Pathophysiological mechanisms of neuropathic pain

Neuropathic pain is a common problem in clinical practice and one that adversely affects patients’ quality of life. Converging evidence from animal and human studies demonstrates that neuropathic pain arises from a lesion in the somatosensory system. Injured peripheral nerve fibers give rise to an intense and prolonged ectopic input to the CNS and, in some cases, also to secondary changes in dorsal horn neuronal excitability. Convincing evidence now suggests that classifying neuropathic pain according to a mechanism-based rather than an etiology-based approach might help in targeting therapy to the individual patient and would be useful in testing new drugs. This article summarizes our current understanding of the peripheral and central pathophysiological mechanisms underlying neuropathic pain and focuses on how symptoms translate into mechanisms.