Efficacy of IncobotulinumtoxinA (BoNT-A) Injections in Upper Limb Task-Specific and Position-Dependent Tremors.

BACKGROUND

Task-specific tremors (TST) and position-dependent tremors (PDT) are rare isolated focal tremors that impair fine motor control with few effective treatment options. Although botulinum neurotoxin (BoNT) is effective in other tremor syndromes, its evidence in these tremor subtypes remains limited.

OBJECTIVES

To evaluate the efficacy of serial BoNT injections on motor performance and quality of life in adults with upper limb TST and PDT.

METHODS

16 patients (12 with TST, 4 with PDT) received a median of 4 cumulative incobotulinumtoxinA (BoNT-A) injections approximately every three months. Outcomes assessed included: Fahn-Tolosa-Marin (FTM) Clinical Rating Scale for Tremor, kinematic scores derived from three-axis accelerometer measurements, and the Quality of Life in Essential Tremor (QUEST) questionnaire.

RESULTS

FTM writing tasks improved significantly (P ≤ 0.04), except for line B drawing (P = 0.06). The QUEST physical domain score significantly improved (P < 0.01). There were non-significant improvements in kinematics scores.

CONCLUSION

Serial BoNT-A injections significantly improved handwriting and patient-reported physical function in TST and PDT.