Phantom limb pain may appear in up to 85% of patients after
amputation. There is no effective treatment. Perioperative epidural infusion of
morphine and
bupivacaine, alone or in combination, is effective in preventing
phantom limb pain in patients with pre-existing limb
pain. Serious side-effects, however, make them difficult to manage on a general ward.
Clonidine has been shown to be an effective postoperative
analgesia when applied epidurally. To mitigate the potentially serious side-effects of all these drugs, we have studied their combined efficiency in preventing
phantom limb pain in a prospective controlled study of 24 patients undergoing lower limb
amputation. In the study group (n = 13), an epidural infusion containing
bupivacaine 75 mg,
clonidine 150 micrograms and
diamorphine 5 mg in 60 ml
normal saline was given at 1-4 ml/h 24-48 h preoperatively and maintained for at least 3 days postoperatively. The control group (n = 11) received on-demand
opioid analgesia.
Pain was assessed by visual analogue scale at 7 days, 6 months and 1 year. At 1 year follow-up, one patient in the study group and eight patients in the control group had
phantom pain (P < 0.002) and two patients in the study group versus eight patients in the control group had
phantom limb sensation (P < 0.05). There was no significant improvement in stump
pain. We conclude that perioperative epidural infusion of
diamorphine,
clonidine and
bupivacaine is safe and effective in reducing the incidence of
phantom pain after
amputation.