Botulinum Toxin-A Dosing Trends for Adductor Spasmodic Dysphonia at a Single Institution Over 10 Years.

Objectives: This study aimed to identify the changes in dosing of botulinum toxin-A for adductor spasmodic dysphonia (ADSD) over a prolonged period.

Study Design: This is a retrospective chart review.

Methods: One hundred thirteen subjects treated for ADSD from 2003 to 2013 were identified from a clinical database. Subject age, gender, and total injection dose amount were all recorded for all subjects who had at least 10 injections.

Results: Fifty-four subjects met criteria for inclusion. There were no age or gender differences in the starting dose for subjects. Dosing decreased significantly compared with the second dose (5.05 ± 1.623 Units), by the sixth dose (4.26 ± 1.698 Units), and continued through the 10th dose (4.08 ± 2.019 Units) (P < 0.005 for all).

Conclusions: Botulinum toxin-A dosing for ADSD decreases consistently over subsequent injections after the initial two dose titrations.