Neuropathic pain is a complex, chronic pain state that usually is accompanied by tissue injury. With Neuropathic pain", the nerve fibers themselves may be damaged, dysfunctional or injured. These damaged nerve fibers send incorrect signals to other pain centers. The impact of nerve fiber injury includes a change in nerve function both at the site of injury and areas around the injury. One example of Neuropathic pain" is called phantom limb syndrome. This occurs when an arm or a leg has been removed because of illness or injury, but the brain still gets pain messages from the nerves that originally carried impulses from the missing limb. These nerves now misfire and cause pain.

Numerous mechanisms have been postulated as substrates for NP; in any given patient, multiple mechanisms may coexist, including excitotoxicity, abnormal expression of sodium channels, ectopic discharge, deafferentation, or central sensitization. These underlying mechanisms are increasingly important considerations when selecting therapy.

Neuropathic pain" can be divided into 3 broad categories based upon presentation and distribution of symptoms. The first category is peripheral mononeuropathy (eg, carpal tunnel syndrome, trigeminal neuralgia, postherpetic neuralgia, and complex regional pain syndrome). The second is peripheral polyneuropathy (eg, diabetic and human immunodeficiency virus [HIV] neuropathy) and the third category is central neuropathy (eg, poststroke syndrome, spinal cord injury and HIV myelopathy).

While some types of chronic pain may be classified clearly as nociceptive or of neuropathic origin, other chronic pain disorders are of the mixed type and involve both nociceptive and neuropathic elements. An example of a mixed-type pain syndrome is chronic, recurrent headache.

For more information on Neuropathic pain and the role of Neuroscience in its treatment and diagnosis, visit our Medivision web portal at www.treatpain-info.com