ABSTRACT
Human survival necessitates pain sensation. It protects us from imminent danger by triggering reflexes and aversive responses. If tissue has been damaged, a series of adaptive changes occurs rapidly in the sensory system in and around the injury. Such ‘normal’ pain pathways are well understood in terms of the receptor types, neuroanatomy, and neurochemicals involved in transmitting and carefully modulating this information. Paroxysmal and chronic persistent, maladaptive pains and paresthesias resulting from nerve or spinal cord injury or inflammation are also common but are poorly understood. These sensations follow distinctly separate anatomical pathways or subtend short circuits, adopt a different neurochemical repertoire, and are poorly modulated; they are thus dubbed neuropathic pain. These maladaptive pain syndromes seem to be the price we pay for damage to our otherwise exquisite sensory pathways.
