Role of Neurotransmission and Functional CNS Networks in Spasmodic Dysphonia

This study will examine how the brain controls speech in patients with spasmodic dysphonia, a voice disorder that involves involuntary spasms of muscles in the larynx (voice box), causing breaks in speech. Although the causes of spasmodic dysphonia are unknown, recent studies found changes in brain function in patients with the disorder that may play a role in its development. People between 21 and 80 years of age with adductor spasmodic dysphonia may be eligible for this study. Candidates are screened with the following procedures: Medical history and physical examination. Nasolaryngoscopy to examine the larynx. For this test, the inside of the subject s nose is sprayed with a decongestant and a small, flexible tube called a nasolaryngoscope is passed through the nose to the back of the throat to allow examination of the larynx. The subject may be asked to talk, sing, whistle and say prolonged vowels during the procedure. The nasolaryngoscope is connected to a camera that records the movement of the vocal cords during these tasks. Voice and speech recording to measure the type and severity of voice disorder. Subjects are asked questions about their voice disorder and their voice is recorded while they repeat sentences and sounds. Participants undergo positron emission tomography (PET) and magnetic resonance imaging (MRI) of the brain, as follows: PET: A catheter is placed in a vein in the subject s arm to inject a radioactive substance called a tracer that is detected by the PET scanner and provides information on brain function. \[11C\]flumazenil is used in one scanning session and \[11C\]raclopride is used in another. For the scan, the subject lies on a bed that slides in and out of the doughnut-shaped scanner, wearing a custom-molded mask to support the head and prevent it from moving during the scan. For the first scan the subject lies quietly for 60 minutes. For the second scan, the subject lies quietly for 50 minutes and is then asked to say sentences during another 50 minutes. The amount of radiation received in this study equals to a uniform whole-body exposure of 0.9 rem, which is within the dose guideline established by the NIH Radiation Safety Committee for research subjects. The guideline is an effective dose of 5 rem received per year. MRI: This procedure uses a strong magnetic field and radio waves instead of X-rays to obtain images of the brain. The subject lies on a table that slides into the scanner, a narrow metal cylinder, wearing ear plugs to muffle loud knocking sounds that occur during the scan. Images of the brain structure are obtained while the subject lies still in the machine for 10 minutes. This is followed by functional MRI (fMRI) for 60 minutes, in which pictures are taken while the subject speaks, showing changes in brain regions that are involved in speech production.