Clinical Trials

Clinical trial and research studies are a crucial part to better understand spasmodic dysphonia. The NSDA provides information on this research study in order to further the scientific understanding of spasmodic dysphonia, but the NSDA does not endorse or recommend participation in this or any other medical research studies.

Research Trial - San Francisco, CA

A new study is enrolling in San Francisco: Timing of Neural Activity in Spasmodic Dysphonia - Researchers John Houde, PhD, Srikantan S. Nagarajan, PhD, Katherine Yung, MD, and colleagues are seeking volunteers to participate in spasmodic dysphonia research study. The main objective of this research is to determine how spasmodic dysphonia of the voice affects brain activity during speaking using state-of-the-art noninvasive neuroimaging techniques.

In this study, we seek to determine how spasmodic dysphonia (SD) of the voice affects brain activity during speaking. The study is open to patients who have been diagnosed with the adductor SD and have a history of a positive response to at least three injections of botulinum toxin (botox). Patients must also have had their last botox treatment no sooner than

three months prior to participation. The study has three sessions. First, in a 60 minute session, we measure the patient's voice characteristics at the UCSF Voice and Swallowing Center. Second, in a two-hour session, brain activity is measured using magnetoencephalography (MEG), which is completely non-invasive and silent. This is completed at the UCSF Biomagnetic Imaging Laboratory. In this portion, patients first have electrodes placed on their neck to monitor muscle activity in their larynx. Then the patient will lie on their back with their head in the MEG scanner, and speak vowels while the scanner records their brain activity. As the patient speaks, their voice is picked up by a microphone and played back to

them via earphones. Third, after the MEG experiment, in a 30-minute session, magnetic resonance imaging (MRI) of the brain is completed at UCSF Mission Bay. We prefer to run the three sessions of the study on the same day, but if necessary, they can be completed on separate days. Please contact Sarah Schneider at 415.885.3780 if you are interested in participating.


Research Trial - Boston, MA

Brain Recovery Lab at the MGH Institute of Health Professions, Boston, MA is conducting a research study titled: Multimodal Assessment of Neurophysiology in Focal Dystonia. The purpose of the study is to use magnetic resonance imaging (MRI) and transcranial magnetic stimulation (TMS) to determine the structure and excitability of the brain between healthy subjects and those diagnosed with laryngeal dystonia or spasmodic dysphonia to gain a better understanding of the cause of the disorder. TMS is a safe, non-invasive, painless procedure which allows researchers to measure the excitability of portions of the brain. A physician will place fine wire electrodes into the vocal cord muscle to monitor activity.


1. Greater than 18 years of age, but we are especially in need of people 55-70 years of age

2. Symptoms of laryngeal dystonia, spasmodic dysphonia or healthy person without dystonia

3. No history of seizure within the last two years

4. Participation includes two sessions lasting 2-3 hrs for each session. At the completion of the study you will be paid $200 (additional travel coverage might be provided)

For more information, please contact at (617) 643-6564 or