Plasticity in Cervical Dystonia

Study Summary

This study will identify changes that occur in the part of the brain that controls hand movements in patients with cervical (neck) dystonia. Patients with dystonia have muscle spasms that cause abnormal postures while trying to perform a movement. In focal dystonia, just one part of the body, such as the hand, neck or face, is involved. The study will compare findings in healthy volunteers and patients with cervical dystonia to learn more about the condition. Healthy volunteers and patients with cervical dystonia 18 years of age and older may be eligible to participate. Candidates are screened with a medical history and physical examination. Participants undergo the following tests: Somatosensory evoked potentials (Visits 1 and 2) This test examines how sensory information travels from the nerves to the spinal cord and brain. An electrode placed on an arm or leg delivers a small electrical stimulus and additional electrodes placed on the scalp, neck and over the collarbone record how the impulse from the stimulus travels over the nerve pathways. Transcranial Magnetic Stimulation (Visits 2, 3 and 4) This procedure maps brain function. A wire coil is held on the scalp. A brief electrical current passes through the coil, creating a magnetic pulse that stimulates the brain. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil. Nerve conduction studies (Visits 2, 3 and 4) This test measures how fast nerves conduct electrical impulses and the strength of the connection between the nerve and the muscle. Nerves are stimulated through small wire electrodes attached to the skin and the response is recorded and analyzed. Surface electromyography (Visits 2, 3 and 4) Electrodes are placed on the front and back of the neck muscles to measure the electrical activity of the muscles.