Evidence-based interventional pain medicine according to clinical diagnoses. 17. Herpes zoster and post-herpetic neuralgia.

Herpes zoster infection is caused by a reactivation of the latent varicella zoster virus that causes chicken pox. It appears predominantly in older adults whose immunity for the virus has waned. The natural course of the disease is usually favorable, and the symptoms disappear spontaneously within a few weeks. Some patients, however, have prolonged pain: post-herpetic neuralgia. The diagnosis of acute zoster infection is made on the clinical signs including the appearance of rash. Post-herpetic neuralgia is described as sharp, burning, aching, or shooting constantly present in the dermatome that corresponds with the earlier rash. The objectives of treating herpes zoster are: (1) acute pain reduction; (2) promotion of recovery of epidermal defects and prevention of secondary infections; and (3) reduction or prevention of post-herpetic neuralgia. The objective of the treatment of post-herpetic neuralgia is primarily pain alleviation and improvement of the quality of life. Early treatment of the infection and the pain is believed to reduce the risk for post-herpetic neuralgia. This persistent pain syndrome is difficult to treat. Antiepileptic drugs and tricyclic antidepressants are the first choice. Interventional treatments, such as epidural injections of corticosteroids and local anesthetic drugs, have an effect on the acute pain but are of limited use in preventing post-herpetic neuralgia. When conservative treatment fails in providing satisfactory relief of post-herpetic neuralgia, a sympathetic block may be considered (2 C+); if this treatment provides unsatisfactory results, spinal cord stimulation may be considered, in a study context (2 C+).