Persistent VZV Ganglionitis May Be the Cause of Postherpetic Neuralgia
The cause of postherpetic neuralgia (PHN) is unknown. Besides PHN, two other qualitatively identical closely related forms of radicular pain without rash are associated with VZV infection. The first is prolonged radicular pain preceding zoster rash (preherpetic neuralgia). The second is chronic radicular pain associated with VZV infection without rash (zoster sine herpete). These collective clinical conditions alone suggest that PHN results from a smoldering VZV ganglionitis. There have been only two instances in which ganglia from PHN patients before death, corresponding to the area of pain during life, were analyzed pathologically. In both, an inflammatory response in ganglia of these subjects raised the possibility of prolonged viral infection. This chapter details cases of PHN in which VZV DNA and proteins were detected in the blood of many patients with PHN. Also, cases of zoster sine herpete that were studied virologically provide evidence of a productive VZV ganglionitis. Finally, a favorable response to antiviral treatment of patients with zoster sine herpete and some with PHN provides evidence that PHN is caused by chronic active VZV infection in ganglia. Because only a few studies have used antiviral therapy to treat PHN with conflicting results, larger, double-blinded studies, which give antiviral therapy intravenously, are needed.
Supported in part by the National Institutes of Health Grants NS093716 (Gilden), AG032958 (Gilden and Nagel), and NS094758 (Nagel). The authors thank Marina Hoffman for editorial review and Cathy Allen for manuscript preparation.
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