This study will examine the role of certain areas of the brain in blepharospasm, a type of dystonia (abnormality of movement and muscle tone) that causes unwanted or uncontrollable blinking or closing of the eyelids. The study will compare brain activity in healthy volunteers and in people with blepharospasm to find differences in the brain that may lead to better treatments for dystonia.

Healthy volunteers and people with blepharospasm who are 18 years of age and older may be eligible for this study. All candidates are screened with a medical history. People with blepharospasm also have a physical examination and blepharospasm rating.

Participants undergo transcranial magnetic stimulation (TMS) and electromyography (EMG) in two 4-hour sessions, separated by 1 to 7 days.

TMS

A wire coil is held on the subject's scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. The subject hears a click and may feel a pulling sensation on the skin under the coil. There may be a twitch in muscles of the face, arm or leg. During the stimulation, subjects may be asked to tense certain muscles slightly or perform other simple actions. Repetitive TMS involves repeated magnetic pulses delivered in short bursts of impulses. Subjects receive 60 pulses per minute over 15 minutes.

EMG

Surface EMG is done during TMS to measure the electrical activity of muscles. For this test, electrodes (small metal disks) are filled with a conductive gel and taped to the skin of the face.