Pain Management for Amputees Dr Craig Davenport Rehabilitation

Pain Management for Amputees Dr Craig Davenport Rehabilitation Registrar Liverpool Hospital 19 th August 2005

Pain in the Amputee Pre-operative pain – ischaemic, infection, trauma Early Post-op pain – somatic vs neuropathic, stump vs phantom limb Late post-op pain – stump vs phantom limb

Stump Pain Somatic stump pain usually resolves as the wound heals Can trigger Phantom pain Prolonged stump pain usually attributable to local pathology – delayed wound healing, infection, surgical complications, poor prosthetic fit, neuromas, adherent scars Late onset stump pain - neuromas, prosthetic fit, claudication, bony overgrowth, osteoarthritis , tumour recurrence

Phantom Pain vs Sensation Phantom 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 Pain Phantom 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 Onset Mostly onset immediately after amputation, some at two weeks. Rarely months later 1/3 maximal immediately post-op and generally resolved by 100 days ½ slowly peaked then improved within 100 days ¼ slower rise toward maximal pain (Weinstein, 1996)

PLP Natural History Tends to diminish in severity and frequency over time, with resolution over several weeks to 2 years One 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 time 50% no change or increase over time (Sherman et al, 1984)

PLP Natural History Stump pain intensity tends not to correlate with PLP intensity 2/3 experience telescoping of phantom limb

Also in Kids PLP 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 discharge local nociceptive substances deafferentation ectopic firing neuromas Ephatic transmission b/w sensory and sympathetic fibers

Why does pain occur? Spinal cord: Expansion of receptive fields Low-threshold inputs when high-threshold inputs lost Disinhibition Brain: Cortical engram generates pain in absence of stimuli Cortical reorganisation

Why does pain occur? Non-neurological factors: Skin blood flow Stump temperature Muscle tension Psychological factors: Stressors/ depression/ anxiety Not personality types

Treatment Approach Non-Medical and Medical/Surgical Prevent contractures Limit oedema Adequate Post-op Analgesia Desensitisation - massage/bandaging Get patient moving, distraction helps Early prosthetic training

Treatment Approach Somatic 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 Treatments TENS Vibration Therapy Acupuncture Hypnosis Biofeedback Electroconvulsive Therapy Mirror Treatment Cognitive Behavioural Therapy Farabloc (Conine 1993)

Peripheral Stimulation Controlled 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 Treatments Epidural anaesthesia Amitriptyline (Tricyclic antidepressants) Anticonvulsants – carbamazepine, gabapentin Clonazepam Opioids/Tramadol Mexiletine/lignocaine Beta/alpha blockers - clonidine Intrathecal opioids/ lignocaine Capsaicin cream, NSAID cream IV Ketamine Sympathetic ganglion block

Pre-emptive Analgesia Pre-operative anaesthesia: Early trials looked promising but less robust Better designed trials did not show benefit in PLP (Nikolajsen 1997) Peri-op regional nerve blocks – decreased use of opioids in early postop period (Pinzer, 1996)(Fisher, 1991)

Amitriptyline (Endep) Well documented for neuropathic pain (Kingery, 1997) Generally considered effective Dose 10 mg up to 150 mg (75 mg in elderly) Recent RCT in PLP no benefit (Robinson

Other TCA’s Nortryptiline Imipramine Doxepin

Gabapentin (Neurontin) Evidence in neuropathic pain RCT in PLP benefit at 6 weeks (Bone 2002) 100 mg tds up to 1200 mg tds Relatively well tolerated Main side effects are dizziness/somnolence/memory impairment Not subsidised by PBS for pain $150/mth

Other Anticonvulsants Carbamazepine (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

Others Capsaicin – no RCT for PLP; unpleasant IV calcitonin (post-op) – unknown mechanism; reduced early PLP, longer term effect lacks evidence (Jaeger, 1992) Mexiletine – open label study in PLP; risk of sudden death Beta-blockers – limited reports Benzodiazepines – clonazepam limited reports IV Ketamine – reduces ‘wind-up’ – short-term reduction in PLP (Nikolajsen 1996) Opioids – probably have a role Tramadol – alternative to opioids NSAIDs not effective

Pain and Prostheses Use of Prosthesis – may increase or decrease pain Poor prosthetic fit may irritate stump tissues or neuroma revise socket Musculoskeletal pain due to altered biomechanics PTK/thigh lacer Sensitive stump may require altered prosthetic prescription Silicon liner, Thigh Lacer Stump bandaging/ hard casting may reduce

Neuromas localized pain, sharp/shooting/paraesthesia Reproduced by local palpation, relieved by LA injection Tinel’s sign Try socket relief and local steroid/LA injection Ablation – Phenol alcohol injection into neuroma Surgery – not much evidence, high recurrence rate

Nasty Interventions Stump surgery – for defined pathology bury nerve terminal in bone, excise bony spurs DREZ lesioning Sympathectomy – conclusive evidence lacking (Mailis 2003) Spinal cord stimulation – works but expensive, infection risk Deep Brain or Motor Cortex Stimulation – works but effect decreases with time Cordotomy/thalamotomy

Prognosis When PLP persists 6 months, prognosis for spontaneous improvement is poor Probably <10% have persistent severe pain

References Bone et al, Reg Anaesth & Pain Med, 2002; 27(5): 481 -6 Boyle et al, Oncology, 1982; 10: 301 -312 Conine et al, Can J Rehab, 1993; 6: 155 -61 Finsen et al, J of Bone & Joint Surg Br, 1988; 70: 109 -12 Fisher et al, Anaesth Analg, 1991; 72: 300 -3 Halbert et al, Clin Journal of Pain, 2002; 18: 84 -92 Jaeger et al, Pain , 1992; 48: 21 -7 Jensen et al, Pain, 1985; 21: 267 -78 Katz et al, J of Pain & Symp Man, 1991; 6: 73 -83 Kingery, Pain, 1997; 73(2): 123 -39 Levy et al, APMR, 2001; 82(Suppl 1): S 25 -30 Malis et al, Cochrane database of Systemmatic Reviews, 2003(2): CD 002918 Nikolajsen et al, Pain, 1996; 67: 69 -77 Nikolajsen et al, Lancet, 1997; 350: 1353 -7 Pinzur et al, J Bone % Joint Surg Am, 1996; 79: 1752 -3 Robinson et al, APMR, 2004; 85: 1 -6 Sherman et al, Pain, 1984; 18: 83 -95 Sherman & Sherman, Am J of Phys Med, 1983; 62: 227 -38 Weinstein, 8 th World Congress on Pain, 1996 pg 376