Advances in the Diagnosis and Management of Peripheral Nerve Disease

Abstract

Much progress has been made in the assessment and management of neuropathic pain over the past 5 years. Assessment has improved with the Neuropathic Pain Scale, a new, easily administered, diagnostic tool. Mechanistically, recent studies indicate that peripheral neuropathic pain is generated through a focal inflammatory process rather than axonal destruction. This process also appears to involve mRNA regulation of fast sodium channels, which produce ectopic discharges and are presumably responsible for pain generation. In addition the entire neuraxis undergoes neuroplastic changes as a result of peripheral nerve injury. The available clinical trial data indicate that newer antiepileptic drugs (AEDs), most notably gabapentin, are better alternatives to older medications such as carbamazepine or phenytoin in the treatment of neuropathic pain. Gabapentin is at least as good with respect to actual pain relief as the antidepressants, including amitriptyline, but has a much better safety profile with minimal drug-drug interactions and side effects. Mexiletine is a reasonable alternative agent in patients who have not had a satisfactory response to, or cannot tolerate, the AEDs or antidepressants. Long-acting opioids should be considered in patients refractory to these adjunctive agents. With the advent of the topical lidocaine patch, the first drug with an FDA-approved indication for postherpetic neuralgia, a revolutionary new agent is now available for the treatment of neuropathic pain that does not have any systemic side effects.