Investigators at the National Institute of Neurological Disorders and Stroke (NINDS) are seeking persons affected with adductor or abductor spasmodic dysphonia, muscle tension dysphonia, and laryngeal tremor to participate in research studies aimed at developing a treatment for these disorders.

The study involves a comparison of drugs and requires an initial screening and three overnight stays at the NIH clinical center. The medication are orally administered, and nasopharyngolaryngoscopy will be performed on all participants.

To be eligible, participants must be between 18 and 80 years of age, and have either adductor or abductor spasmodic dysphonia, muscular tension dysphonia, or laryngeal tremor.  Participants should be without a history of cardiac problems, asthma, or pulmonary disease, not currently taking any psychoactive medication and not currently receiving treatment for their voice disorder or have not had treatment for 4 months. 

The study will be conducted at the National Institutes of Health (NIH)
Clinical Center in Bethesda, MD. All study-related expenses will be paid by the NIH.  The study will be carried out under testing and safety standards of the U.S. Department of Health and Human Services.