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