This study examined
botulinum toxin type A (BTX-A) treatment of adductor spasmodic
dysphonia patients who had previously undergone recurrent laryngeal nerve section that failed to control symptoms. Information was retrieved from records of patients treated by our group between 1984 and 1999. Complete records with standardized outcome measurements were available for 181 BTX-A injection sessions in 16 patients who had had nerve section. These were compared to previously published information regarding 4,621 sessions in 639 adductor spasmodic
dysphonia patients also treated by our group. Treatment with BTX-A resulted in significant improvement in voice function in the studied patients (change, 38.2% +/- 24.5%; p < .0001). The onset of effect took place approximately 2.3 days
after treatment, and the peak effect about 10.0 days
after treatment. The
therapeutic effect lasted 14.1 weeks on the average. These features were not significantly different from those observed in adductor spasmodic
dysphonia patients as a whole. The incidence of complications was also comparable. However, lower baseline and peak posttreatment perceptions of voice function in the nerve section group were statistically significant (baseline, 45.6% +/- 23.0% versus 52.4% +/- 22.0%; peak, 83.8% +/- 16.4% versus 89.7% +/- 13.0%; both p < .001). We conclude that BTX-A is effective in the treatment of adductor spasmodic
dysphonia in patients who have had recurrent nerve section. However, nerve section may adversely affect perceived voice function and may make
botulinum toxin therapy less satisfactory. Because of this finding, and because of the unusual pathological features of the
focal dystonias, irreversible means of treating adductor spasmodic
dysphonia should be approached with caution.