Morning Report

Steven Hart

HPI 45 year old female presents to clinic to

establish new PMD CC: left leg pain Recent medical history

Pain in left LE for 1 mo with several visits to ER left femoral thrombus and emboli to left lower

extremity eventually diagnosed Left AKA required Now (6 weeks later) c/o persistent pain where

lower left leg was and sensations in left leg. Started on coumadin prior to discharge

Physical exam C/w left AKA

Incisions clean and healing well Non-tender, no erythema, skin intact

Exam otherwise unremarkable

Topics Phantom Limb Pain (PLP)

Definitions Epidemiology Etiology / Pathophysiology Evaluation / Differential Treatment

Prevention / Short term Long term

Definitions Stump pain

Pain in the residual portion of the limb

Phantom Limb Pain (PLP) A painful sensation perceived in a missing limb

after amputation

Phantom Limb Sensation (PLS) Any sensation of the missing limb (paresthesia,

dysesthesia, hyperpathia) except pain.

Epidemiology Phantom Limb Sensation (PLS)

Occurs in 85% - 98% of amputees within 3 weeks of amputation

8% may occur after 1-12 months Usually resolves after 2 – 3 years

spontaneously if PLP does not develop Location affects intensity and likelihood of

PLS Proximal ie. Above the knees or elbows Dominant extremity

Phantom Limb Pain (PLP) 60-70% of amputes experience PLP Location again an important factor

Proximal 68-88% hemipelvectomy 40-88% hip disarticulation 51% upper limb 20% AKA 0-2% BKA

Epidemiology

Epidemiology Phantom Limb Pain (PLP) – continued

Time Occurs 1 week to decades after amputation Pain onset after one year in < 10% May diminish and eventually resolve with time More likely, however, it will persist chronically

Pain in limb prior to amputation increases risk for PLP

Pains in other parts of the body Headache Joint pain Sore throat Abd pain Back pain

Epidemiology Stump Pain

Occurs in about 50% of amputees Frequently associated with phantom

pain

Etiology Neuromas

Dominate theory until last 10-15 years Irritation of the severed nerve endings Inflammation resulted in anomalous signals

to the brain perceived as pain. Treatments included removal of nerve

endings or further amputation. Only resulted in temporary improvement Eventually pain returned, frequently worse

Modern thought - One of many factors causing PLP

Etiology Neuroma – their role

mechanical/neurostimulation spontaneous and abnormal evoked activity in sodium channel production in sensitivity of neuromas to norepinephrine Thus, pain with stress or other emotional states A similar phenomenon occurs in the cell body of

the dorsal root ganglia just upstream

Etiology -spinal cord level

signal from neuromas and doral root ganglia cell bodies

activity of neurons in dorsal horns

upregulation of several genes- especially receptive genes- in N-methyl-D-aspartate

(NDMA)

Etiology -spinal cord level

Anatomical reorganization (rewiring) Perph nerve transection

degeneration of afferent C-fiber terminals in Lamina II

These may replaced by A mechanoreceptive afferents

Results in pain evoked by simple touch

Etiology - Central mechanism

Somatosensory cortex remapping PLS/PLP evoked by

touching face in a hand amputee

Verified by multiple neuroimaging studies in humans

Etiology - Central mechanism

Plastic changes occur in the Thalamus Stimulation of thalamus in amputees

causes PLP and PLS Similar stimulation does not cause

any pain in non-amputees

Differential Diagnosis of PLP Radicular pain

Disk herniation Angina Post herpetic neuralgia Metastatic cancer Infection / poor wound healing

Treatment of PLP -Overview

Poorly studied field placebo effect common Spontaneous resolution does happen

Fewer than 10% of PLP patients receive lasting relief

Frequently, neuropathic treatment recommended, but few studies to support this Most neuropathic treatment trials do not include

PLP Prevention of PLP is a new area of interest

Treatment of PLP -Overview

Multiple approaches Prevention Medical Physical Therapy Nerve Blocks Nerve stimulation

Transcutaneous, spinal cord, deep brain, motor ECT Psychological Therapy

Treatment of PLP -Prevention

Goal – avoid/control the changes that lead to chronic pain

Prevent or control pre, peri and post-operative pain Use of pre, intra and post-op epidural

blocks has been shown to reduce occurrence of PLP at 12 mo post-op

Mixed results in follow up studies

Calcitonin infusions Ketamine Transcutaneous electrical

stimulation

Treatment of PLP -Prevention

Treatment of PLP -Medical Management

Anti-depressants Tricyclic anti-depressants Anti-convulsants NMDA receptor antagonists Opiates Beta Blockers Misc

Treatment of PLP -Medical Management

Tricyclic anti-depressants Frequently used Well studied in other neuropathic pain

syndromes Diabetes, post herpetic neuralgia

Poorly studied in PLP One randomized study showed no

effect, other studies showed some benefit

Treatment of PLP -Medical Management

Anti-convulsants Carbamazepine

Effective for intense, brief, lancinating type of pain

Gabapentin Effective in one small randomized trial

Topiramate Small randomized study supported it

effectiveness

Opiates Effective for both stump pain and PLP May affect cortical reorganization Considered the mainstay of treatment Tolerance/Addiction

Most amputees have a short life expectancy because of underlying disease.

Balance quality of life vs risk of opiate addiction/dependence

Treatment of PLP -Medical Management

NMDA receptor antagonists Ketamine – effective, must be IV Memantine – oral, ineffective Dextromethorphan

Small randomized studies have supported its use.

Improved feeling No, small sedation No increased side effects from placebo

Treatment of PLP -Medical Management

Treatment of PLP -Physical Therapy

Sensory discrimination training Designed to alter the cortical map Shown to significantly reduce PLP and

cortical reorganization

Transcutaneous electrical nerve stimulation

Spinal Cord Stimulation Deep brain stimulation Motor cortex stimulation

All very preliminary

Treatment of PLP -Neurostimulation

Treatment of PLP Acupuncture

May provide short term relief ECT

Several case reports of pain resolution after treatment

Psychological Therapy Relaxation training hypnosis

Conclusion PLP is common in amputees The cause is complicated and involves

virtually all levels of the nervous system Prevention of chronic pain may be

possible but further investigation is needed

Chronic pain management is difficult and should be multifaceted

There is little evidence to guide therapy at this time.