IMPLICATIONS: NMDA receptors play a substantial role in central nervous system changes underlying neuropathic pain. In a placebo-controlled double-blinded study we tested the effect of 30 mg memantine on chronic phantom limb pain and pain-associated cortical reorganization.

During recent years, new insights into the mechanisms underlying induction and maintenance of chronic pain states have been gained through studies in animals and humans with peripheral nerve lesions. In neuropathic pain conditions, neuroplasticity in the central nervous system (CNS) seems to play a crucial role (1, 2). Among different subsets of neuropathic pain, phantom limb pain (PLP) is the most illustrative example for the contribution of the CNS to chronic pain disorders. As PLP is felt in a part of the body that is absent, it is probable that other sites than the periphery might be the generating source of pain.