Examining the Spasmodic Dysphonia Diagnosis and Assessment Procedure (SD-DAP) for Measuring Symptom Change

This is a study of changes in voice and laryngeal function with treatment recorded using the Spasmodic Dysphonia Diagnosis and Assessment Procedure (SD-DAP). Persons with adductor spasmodic dysphonia will complete a questionnaire on the Voice Handicap Index (VHI) and ratings of speech effort as well as have their speech recorded and receive a nasolaryngoscopy examination prior to their usual treatment with botulinum toxin injection into the laryngeal muscles for their voice disorder. They will return for re-examination several weeks later after their injection and repeat each of the examinations. The purpose is to determine which items on the SD-DAP are sensitive to changes in the severity of their voice disorder. The items that show sensitivity would be those that would be useful for assessing voice outcomes in clinical trials. Some of the questions this study is trying to answer are * What is the best way to measure the severity of spasmodic dysphonia? * How does treatment of spasmodic dysphonia by botulinum toxin injection affect voice for communication in regular daily life in spasmodic dysphonia * Is change in speaking effort related to the change in severity of spasmodic dysphonia with botulinum toxin injection? Each participant in this study will be asked to do the following: * Provide a copy of medical records and medical history relating to the diagnosis of spasmodic dysphonia. * Have an examination by an otolaryngologist with a medical periscope inserted in the throat to view the voice box in action. The examination will be so it can be reviewed later by several different experts. * Complete questionnaires regarding the severity of their disorder before and after receiving their usual treatment; an injection of botulinum toxin into the laryngeal muscles. * Repeat a speech recording and laryngeal examination before and after treatment