Botulinum toxin-a treatment reduces human mechanical pain sensitivity and mechanotransduction

The mechanisms underlying the analgesic effects of botulinum toxin serotype A (BoNT-A) are not well understood. We have tested the hypothesis that BoNT-A can block nociceptor transduction. Intradermal administration of BoNT-A to healthy volunteers produced a marked and specific decrease in noxious mechanical pain sensitivity, whereas sensitivity to low-threshold mechanical and thermal stimuli was unchanged. BoNT-A did not affect cutaneous innervation. In cultured rodent primary sensory neurons, BoNT-A decreased the proportion of neurons expressing slowly adapting mechanically gated currents linked to mechanical pain transduction. Inhibition of mechanotransduction provides a novel locus of action of BoNT-A, further understanding of which may extend its use as an analgesic agent. Ann Neurol 2014;75:591-596 © 2014 The Authors. American Neurological Association.