Postherpetic Neuralgia

Postherpetic Neuralgia

Herpes zoster (shingles) is due to infection of the nervous system by varicella-zoster virus. About 15% of patients who develop shingles suffer from postherpetic neuralgia. This complication seems especially likely to occur in the elderly, when the rash is severe, and when the first division of the trigeminal nerve is affected. It also relates to the duration of the rash before medical consultation. A history of shingles and the presence of cutaneous scarring resulting from shingles aid in the diagnosis. Severe pain with shingles correlates with the intensity of postherpetic symptoms.

The incidence of postherpetic neuralgia may be reduced by the treatment of shingles with oral acyclovir or famciclovir, but this is disputed; systemic corticosteroids do not help. Zoster vaccine markedly reduces morbidity from herpes zoster and postherpetic neuralgia among older adults. Management of the established complication is essentially medical. If simple analgesics fail to help, a trial of a tricyclic antidepressant (eg, amitriptyline, up to 100–150 mg/d) in conjunction with a phenothiazine (eg, perphenazine, 2–8 mg/d) is often effective. Other patients respond to carbamazepine (up to 1200 mg/d), phenytoin (300 mg/d), or gabapentin (up to 3600 mg/d), or pregabalin (up to 300 mg/d). A combination of gabapentin and morphine taken orally may provide better analgesia at lower doses of each agent than either taken alone. Topical application of capsaicin cream (eg, Zostrix, 0.025%) is sometimes helpful, perhaps because of depletion of pain-mediating peptides from peripheral sensory neurons, and topical lidocaine (5%) is also worthy of trial. The administration of live-attenuated zoster vaccine to patients over the age of 60 years is important in preventing the occurrence of herpes zoster and thus of postherpetic neuralgia.

Posted in: Facial Pain,Postherpetic Neuralgia