Botulinum toxin-A targeted for focal/ multifocal dystonias- An open- label application in X-linked Dystonia-Parkinsonism

ABSTRACT

Targeted for relief of spasms, posturing, pain, impaired function and disfigurement, botulinum toxin type-A (BoNT-A) was injected in dystonias of X-linked dystonia-parkinsonism (XDP). From 1992-2012, focal/ multifocal dystonia combinations were injected in XDP at the following regions: Peri-ocular (21 cases), oromandibular (50 cases), ligual (35 cases), laryngeal (5 cases), cervical (56 cases), truncalaxil (24 cases) upper limbs (13 cases) and lower limbs (18 cases). Pain was frequently reported in 40/50 cases with oromandibular dystonia, 28/56 cases with cervical dystonia, 18/24 cases with truncal-axil dystonia and 16/31 cases with limb dystonia. Outcomes were assessment through the global dystonia rating scale (DRS) at week 4, VAS pain reduction at week 4, duration of BoNT-A effects and safety. Cranial, laryngeal and cervical dystonia showed substantial improvement (DRS median score of 3-4), whereas truncal-axil and limb dystonias showed moderate improvement (DRS median score of 2), following BoNT-A. Pain reduction ranged from 30-100% (VAS), for those dystonias that reported co-morbid pain. BoNT-A effects had a duration ranging from 8-20 weeks. Procedures were generally well tolerated, and the adverse events were most significant in laryngeal injections (voice breathiness, but was eventually followed by a strong voice). The other events were mouth dryness, dysphagia and weekness in oromandibular, cervical and limb dystonias, respectively. Therefore, BoNT-A is a safe and valuable therapeutic option for the dystonias of XDP, especially the disabling and painful dystonias. BoNT-A injection working protocols could be adopted in dystonia that adheres to cost minimization (e.g. lower dose end per selected muscles), yet achieving a substantial benefit, and a reduced adverse event profile. Futhermore, this present study allowed us to recommend a "high potency, low dillution" of BoNT-A in oromandibular, linual, laryngeal, cervical and distal limb dystonias. In dystonias of the abdominal, paraspinal and proximal limb muscles, the "low potency, high dilution" BoNT-A injection protocol could be adopted.