The management of post-herpetic neuralgia

If early treatment fails, patients should be referred to pain clinics

General practice p 794

Shingles, or herpes zoster, may occur at any stage in a person's life. Herpes zoster is the clinical manifestation of the reactivation of a lifelong latent infection with varicella zoster virus, usually contracted after an episode of chickenpox in early life.1 Varicella zoster virus tends to be reactivated only once in a lifetime, with the incidence of second attacks being <5%.2 Herpes zoster occurs more commonly in later life (as T cell immunity to the virus wanes) and in patients who have T cell immunosuppression.

Pain persisting after herpes zoster, termed post-herpetic neuralgia, is the commonest and most feared complication. Its definition is controversial, ranging from pain persisting after the rash heals to pain persisting 30 days or 6 months after the onset of herpes zoster. Some experts consider all pain during and after herpes zoster as a continuum. Therefore we have suggested that this total duration of pain and pain at a single time point (3 months after onset) be used as endpoints in clinical studies.3 Post-herpetic neuralgia is associated with scarring of the dorsal root ganglion and atrophy of the dorsal horn on the affected side, which follows the extensive inflammation that occurs during herpes zoster. These and other abnormalities of the peripheral and central …