Topical aspirin in chloroform and the relief of pain due to herpes zoster and postherpetic neuralgia.

OBJECTIVE: To determine pain patterns and relationships in patients with herpes zoster and postherpetic neuralgia before and after topical application of aspirin dissolved in chloroform applied to the painful skin surface.
DESIGN: A consecutive series of 42 patients examined and treated in a uniform manner and followed up until their pain subsided or this management mode failed.
SETTING: An ambulatory referral private practice. PATIENTS: All patients had pain due to herpes zoster or postherpetic neuralgia and were referred for management of severe pain. None refused. INTERVENTION: Topical application of crushed aspirin tablets dissolved in chloroform. OUTCOME MEASURES: Short-Form McGill Pain Questionnaire.
RESULTS: All patients reported substantially decreased pain promptly after treatment, with maximum relief at 20 to 30 minutes and lasting 2 to 4 hours. Patients gradually decreased the use of aspirin in chloroform as pain abated.
CONCLUSIONS: Topical aspirin dissolved in chloroform is an effective means of reducing pain due to herpes zoster and postherpetic neuralgia in most patients. The locus of pain origin and analgesia induced by topical aspirin is most likely at cutaneous free-nerve ending pain receptors. The mechanism responsible for the analgesic properties of aspirin is probably not the same as that responsible for its anti-inflammatory properties.