RESUMEN
Frequent simulation and irritation of NMDA receptors by glutamate mediators can lead to burning pain, allodynia and hyperalgesia, even after stopping the irritant factor. Opioid-induced hyperalgesia and peripheral nerve injuries in lower extremities orthopedic surgeries can also make the same symptoms, which sometimes make it difficult to diagnose it from causalgia [type II complex regional pain syndrome]. Post-traumatic neuralgia is not so common, often does not respond well to usual medications and prolongs the patient's stay in hospital. Noting the anatomical and physiological aspects of pain transmission pathways and also role of pain transmission inhibitors via NMDA receptors in pain management, opens us a new window to the role of medicines such as ketamine in prevention and treatment of neuropathic or chronic postoperative pains. We report a case involving refractory neuropathic pain which is eventually controlled with low dose of ketamine