Objective: To examine the safety and efficacy of AboA in OMD

Background: OMD causes involuntary movements of the lower facial, masticatory, and lingual muscles.  The result is disability in relation to eating, speaking, swallowing, and related pain and oral mutilation. There have been no prospective therapeutic trials for this disorder.  

Methods: A 3×3 dose-finding study (phase I) followed by a single dose, prospective, single-blind trial (phase II).  Idiopathic or tardive OMD subjects who were severe enough to require injections and previously treated with botulinum toxin A (12 weeks post-injection) were evaluated and treated at baseline then evaluated again at weeks 6 & 12 in both phases.  Muscles injected were tailored to the individual’s dystonia using EMG guidance, but the AboA dose for each muscle was pre-specified. Video exams via standardized protocol were completed at each visit and rated by 3 movement disorder specialists in randomized order blinded to treatment stage. The primary efficacy outcome was change in Global Dystonia Rating scale (GDRS) for jaw/tongue from baseline to week 6.  Secondary measures included, change in GDRS for jaw/tongue from baseline to week 12, changes in Unified Dystonia Rating Scale (UDRS), total GDRS, CGI-improvement & severity by unblinded injector and quality of life (OMDQ-25) at week 6.  Adverse events were monitored.

Results: Two of three subjects completing the lowest dose in phase I developed mild adverse effects. For that reason the lowest dose level was used in the phase II. Twenty treatments (18 subjects) have been completed in phase II. The final 3 have not completed all visits at this time. Mean age 62.4 years, duration of dystonia 69.5 months and 67% were female.  11 had jaw opening dystonia, 4 jaw closing and 3 had evidence for both and 5 had concomitant lingual dystonia.  Preliminary analyses revealed adverse effects in 9, mainly mild, and included dysphagia(6), voice change(5), soft palate weakness(4). Preliminary analyses also revealed significant improvement on several secondary measures including GDRS, UDRS, and CGI Severity. 

Conclusions: This is the first prospective therapeutic trial in OMD.  AboA was generally well tolerated but the occurrence of side effects indicates a need to tailor dosing.  The results highlight some strengths and weaknesses of available scales for OMD.  A multicenter trial is warranted. 

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MDS Abstracts - https://www.mdsabstracts.org/abstract/oromandibular-dystonia-omd-a-prospective-single-blind-trial-of-abobotulinumtoxina-aboa/