Functional Ability Improved in Essential Tremor by IncobotulinumtoxinA Injections Using Kinematically Determined Biomechanical Patterns – A New FutureReport as inadecuate

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Effective treatment for functional disability caused by essential tremor is a significant unmet need faced by many clinicians today. Current literature regarding focal therapy by botulinum toxin type A BoNT-A injections uses fixed dosing regimens, which cannot be individualized, provides only limited functional benefit and unacceptable muscle weakness commonly occurs. This 38-week open label study, the longest to-date, demonstrates how kinematic technology addressed all these issues by guiding muscle selection.


Participants n = 24 were assessed at weeks 0, 6, 16, 22, 32, and 38 and injected with incobotulinumtoxinA at weeks 0, 16, and 32. Clinical assessments including UPDRS tremor items, Fahn-Tolosa-Marin FTM tremor rating scale assessing tremor severity, writing and functional ability, quality of life questionnaire QUEST and objective kinematic assessments were completed at every visit. Participants performed two postural and two weight-bearing scripted tasks with motion sensors placed over the wrist, elbow and shoulder joints. These sensors captured angular tremor amplitude RMS units and acceleration joint motion that was segmented into directional components: flexion-extension F-E, pronation-supination and radial-ulnar at the wrist, F-E at the elbow, and F-E and adduction-abduction at the shoulder. Injection parameters were determined using kinematics, followed by the clinician’s determination of which muscles would contribute to the specific upper limb tremor biomechanics and dosing per participant.


Multi-joint biomechanical recordings allowed individualized muscle selection and showed significant improvement in whole-arm function, FTM parts A-C scores, at week 6 which continued throughout the study. By week 38, the total FTM score statistically significantly reduced from 16.2±4.6 at week 0 to 9.5±6.3 p<0.0005. UPDRS item 21 score rating action tremor was significantly reduced from 2.6±0.5 at week 0 to 1.6±1.1 p = 0.01 at week 32. Quality of life QUEST significantly improved from 40.3±15.8 at week 0 to 31.1±15.3 p = 0.035 at week 32 and to 27.8±15.3 p = 0.028 at week 38. Kinematics provided an objective, secondary outcome measure, which showed a significant decrease in tremor amplitude in the wrist and shoulder joints p<0.05. Eight participants 40% self-reported mild weakness in injected muscles but had no interference in arm function.


Kinematic tremor assessments provide the injector unique insight to objectively individualize and personalize injection parameters demonstrating BoNT-A effectively alleviates functional disability caused by essential tremor. Kinematic technology is a promising method for standardizing assessments and for focal upper limb tremor treatment.

Trial Registration NCT02427646

Author: Olivia Samotus, Fariborz Rahimi, Jack Lee, Mandar Jog



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