Chapter 12 - Acute Herpes Zoster and Postherpetic Neuralgia

Abstract

Herpes zoster (HZ) is a reactivation of the varicella zoster virus (VZV), a human α-herpes virus. Most cases of acute HZ, defined as an infection occurring up to 30days after rash onset with subacute HZ occurring 30–90days after rash onset, are self-limited, although patients may continue to experience pain after resolution of the rash. This condition is known as postherpetic neuralgia (PHN). VZV reactivates to cause HZ, which primarily affects both the elderly and the immunosuppressed. The clinical diagnosis of HZ is based on the clinical presentation of prodrome, with pain and the subsequent papulovesicular rash, while the differential diagnosis of the zosteriform herpes simplex must be considered. Treatment options include antiviral therapy, topical treatments, and oral medications. Antiviral therapy is used as the first-line treatment, recommended for patients with increased risk of complications with HZ. Acyclovir, famciclovir, and valacyclovir are the most used antiviral medications. Topical treatments are considered for mild pain, whereas the US Food and Drug Administration has approved two topical medications, Lidocaine and Capsaicin, for PHN. Effective treatment of PHN often requires a multimodal approach. Medication to treat pain is the cornerstone of the treatment; some antidepressants or anticonvulsants are frequently used. For intense pain, epidural steroid injections or other procedures may be beneficial. PHN can have a profound impact on any affected individual. Patients may experience a reduced quality of life because of an inability to complete activities of daily living. Patients may socialize less, resulting in decreased physical functioning and psychological well-being.