Pain Management for Amputees

Dr Craig DavenportRehabilitation Registrar

Liverpool Hospital19th August 2005

Pain in the AmputeePre-operative pain – ischaemic, infection, traumaEarly Post-op pain – somatic vs neuropathic, stump vs phantom limbLate post-op pain – stump vs phantom limb

Stump PainSomatic stump pain usually resolves as the wound healsCan trigger Phantom painProlonged stump pain usually attributable to local pathology – delayed wound healing, infection, surgical complications, poor prosthetic fit, neuromas, adherent scarsLate onset stump pain - neuromas, prosthetic fit, claudication, bony overgrowth, osteoarthritis , tumour recurrence

Phantom Pain vs SensationPhantom limb Sensation – almost universal

doesn’t correlate with pain reports

Non-painful phantom sensations of 3 types:Kinetic senstations (movement)Kinesthetic (size,shape,position)Exteroceptive (touch, pressure, temperature, itch, vibration)

Phantom Limb PainPhantom pains often described as crushing, toes twisting, hot iron, burning, tingling, cramping, shocking, shooting, “pins & needles”

Tends to localise to more distal phantom structures (eg fingers and toes)

prevalence in early stages 60-80%

Independent of age in adults, gender, level or side of amputation

PLP OnsetMostly onset immediately after amputation, some at two weeks. Rarely months later1/3 maximal immediately post-op and generally resolved by 100 days½ slowly peaked then improved within 100 days¼ slower rise toward maximal pain (Weinstein, 1996)

PLP Natural HistoryTends to diminish in severity and frequency over time, with resolution over several weeks to 2 yearsOne study – 72% at 8 days, 65% at 6 months, 59% at 2 years (Jensen, 1985)

Duration of episodes vary - continuous 12%, days 2%, hours 37%, seconds 38% (Sherman & Sherman,1983)

50% had decreasing PLP with time50% no change or increase over time (Sherman et al, 1984)

PLP Natural HistoryStump pain intensity tends not to correlate with PLP intensity

2/3 experience telescoping of phantom limb

Also in KidsPLP also occurs in children, often under-recognised

70-75% at 7 years after amputation, but none severe (Boyle et al, 1982)

Less in congenital limb deficiency

Why does pain occur?Peripheral neuropathic mechanisms:

immediate nerve injury dischargelocal nociceptive substancesdeafferentationectopic firingneuromasEphatic transmission b/w sensory and sympathetic fibers

Why does pain occur?Spinal cord:

Expansion of receptive fieldsLow-threshold inputs when high-threshold inputs lostDisinhibition

Brain:

Cortical engram generates pain in absence of stimuliCortical reorganisation

Why does pain occur?Non-neurological factors:

Skin blood flowStump temperatureMuscle tension

Psychological factors:

Stressors/ depression/ anxietyNot personality types

Treatment ApproachNon-Medical and Medical/SurgicalPrevent contracturesLimit oedemaAdequate Post-op AnalgesiaDesensitisation - massage/bandagingGet patient moving, distraction helpsEarly prosthetic training

Treatment ApproachSomatic Pain – non-pharm, simple analgesics, NSAIDs, tramadol, opioids

Neuropathic/Phantom Limb Pain – follow neuropathic pain principles – Non-pharm, TCA’s, anticonvulsants, local anaesthetics

Non-Medical TreatmentsTENSVibration TherapyAcupunctureHypnosisBiofeedbackElectroconvulsive TherapyMirror TreatmentCognitive Behavioural TherapyFarabloc (Conine 1993)

Peripheral StimulationControlled trial of TENS/sham/largactil showed benefit at 16 weeks; no difference beyond 12 months, improved stump healing (Finsen,1988)

Auricular TENS – controlled trial showed beneficial (Katz, 1991)

Vibration & Acupuncture only case reports

Potential Drug TreatmentsEpidural anaesthesiaAmitriptyline (Tricyclic antidepressants)Anticonvulsants – carbamazepine, gabapentinClonazepamOpioids/TramadolMexiletine/lignocaineBeta/alpha blockers - clonidineIntrathecal opioids/ lignocaineCapsaicin cream, NSAID creamIV KetamineSympathetic ganglion block

Pre-emptive AnalgesiaPre-operative anaesthesia:Early trials looked promising but less robustBetter designed trials did not show benefit in PLP (Nikolajsen 1997)

Peri-op regional nerve blocks – decreased use of opioids in early post-op period (Pinzer, 1996)(Fisher, 1991)

Amitriptyline (Endep)Well documented for neuropathic pain (Kingery, 1997)

Generally considered effective

Dose 10mg up to 150mg (75mg in elderly)

Recent RCT in PLP no benefit (Robinson 2004)

Other TCA’sNortryptilineImipramineDoxepin

Gabapentin (Neurontin)Evidence in neuropathic painRCT in PLP benefit at 6 weeks (Bone 2002)

100mg tds up to 1200mg tdsRelatively well toleratedMain side effects are dizziness/somnolence/memory impairmentNot subsidised by PBS for pain $150/mth

Other AnticonvulsantsCarbamazepine (Tegretol) – cheap; proven in neuropathic pain, nasty haematological S/E’s

Lamotrigine (Lamictal)– emerging evidence for neuropathic pain

Valproate (Epilim)– lacks evidence, not very effective

OthersCapsaicin – no RCT for PLP; unpleasantIV calcitonin (post-op) – unknown mechanism; reduced early PLP, longer term effect lacks evidence (Jaeger, 1992)

Mexiletine – open label study in PLP; risk of sudden deathBeta-blockers – limited reportsBenzodiazepines – clonazepam limited reportsIV Ketamine – reduces ‘wind-up’ – short-term reduction in PLP (Nikolajsen 1996)

Opioids – probably have a roleTramadol – alternative to opioidsNSAIDs not effective

Pain and ProsthesesUse of Prosthesis – may increase or decrease painPoor prosthetic fit may irritate stump tissues or neuroma revise socketMusculoskeletal pain due to altered biomechanics PTK/thigh lacerSensitive stump may require altered prosthetic prescription Silicon liner, Thigh LacerStump bandaging/ hard casting may reduce pain

Neuromas localized pain, sharp/shooting/paraesthesiaReproduced by local palpation, relieved by LA injectionTinel’s signTry socket relief and local steroid/LA injectionAblation – Phenol alcohol injection into neuromaSurgery – not much evidence, high recurrence rate

Nasty InterventionsStump surgery – for defined pathology bury nerve terminal in bone, excise bony spursDREZ lesioningSympathectomy – conclusive evidence lacking (Mailis 2003)

Spinal cord stimulation – works but expensive, infection riskDeep Brain or Motor Cortex Stimulation – works but effect decreases with timeCordotomy/thalamotomy

PrognosisWhen PLP persists 6 months, prognosis for spontaneous improvement is poor

Probably <10% have persistent severe pain

ReferencesBone et al, Reg Anaesth & Pain Med, 2002;27(5):481-6Boyle et al, Oncology, 1982;10:301-312Conine et al, Can J Rehab, 1993;6:155-61Finsen et al, J of Bone & Joint Surg Br,1988;70:109-12Fisher et al, Anaesth Analg, 1991;72:300-3Halbert et al, Clin Journal of Pain, 2002; 18:84-92Jaeger et al, Pain , 1992;48:21-7Jensen et al, Pain, 1985;21:267-78Katz et al, J of Pain & Symp Man, 1991; 6:73-83Kingery, Pain, 1997;73(2):123-39Levy et al, APMR, 2001; 82(Suppl 1):S25-30Malis et al, Cochrane database of Systemmatic Reviews, 2003(2):CD002918Nikolajsen et al, Pain, 1996;67:69-77Nikolajsen et al, Lancet,1997;350:1353-7Pinzur et al, J Bone % Joint Surg Am, 1996;79:1752-3Robinson et al, APMR,2004;85:1-6Sherman et al, Pain,1984;18:83-95Sherman & Sherman, Am J of Phys Med, 1983;62:227-38Weinstein, 8th World Congress on Pain, 1996 pg376