Injection of botulinum toxin type A (BOTOX) into both thyroarytenoid muscles is an accepted treatment for spasmodic dysphonia. The authors of this study identified patients who could not tolerate the interval of breathy voice that immediately follows bilateral injections. These patients were offered a protocol in which the injection side was alternated on subsequent treatments. Eighteen patients who received at least two bilateral injections and two unilateral injections were reviewed. Alternating unilateral injections yielded a shorter breathy interval by an average of 12.7 days (P=.0007) and a shorter duration of return of spasmodic symptoms by an average of 26.0 days (P=.0006). Compared with bilateral injections, alternating unilateral injections yielded an average (median) of 3.2 more days of strong voice per day of breathy voice (P=.001). However, unilateral injections had a shorter average interval of strong voice (27.4 days; P=.007), as well as a slightly higher failure rate (4.9% vs. 1.1%). The authors conclude that alternating unilateral botulinum toxin type A injections are useful in patients with spasmodic dysphonia who have difficulty with the breathy voice that follows bilateral injection.

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