Objective: To demonstrate efficacious and safe reduction in bilateral upper limb tremor severity by serial botulinum toxin type A injection parameters kinematically determined using a methodical dosing algorithm.

Background: One of the most common movement disorders that causes debilitating tremor is essential tremor (ET). Focal therapy has been shown to reduce tremor severity though patients lack functional benefit. Sensor technology objectively distinguishes complex movements of limb tremor which can be utilized to systematically calculate personalized injection patterns.

Methods: 21 ET participants attended 6 study visits and received treatment in both upper limbs every 12 weeks, totaling 3 injection cycles, and attended a follow-up visit 6 weeks post-treatment. Clinical rating scales to assess tremor and functionality (FTM) and kinematic assessments were completed at each visit. Participants in a seated position performed 2 postural and 2 weight-bearing functional tasks. Goniometers were placed over each arm joint to quantify tremor severity, as RMS amplitude, into directional components: flexion-extension (F/E), pronation-supination, and radial-ulnar in wrist, F/E in elbow, and abduction-adduction and F/E deviations in shoulder. Dosing and muscle selection were calculated using a dosing algorithm solely based on kinematic data.

Results: Kinematic assessment of wrist tremor during postural and weight-bearing tasks following the first treatment at week 6, severity of wrist tremor measured kinematically was statistically significantly reduced by 60.9% and 64.0%, respectively. Likewise during weight-bearing tasks, elbow and shoulder tremors were significantly reduced at week 6 by 58.2% and 33.6%, respectively. Relief of tremor was maintained 12 weeks following treatment at the time of re-injection. Handwriting and functional performance (FTM part B and C) were significantly improved by 31.8% and 38.4% at week 30, following the third treatment. No significant adverse effects were reported though participants perceived mild weakness that correlated to a mean decrease in maximal grip strength by 24.5%, 43.2%, 47.0% following the first, second and third treatments, respectively.

Conclusions: Kinematic assessment of tremor allows clinicians to standardize the assessment of multi-joint tremor and to use biomechanical readouts to automatically produce individualized injection parameters.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/individualized-botulinum-toxin-type-a-therapy-of-bilateral-upper-limb-essential-tremor-by-multi-sensor-kinematic-technology/