Dextromethorphan for phantom pain attenuation in cancer amputees: A double-blind crossover trial involving three patients

Background: Phantom limb pain is an intriguing pain syndrome that may result from damage to peripheral nerve tissue but could also involve central amplifying congeners. N-methyl-D-aspartate (NMDA)-receptor antagonists were recently shown to alleviate neuropathic pain in both animal and human models. Dextromethorphan is a noncompetitive NMDA-receptor antagonist. Study Design: Oral dextromethorphan (120-180 mg daily) was administered to three selected cancer patients during a 3-week study and an additional 1 month of treatment with the dosage subjectively judged to be best. Results: Oral dextromethorphan effectively reduced postamputation phantom limb pain, bestowing improvement in feeling and minimizing sedation in comparison with the pretreatment or placebo conditions, with no side effects. Pain recurred in one patient 1 month after treatment was stopped. Conclusions: Further clinical trials are warranted to determine the optimal dosage and identify which patients with phantom pain would benefit the most from this therapeutic approach.