Prognostic factors of postherpetic neuralgia.

The investigation was aimed to determine prognostic factors related to postherpetic neuralgia (PHN), and treatment options for preventing PHN. The data showed 34 (17.0%) out of 188 patients with herpes zoster had severe pain after 4 weeks, and 22 (11.7%) after 8 weeks, compared with 109 (58.0%) at presentation. The age (>/=50 yr), surface area involved (>/=9%), and duration of severe pain (>/=4 weeks) might be the main factors that lead to PHN. On the other hand, gender, dermatomal distribution, accompanied systemic conditions, and interval between initial pain and initiation of treatment might not be implicated in PHN. The subjects were orally received antiviral (valacyclovir), tricyclic antidepressant (amitriptyline), and analgesic (ibuprofen) as the standard treatment in the group 1. In addition to the standard medication, lidocaine solution was sub- and/or perilesionally injected in the group 2, while lidocaine plus prilocaine cream was topically applied to the skin lesions in the group 3. The rates of PHN in the 3 treatment groups were not significantly different, suggesting adjuvant anesthetics may not be helpful to reduce the severity of pain.