Acute herpes zoster and postherpetic neuralgia: effects of acyclovir and outcome of treatment with amitriptyline.

This retrospective study was designed to assess the effects of acyclovir treatment of acute herpes zoster on subsequent postherpetic neuralgia, and to examine the effects of amitriptyline in the treatment of postherpetic neuralgia. Eighty seven patients with postherpetic neuralgia of three or more months' duration were studied: 24 of them had had their herpes zoster treated with oral acyclovir. At first presentation, only 25% of the 24 patients who had had their herpes zoster treated with acyclovir selected the word group containing burning on the McGill pain questionnaire compared with 76% of the 63 patients who had not received acyclovir. A higher proportion of patients who had had acyclovir than had not selected the word group which contains the word aching (63% versus 49%). Acyclovir thus appears to change the nature of postherpetic neuralgia. Postherpetic neuralgia was treated with amitriptyline, alone or in combination with distigmine and/or sodium valproate. There was a strong correlation between pain relief and the interval between the occurrence of herpes zoster and the initiation of treatment with amitriptyline--early treatment is almost twice as likely to be successful as late. Since conventional analgesics and sympatholytic drugs are of no benefit in the treatment of established postherpetic neuralgia, the sequelae of herpes zoster must, therefore, be recognized and treated with amitriptyline as soon as possible.