory– Affective– Behavioral

“Pain is a complex perceptual process subject to modulation and manifesting a disconcertingly unreliable relationship to physical injury.”

Pain Mechanisms: a new theory. Melzack R Wall PD Science 1965 50 971-979

Dr Ian YellowleesIan.Yellowlees@painco.co.uk

www.painco.co.uk

Treatment

No need for us pain Docs..

If established chronic pain

• Full assessment – Make ‘non-diagnosis’

• Rarely any place for invasive techniques– subsequent nerve damage pain– dependence– need long term view– Window of opportunity injections

• Review of / optimise drugs– Neuropathic pain may need long term drugs– ordinary pain killers do not work– antidepressants, antiepileptics, ketamine, cannabinoids– ?? opiates

Requires a team approach

• Doctor

• Psychologist

• Physiotherapist

• Occ Therapist

• Nurse

• Pacing

• Goal setting

• Drug use

• Physical fitness

• Readiness for change

• Family issues

• Work issues

• Ergonomics

• Assertiveness

• Sleep

• “Pain management programme”– cognitive behavioural restructuring– philosophy of coping with rather than curing

problem• May need “windows of opportunity”• (NB recent link to brain physiology / anatomy)

– functional rehabilitation

• Occupational reassessment / training

This is not easy or quick..

Contemplation

Preparation

Act

ion

Maintenance

Relapse

Permanent exit Pre contemplation

cycles of change

Prochaska, J.O. & DiClemente, C.C. (1982) Pscychotherapy: theory, research and practice, 19: 276-288.

Note that relapse is not failure, simply part of the process

The big problems

For us…

• Nerve damage pain– shingles

– phantom limb

– post stroke

• Cancer pain– widespread

– 20% uncontrolled pain

• Back pain

For patients

• Accepting no cure

• Accepting no diagnosis

• Learning to change

• Maintaining change

Ian.yellowlees@painco.co.uk WWW.painco.co.uk