The effect of botulinum toxin A on the vocal symptoms of spastic dysarthria: a case study

The vocal symptoms of spastic dysarthria and spasmodic dysphonia have many similar features. Botulinum toxin has been used effectively to treat spasmodic dysphonia. This study was designed to determine what vocal changes occur in an individual with spastic dysarthria following Botulinum toxin A injection into the thyroarytenoid muscles. Measures were obtained preinjection and three times postinjection. Acoustic and aerodynamic results were comparable to those reported for individuals with spasmodic dysphonia. The most marked change was increased DC airflow. Despite persistent breathiness, the participant reported great satisfaction with the result, particularly because of her more appropriate loudness. In addition, everyday listeners perceived significantly less listener burden and more relaxed and pleasant vocal quality postinjection.