Mutational falsetto is the failure of the normal drop in vocal pitch at puberty. Voice
therapy almost always achieves an appropriate pitch; however, in cases of failure, surgical treatment has also been recommended. We report a case of a 47-year-old man with an above-average fundamental frequency and a thin voice quality in the absence of any signs of
androgen insufficiency. Laryngeal examination revealed
atrophy of the vocalis muscle. Voice
therapy was unsuccessful in achieving a stable voice. Injection of 15 units of
botulinum toxin into each cricothyroid muscle initially resulted in
aphonia, but the voice returned by 1 week. Average fundamental frequency was 84 Hz at 1 week, 104 Hz at 1 month, and 100 Hz at 1 year. We hypothesize that mutational
dysphonia is an habitual dysfunction of the voice with inappropriate activation of the cricothyroid muscle and disuse of laryngeal adductor muscles. Temporary deactivation of the cricothyroid muscle enforces adoption of a more appropriate vocal mechanism.
Botulinum toxin as an adjunct to voice
therapy should be considered before surgical alteration of the glottis in patients with recalcitrant mutational falsetto.