Postherpetic Nneuralgia: Review of Treatment Modalities

Abstract

BACKGROUND: Varicella zoster virus (VZV) is the etiological agent for both varicella (chickenpox) and herpes zoster (HZ) (shingles). HZ results from the reactivation of VZV acquired during childhood. Postherpetic neuralgia (PHN) is the most common complication of HZ infection in immunocompetent patients. There is no universally accepted definition of PHN. While the mechanisms producing pain associated with PHN are not fully understood, peripheral and central processes are thought to be important.METHODS: The literature on the pathophysiology and the treatment of postherpetic neuralgia was reviewed for the past 30 years by using Index Medicus.CONCLUSIONS: Many modalities to treat PHN are available; none of them are very effective. The most commonly used modalities are tricyclic antidepressants, anticonvulsants, opioid analgesics, topical medications, physical modalities such as acupuncture and transcutaneous nerve stimulation, and nerve blocks. The tricyclic antidepressants have the most evidence supporting their role in treating PHN, although only half of the patients with PHN benefit. Recent studies support the use of opioid analgesics in PHN. There is a growing body of evidence in support of the use of gabapentin for PHN. Physical modalities and topical medications are probably most useful as adjuncts to centrally acting agents, not as a primary treatment modality. Injections (nerve blocks) are effective in relieving PHN anecdotally, although there are no controlled clinical trials showing efficacy.