Transcranial Electrical Polarization to Treat Focal Hand Dystonia

This study will evaluate the effect of transcranial electrical polarization (TEP), also called direct current (DC) stimulation, on focal hand dystonia in people with writer's cramp. In dystonia, muscle spasms cause uncontrolled twisting and repetitive movement or abnormal postures. Focal dystonia involves just one part of the body, such as the hand, neck or face. When people with focal hand dystonia make small and repeated movements with their hands, there is extra activity in the part of the brain called the motor cortex. TEP is a method of brain stimulation that slows down the activity of the nerve cells in the motor cortex. This study may help researchers develop new ways to treat focal hand dystonia. People 18 years of age and older with focal hand dystonia may be eligible for this study. Participants have a neurological examination and are randomly assigned to one of two treatment groups: TEP or placebo stimulation. The TEP group receives stimulation to the parts of the brain used for hand movement, and the placebo group receives sham stimulation, which does not affect any area of the brain. There are three TEP/placebo sessions over a period of 7 to 10 days. The first session may last up to 2-1/2 hours; the other two sessions last 1-2 hours. For TEP, sponge electrodes are placed on the scalp and an electrical current is passed through the scalp and skull to the outer part of brain. Before and after each session, participants have a neurological examination, including an evaluation of the rate and severity of their movement problems. For this assessment, participants do a writing test while the electrical activity of their hand muscles is recorded using surface electromyography (EMG). For EMG, small metal disks (electrodes) filled with a conductive gel are taped to the skin over the muscles being tested. Patients are followed in the clinic the day after the end of TEP treatment for evaluation of their movement abilities and the effects of therapy, such as imp