Botulinum Toxin Type A Injections as Monotherapy for Upper Limb Essential Tremor Using Kinematics

Area of Science:

• Neurology
• Biomedical Engineering
• Pharmacology

Background:

• Essential tremor (ET) lacks targeted therapies, and existing treatments are often poorly tolerated, leaving many patients undertreated.
• Kinematically guided individualized botulinum toxin type A (BoNT-A) injections show promise for ET, offering benefits with minimal weakness.
• This study presents the first long-term (96-week) safety and efficacy evaluation of BoNT-A as monotherapy for ET.

Purpose of the Study:

• To assess the long-term safety and efficacy of kinematically guided individualized botulinum toxin type A (BoNT-A) as monotherapy for essential tremor (ET).
• To evaluate the impact of BoNT-A treatment on functional tremor scores, quality of life, and grip strength in ET patients.

Main Methods:

• Ten ET patients received six serial BoNT-A treatments every 16 weeks.
• Assessments included Fahn-Tolosa-Marin (FTM) scale, Unified Parkinson's Disease Rating Scale, Quality of Life for Essential Tremor Questionnaire (QUEST), and kinematic analysis.
• Dosing was individualized based on biomechanical analysis of upper limb tremor and neurologist interpretation.

Main Results:

• Significant functional improvement (33.8% on FTM part C, p<0.05) and quality of life enhancement (39.8% on QUEST, p<0.0005) were observed at 96 weeks.
• A non-dose-dependent reduction in maximal grip strength (44.6%, p<0.0005) occurred, with only two patients reporting mild weakness.
• Action tremor scores decreased significantly in both treated (62.9%, p=0.001) and untreated (44.4%, p=0.03) arms by week 96.

Conclusions:

• Individualized BoNT-A dosing, tailored to tremor biomechanics, is an effective monotherapy for ET.
• The treatment improved patient function without causing functionally limiting muscle weakness.
• This approach offers a promising targeted therapy for essential tremor.