Botulinum neurotoxin serotype C: a novel effective botulinum toxin therapy in human.

Botulinum neurotoxin (BoNT) serotype A is commonly used in the treatment of focal dystonia. Nevertheless, some patients are or become resistant to this serotype. Consequently, other different serotypes have to be used. A comparison of the neuromuscular blockade induced by BoNT type A and C in the extensor digitorum brevis muscles of voluntary subjects was studied, by evaluating the amplitude variation over the time (until 90 days) of the compound muscular action potential elicited by supramaximal electrical stimulation of the peroneal nerve at the ankle. A very similar effect and temporal profile, was observed for each serotype. On this basis, two patients with idiopathic facial hemispasm and one with blepharospasm were treated with BoNT serotype C with very beneficial long lasting effects.