Pain Management for Amputees

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

2. 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

3. 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

4. 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)

5. 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

6. 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)

7. 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)

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

9. 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

10. 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

11. 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

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

13. 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

14. 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

15. Non-Medical Treatments • TENS • Vibration Therapy • Acupuncture • Hypnosis • Biofeedback • Electroconvulsive Therapy • Mirror Treatment • Cognitive Behavioural Therapy • Farabloc (Conine 1993)

16. 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

17. 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

18. 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 post-op period (Pinzer, 1996)(Fisher, 1991)

19. 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)

20. Other TCA’s • Nortryptiline • Imipramine • Doxepin

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

22. 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

23. 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

24. 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 pain

25. 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

26. 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

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

28. 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):S25-30 • Malis et al, Cochrane database of Systemmatic Reviews, 2003(2):CD002918 • 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, 8th World Congress on Pain, 1996 pg376