Laryngeal image analysis following botulinum toxin injections in spasmodic dysphonia.

The injection of botulinum toxin (BT) into laryngeal muscles has proven to be an effective treatment for spasmodic dysphonia (SD), a neurologic disorder characterized by intermittent vocal spasms during speech. BT treatment has reduced abnormal laryngeal muscle hyperactivity in SD patients, when measured by subjective visual rating scales. This paper utilizes images obtained from endoscopic laryngeal video recordings to quantify changes in pre- and post-injection parameters of 17 patients following bilateral BT injections. A previous study, utilizing perceptual, acoustic, and laryngeal aerodynamic measures, showed significant improvements following treatment with BT. In addition, post-injection vocal rest, rather than vocalization, enhanced therapeutic responses. Results of these measures are compared with data from the image analyses and those parameters that proved to be the most useful are highlighted.