A Prospective Crossover Trial of Botulinum Toxin Chemodenervation Versus Injection Augmentation for Essential Voice Tremor

Objectives/Hypothesis: Botulinum toxin chemodenervation (BTX) is used to treat essential voice tremor (EVT), but results are not uniformly satisfactory. This study sought to assess the comparative utility of injection augmentation (IA) for EVT. Study Design: Prospective crossover treatment study. Methods: Patients with EVT underwent BTX. After washout patients underwent IA. Multidimensional assessment carried out prior to and 30 days after each treatment included 1) videostroboscopy graded by the Vocal Tremor Scoring System (VTSS), 2) acoustic and aerodynamic assessment (cepstral peak prominence, cepstral spectral index of dysphonia, cepstral peak prominence fundamental frequency, airflow, peak air pressure and intensity, maximum phonation time, and amplitude/ frequency of tremor), 3) audio-perceptual assessment via Consensus Audio-Perceptual Evaluation of Voice (CAPE-V), and 4) patient self-assessment via Voice Handicap Index-10 (VHI-10) and Percent of Normal Function (PNF) scale. Findings were analyzed via paired t tests and Wilcoxon rank sum tests. Results: Seven patients (five female and two male; mean age 67 years old; range, 46-82 years old) participated. VTSS grading showed divergent outcomes for certain individual sites of tremor, but without significant differences. Airflow increased following BTX and decreased following IA, and VHI-10 scores indicated slight improvement post-BTX (26.2923.57), and decline post-IA (25.86-29.86), although differences were not significant. Only changes in audio-perceptual ratings of loudness achieved significance, which decreased with BTX and increased with IA. Five patients chose to resume BTX; two elected long-term IA. No findings supported patient preferences. Conclusions: IA demonstrated no advantage over BTX in the treatment of EVT.