Evaluation of Density and Pattern of Distribution of GABA A Receptors in the Brain of Patients With Focal Hand Dystonia Studied With PET Using [11C] Flumazenil

This study will examine how chemical changes in the brain produce symptoms of hand dystonia. Patients with dystonia have muscle spasms that cause uncontrolled twisting and repetitive movement or abnormal postures. In focal dystonia, just one part of the body, such as the hand, neck or face, is involved. The study will use positron emission tomography (PET) to find our which areas of the brain in patients with focal hand dystonia differ from healthy volunteers without focal hand dystonia.

Healthy volunteers and patients with focal hand dystonia between 18 and 65 years of age may be eligible for this study. Candidates are screened with a medical history and physical and neurological examinations.

Participants undergo the following procedures:

• PET scanning: The PET scanner is shaped like a doughnut. The subject lies on a bed that can slide in and out of the scanner. A custom-molded plastic mask is placed on the face and head to support the head and prevent it from moving during scanning. Two radioactive substances - five doses (one per scan) of [15 O] water and one dose of [11C] flumazil are injected into the body through a vein. The dose of injected radioactive substance is very small, and they are not harmful to the body. The [15 O] water doses are injected during the first hour and scans are taken every 10 minutes. The [11C] flumazil is injected during the second hour. The radioactive substances are detected by the PET scanner and provide information on the functioning of the brain chemistry.
• MRI scanning: MRI uses a magnetic field and radio waves to produce images of body tissues and organs. The patient lies on a table that is moved into the scanner (a narrow cylinder), wearing earplugs to muffle loud knocking and thumping sounds that occur during the scanning process. Scanning time for this study will be less than one hour. Subjects may be asked to lie still for up to 10 minutes at a time.