Electrical or magnetic nerve stimulation enhance the BoNT/A-mediated muscle paralysis

Botulinum toxin type A (BoNT/A) is first-line treatment for muscle spasticity but the dose can be limited by side effects depending on the treated muscle mass and location. Stimulation of peripheral motor nerves upon BoNT/A injection into the innervated muscles may be a technique to increase the BoNT/A effect without increasing the dose. Our goal was to study the augmentation of the BoNT/A effect by transcutaneous electrical (TENS) or magnetic nerve stimulation (MS) in a mouse model.

The paralytic effect of BoNT/A with or without TENS was evaluated with the mouse digit abduction score (DAS) at 20, 30, and 40 U/kg. The paralytic effect of BoNT/A with or without peripheral MS was evaluated with the mouse DAS at 20 or 30 U/kg.

After 20 U/kg BoNT/A treatment combined with TENS the DAS was higher and showed a longer duration of paralysis than without TENS. After 30 U/kg BoNT/A treatment combined with magnetic stimulation the DAS was higher than without magnetic stimulation.

We established an electrical and a magnetic nerve stimulation protocol combined with BoNT/A treatment in mice. Combination of i.m. BoNT/A injection with TENS or MS demonstrated an enhanced BoNT/A effect as compared to non-stimulated groups. Despite limitations of the magnetic stimulation method in the mouse our data revives the discussion of BoNT/A effect augmentation by stimulating the injected muscles' efferent nerves during the BoNT/A uptake phase.