Oral ketamine therapy in the treatment of postamputation stump pain

Background: Hyperactivity of N-methyl-D-aspartate (NMDA) receptors may be one of the factors in the maintenance of post-amputation stump pain. Case report: Ketamine - a clinical available NMDA receptor antagonist - was administered intravenously to a patient with established stump pain in a double-blind saline-controlled fashion. Following infusion stump pain was alleviated for 31 hours. Ketamine reduced the allodynic area and wind-up-like pain and increased pressure-pain thresholds. Treatment was started with ketamine 50 mg x 4 per day dissolved in juice. No side effects or development of tolerance were observed during a 3-month treatment period. Conclusion: NMDA receptor antagonists may have a potential in the treatment of neuropathic pain, including stump pain.