Botulinum toxin (BoNT) is an established mainstay treatment for
dystonia. However, its use, especially in developing countries, is significantly limited by its cost.
Chemodenervation with muscle afferent block (MAB) using
lidocaine-
ethanol may provide a more cost-effective alternative to traditional BoNT
injections. A study comparing MAB with BoNT type-A in cases of
X-linked dystonia-Parkinsonism (XDP) having
cervical dystonia indicated a modest and short-lived efficacy with MAB, while a more robust efficacy in
dystonia and
pain parameters, lasting up to 11 weeks, was observed in the two BoNT type-A preparations (Dysport® and Botox®). In another study comparing BoNT type-A formulations for
limb dystonia of XDP, a prior MAB was used to select target muscles for toxin injection. During toxin
injections in the limb muscles, Dysport® and Botox® did not show significant differences with regard to global severity and disability scales, duration of effect, and adverse event (AE) profile.
Dysphagia was the most common AE following BoNT type-A
injections in
cervical dystonia, while weakness was the most frequent AE noted with
injections for
limb dystonia. MAB
injections carried a high incidence of
dizziness and
pain during
injections. However, because MAB is a more cost-effective alternative that can be given repeatedly, it has been used in the XDP population while awaiting funds for BoNT type-A and/or for selecting muscles for injection as a test
drug.