[Stump pain relieved by continuous intravenous ketamine infusion therapy]

We experienced a case of stump pain relieved by continuous intravenous ketamine infusion therapy. A 59-year-old male had his left first through fourth toes amputated because a giant iron plate at work fell on his left foot fifteen years ago. Thereafter he had refractory spontaneous burning pain and night pain on his stump. On examination, we found his left foot skin hard, lustrous, and with sweating disturbance, allodynia and hyperpathia. As intravenous administrations of ketamine 10 mg and thiamylal 50 mg were positive as a drug challenge test, we performed intravenous ketamine infusion at 1 mg.kg-1.hr-1 for 1 hour and a half. After this treatment, his visual analogue scale (VAS) improved dramatically to 0 mm, and night pain, allodynia and hyperpathia disappeared for three days. Thereafter stump pain was relieved to the level of VAS 20 mm. Therefore we diagnosed his stump pain as central pain of neuropathic origin. We suspect that continuous intravenous infusion of ketamine, a noncompetitive blocker of N-methyl-D-aspartic acid receptor, might be an effective and useful alternative treatment in a patient with refractory stump pain.