18.5 Phantom Limb Pain Flashcards
You are called to see a 25-year-old man who suffered a traumatic below knee amputation 24 hours ago.
He is using patient controlled analgesia (PCA) with intravenous morphine and was comfortable until two
hours ago, when he started to experience severe pain.
a) Why might his pain control have become inadequate? (5 marks)
> > Failure of morphine delivery:
check syringe full,
pump working well,
patient using pump well,
cannula patent.
> > Acute pain:
failure to manage acute pain due to e.g.
development of infection,
wound dehiscence,
haematoma formation in stump.
> > Neuropathic pain:
development of phantom limb pain.
Phantom limb pain occurs as a result of nerve damage, resulting in changes to the nervous
system at multiple locations,
causing dysfunctional transmission of
sensory information and abnormal pain perception.
> > Other pain source: major trauma victim – check for coexisting injuries.
b) How would you re-establish optimal pain control? (6 marks)
.» Assessment of pain,
degree of psychological distress
and physiological effect.
> > Intravenous morphine titrated to effect,
oxygen saturations,
respiratory rate,
heart rate
and blood pressure monitoring.
> > Increase PCA bolus dose
and hourly limit if considered safe to do so.
> > Multimodal approach:
ensure regular paracetamol and NSAIDs, if
appropriate. Consider gabapentinoid.
> > Consideration of addition of ketamine ivi ***
(up to 15 mg/h) if difficulty
re-establishing control.
> > Consideration of sciatic and
femoral nerve blocks or even epidural if pain
very severe and intractable.
c) Which factors would suggest that this patient has phantom limb pain (PLP)? (3 marks)
> > Nature of pain:
shooting, burning, cramping, aching.
> > Location of pain:
distal to stump, associated with the missing leg.
> > Degree of pain:
apparent disproportion between pain experienced and
stimulus applied.
d) What further pharmacological options are available for managing PLP? (6 marks)
**
> > Amitryptilline is first-line treatment, *
moving on to any of the other three if
ineffective/not tolerated.
> > Duloxetine.*
> > Gabapentin.
> > Pregabalin.
> > Capsaicin cream if oral treatment not tolerated.
> > (Tramadol use restricted to acute rescue therapy).
