Objectives/hypothesis: To evaluate the influence of age and gender on the required dose and resulting efficacy of botulinum toxin injection for adductor laryngeal dystonia.
Design: Retrospective chart review.
Methods: All patients treated with botulinum toxin for laryngeal dystonia at the University of Washington Medical Center between 1991 and 2008 were identified from a large clinical database. Only patients undergoing thyroarytenoid muscle injection for adductor laryngeal dystonia were included in this study. Each patient's gender, age at treatment, stable dose of botulinum toxin, and patient-reported duration of beneficial effect was recorded.
Results: A total of 155 patients (50 males, 105 females) were identified, with average ages of 50.6 years for men and 54.4 years for women. The mean treatment doses of botulinum toxin were 1.85 +/- 0.84 U for males and 2.15 +/- 1.40 U for females. The associated mean durations of beneficial effect were 12.8 +/- 7.7 weeks for males and 13.9 +/- 7.3 weeks for females. Neither the difference in dose nor in duration was found to be statistically significant (P = .395 and P = .511, respectively). When analyzed by age, the mean doses of botulinum toxin were 1.87 +/- 1.00 U for patients younger than 50 years and 2.20 +/- 1.41 U for the older group. The associated mean durations of beneficial effect were 13.7 +/- 7.4 weeks for the younger group and 13.5 +/- 7.4 weeks for the older group. Again, neither difference was found to be statistically significant (P = .113 and P = .730, respectively).
Conclusions: Dosage and duration of beneficial effect of botulinum toxin in treatment of adductor laryngeal dystonia do not appear to vary with age or gender.