Treatment of Neuropathic Pain

Neuropathic pain is generated by disruption of normal nerve connections and/or abnormal hyperactivity at some level of the pain sensory system. Neuropathic pain syndromes due to peripheral nervous system injury are commonly encountered in clinical practice and often adversely affect patients ’ quality of life. Pharmacotherapy is the mainstay of neuropathic pain management, with the majority of clinical data sup-porting the use of three main drug classes: (1) tricyclic antidepressants: (2) anticonvulsants: and (3) anesthetic-antiarrhythmics. Clonidine, opioids, capsaicin, nonsteroidal anti-inflammatory drugs, immu-nosuppressants, and the novel antidepressants may also have a role in some patient populations. A N GENERATED BY disruption of normal P nerve connections and/or abnormal hyper-activity at some level of the pain sensory sys-tem is termed neuropathic. Such abnormal and persistent pain may result from neural injury at any point within the central or peripheral nerv-ous system. This review will focus on the causes and treatment of neuropathic pain of pe-ripheral origin. Several possible mechanisms by which nerve dysfunction can cause pain have been proposed. No one mechanism is disease spe-cific, and each disorder may involve one or more mechanisms simultaneously. Current evidence suggests that peripheral neuropathic pain is sustained by one or more of the follow-ing factors: hyperactivity in primary afferent or central nervous system nociceptive neu-rons; loss of central inhibitory connections; and increased activity in sympathetic effer-ents. ’ Therefore, regardless of the location and etiology of injury in the peripheral nervous system, pain may be generated and maintained centrally, peripherally, or both.2 It remains un