Acute Herpes zoster Neuralgia: Retrospective Analysis of Clinical Aspects and Therapeutic Responsiveness

Abstract

Background: Although the efficacy of modern antiviral agents for the treatment of herpes zoster is unquestioned, their ability to affect the associated pain remains controversial. Objective: We have therefore evaluated the inpatient hospital records of 550 patients with herpes zoster with regard to pain-related clinical aspects and therapeutic responsiveness. Methods: Intensity of pain was quantified by calculating a daily pain equivalence index (PEI) on the basis of different classes of pain medication and the number of tablets used in each category. Results: The mean age of patients was 66.7 years, cranial segments were predominantly involved (55%), 64% of patients suffered from associated diseases and 77% experienced herpes-related pain. The PEI was 0.90 in the entire patient population, with significantly higher values in women and in patients with 3 or more associated diseases. It was lower in sacral and cranial nerve involvement, and it decreased rapidly in patients prior to discharge from hospital. Although there were significant differences in hospital stay between patients who received aciclovir and those who did not (mean 20.3 vs. 23.8 days), and for high- versus low-dose oral or intravenous administration, no significant differences were noted between the two groups for initial PEI values and during the course of observation, irrespective of the route of administration or the dose of aciclovir and the individual patient’s PEI value. The groups were otherwise closely similar with regard to basic demographic and clinical data. 23.3% predominantly aged female patients with more associated diseases than the total patient population had a persistently elevated PEI and stayed in hospital beyond 21 days (mean 35.1 days), representing patients who went on to postherpetic neuralgia. Conclusion: These data further delineate clinical aspects of acute herpes zoster neuralgia, underline the unsolved therapeutic problems associated with this condition despite otherwise effective antiviral treatment, and characterise a subgroup of patients at risk to develop postherpetic neuralgia.