Herpes zoster and postherpetic neuralgia. Optimal treatment.

Herpes zoster is a common disease primarily affecting the elderly. Although some individuals experience no symptoms beyond the duration of the acute infection, many develop chronic pain [postherpetic neuralgia (PHN)], which is the commonest complication of herpes zoster infection and remains notoriously difficult to treat once established. It may persist until death and has major implications for quality of life and use of healthcare resources. Predictors for the development of PHN are present during the acute disease and should indicate the need for the use of preventive therapy. At the present time, use of antiviral and certain tricyclic antidepressant drugs, combined with psychosocial support, seem most effective, but are far from perfect. Sympathetic nerve blocks reduce acute herpetic pain but it is uncertain whether they prevent PHN. In the future, vaccines may have an important place in reducing the incidence of chickenpox in the population or, through the vaccination of middle-aged individuals, in boosting immunity to varicella zoster virus, thus preventing or modifying the replication of the virus from its latent phase that results in herpes zoster. Developments in the understanding of the pathophysiology of PHN indicate possible directions for improved drug management of established PHN, although no evidence yet exists for efficacy of the drugs concerned. Such agents include new generation anticonvulsants and N-methyl-D-aspartate antagonists.