Objective: To determine the feasibility of a prospective study design aimed specifically at comparing the effect of onabotulinumtoxinA (BOT-A) to placebo injections on persons with Parkinson’s (PwP) suffering from medically-refractory rest tremor.

Background: Rest tremor remains one of the most disabling and medically-refractory symptoms of Parkinson’s disease. Prior publications have injected botulinum toxins into limbs affected by rest tremor, largely concluding that they can suppress tremor amplitude through multiple injection techniques. However, changes in limb function after injections have been harder to establish. Furthermore, results can be affected by weakness caused by the injections, especially when using higher doses traditionally reserved for dystonia. If we are to ever interpret future study results favorably for botulinum toxin use in PwPs, accounting for such confounders through thoughtful study design is necessary.

Method: A prospective, double-blind, randomized, controlled crossover design was used to assess changes within subjects one month after receiving BOT-A as compared to when receiving equal-volume, sham saline injections to the same muscles. The primary endpoint was the change in MDS-UPDRS rest tremor subscore at one month. Secondary endpoints included changes in the Action Research Arm Test (ARAT), a scale assessing limb function after botulinum toxin injections; change in the biometric characteristics of tremor as determined by a novel video-capturing device, including joint-to-joint amplitude variability over 3D space; change in limb muscle strength using the Medical Research Council (MRC) scale; and change in subjective tremor reports through patient diaries.

Results: A total of 16 subjects completed all study visits, and the study is closed to proceed with data analysis.

Conclusion: We believe that this pilot study proved useful in designing a protocol that is scientifically rigorous, accounts for many important confounding variables that might otherwise affect interpretation of the data, and if expanded has the potential to more definitely answer the question as to whether BOT-A serves a role for PwPs with medically-refractory rest tremor. We aim to share the findings of this investigator-initiated endeavor once analysis is completed in time for the annual congress.

References: N/A

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effectiveness-of-onabotulinumtoxina-on-reduction-of-rest-tremor-in-parkinsons-disease-a-pilot-study/