Comparing Clinical and Kinematic-Based Botulinum Toxin Injections for Cervical Dystonia Therapy

Recognizing cervical dystonia (CD) movement patterns for appropriate botulinum toxin type A (BoNT-A) pattern determination depends on clinical expertise. Kinematic analysis objectively measures dystonic neck movements, and whether BoNT-A patterns determined solely using kinematics can effectively treat CD symptoms was investigated.

Twenty-two BoNT-A-naïve CD participants were randomized to receive three BoNT-A injections determined clinically ("cb") or by kinematic-based assessment ("kb"). Outcomes included the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and kinematic measures of CD motor symptoms (tonic deviation and dynamic movements) at re-injection (weeks 12, 24) and peak effect (weeks 6, 18, 30) compared to baseline.

Mean tonic deviation that returned to neutral was observed in 47% of "kb" and 31% of "cb" participants between weeks 6 and 30. Mean dynamic movements (root mean square amplitude) were significantly reduced in the "kb" group between weeks 12 and 30 compared to baseline. TWSTRS total score and motor severity were significantly reduced in the "cb" group, and disability sub-score was significantly reduced in both groups for all subsequent injections. Treatment-related side effects occurred in two "cb" and four "kb" participants.

The study indicates that kinematic-based BoNT-A injection patterns can effectively reduce CD symptoms and disability, offering valuable guidance for both novice and experienced injectors.