Design: Our primary objective is to examine the change in the level of oxidative stress by measuring the oxidative marker 8-hydroxy-2-deoxyguanosine from baseline and after 6 months of treatment with placebo or varying doses of idebenone. Following informed consent and assent, patients will undergo an initial medical history and physical followed by specific neurological, functional, and cardiac testing over a two-day outpatient visit. Patients will provide blood and urine samples for safety laboratory and biochemical analysis. Each patient will be randomized to one of 4 treatment arms and will be provided with a 6 month supply of study drug or placebo which will be administered three times a day. Patients will have follow-up laboratory monitoring after 1 and 3 months and at the end of the study. Additionally, patients will also have an EKG, vital signs, including orthostatics, and a physical examination performed after 1 and 3 months by their primary care physician. Patients will return after 6 months for follow-up exam, testing, and laboratory monitoring over a two-day outpatient visit.