The Effects of Botulinum Toxin in Oromandibular Dystonia, a Meta-analysis

Objective: The purpose of this review is to investigate the safety and efficacy of therapeutic botulinum toxin (BTX) reported in the literature in oromandibular and lingual dystonias (grouped together here as OMD). Background: Oromandibular dystonia (OMD) is a focal dystonia involving the mouth, jaw, and tongue causing involuntary mouth closure or opening, deviation of the jaw, facial grimacing, or tongue movements. The phenomenon often interferes with chewing, swallowing, and speaking. Previous studies indicated that botulinum toxin (BTX) therapy may be one form of treatment in OMD. However, systematic pooling of BTX studies in OMD remains wanting. Methods: A systematic search of the literature that met the following eligibility criteria was done: (1) patients treated therapeutically with botulinum toxin type A and type B for oromandibular or lingual dystonia (2) studies of high methodological quality (systematic reviews or randomized controlled trials), and (3) outcome criteria specified as regards efficacy and safety. Results: No systematic studies on the use of BTX type B for OMD was reported, however, 6 studies on BTX type A fulfilled our entry criteria. Out of 414 patients, 330 from the pooled sample of 6 studies exhibited a favorable response to treatment (79.71%). Any “peak effect” score of 2 and above was used to indicate a favorable response. Nearly 30% of patients in the pooled sample experienced adverse events after BTX type A therapy, dysphagia being the most common. Other adverse events include weakness of the jaw, loss of smile, nasal regurgitation, jaw tremors, dryness of mouth, dysarthria, lip numbness, and pain at the site of injection. Conclusions: The results of the meta-analysis reinforce the findings that botulinum toxin therapy is both an effective and safe treatment for patients with oromandibular dystonia.