Improvement of postherpetic neuralgia after treatment with intravenous acyclovir followed by oral valacyclovir.

BACKGROUND Postherpetic neuralgia (PHN) is a complication of shingles (herpes zoster), a painful rash due to varicella-zoster virus reactivation. Studies of patients with PHN and zoster sine herpete (radicular pain without rash) support the notion that low-grade viral ganglionitis contributes to pain. If chronic pain reflects active infection, then antiviral therapy may help patients with PHN. OBJECTIVE To determine whether antiviral treatment helps reduce PHN-associated pain. DESIGN Prospective, open-label phase I/II clinical trial. SETTING Tertiary care university hospital. PATIENTS Fifteen patients with moderate to severe PHN. INTERVENTIONS Intravenous acyclovir at a dosage of 10 mg/kg every 8 hours for 14 days followed by oral valacyclovir at a dosage of 1000 mg 3 times per day for 1 month. MAIN OUTCOME MEASURE Numeric Rating Scale for Pain score. RESULTS As defined by a decrease of 2 or more points on the Numeric Rating Scale for Pain, 8 (53%) of 15 patients reported improvement. CONCLUSION Clinical improvement reported by most of our patients warrants further investigation in a larger, randomized, double-blind, placebo-controlled trial.