Evaluation of Botulinum Toxin Type A Injection in the Treatment of Localized Chronic Pruritus.

Botulinum toxin is a neurotoxin produced by the bacterium that causes a flaccid muscle paralysis. It is currently used for aesthetic procedures and to treat focal hyperhidrosis. The botulinum toxin has also been used experimentally in many other dermatological conditions with positive results. We sought to evaluate the efficacy and safety of intradermal injection of botulinum toxin A in the treatment of localized recalcitrant chronic pruritus in lichen simplex, inverse psoriasis, post-burn itching, lichen planus (hypertrophic), and postherpetic neuralgia. This was a clinical trial study of 32 patients (12 with lichen simplex chronicus [LSC], 4 with inverse psoriasis, 4 with post-burning itch, 4 with lichen planus, 4 with hypertrophic lichen planus, and 4 with post-herpetic neuralgia). We used 2 to 3mL of unpreserved saline to dilute each vial (50 units) of botulinum toxin A. This led to a final concentration of 2 to 2.5U/0.1cc; injections were typically made into the dermis. The ages of patients in the group studied ranged from 13 to 85 years, with a mean of 37.38 years, and 59.4 percent were female. There were statistical reductions in visual analog scale in all the studied cases. Botulinum toxin A appears to be a safe and effective therapy for the improvement of localized recalcitrant itching in LSC, inverse psoriasis, burns, hypertrophic lichen planus, lichen planus, and symptoms of postherpetic neuralgia.