All patients will also have transcranial magnetic stimulation (TMS) testing. For this procedure, a very brief electrical current is passed through an insulated wire coil placed on the head, producing a magnetic pulse. The pulse travels through the scalp and skull and causes small electrical currents in the outer part of the brain. During the study, the patient will be asked to make movements, do simple tasks, or tense muscles, while the electrical activity of the muscles is recorded.