A strained, strangled, or abnormally breathy voice in a patient with normal laryngeal anatomy. Flexible laryngoscopy reveals laryngeal tremor or spasm during respiration or vocalization. Adductor or abductor muscle spasms may cause the dysfunction. Adductor spasms respond to the injection of botulinum toxin into the thyroarytenoid muscles. Usually, the response lasts several months but provides only partial symptomatic relief.