Safety and Efficacy of Intravenous Immune Globulin in Treating Spinocerebellar Ataxia

Inclusion Criteria:

1. Outpatients with SCA 3 diagnosed by a movement disorder specialist and confirmed by genetic testing. Three patients with each diagnosis will be enrolled.
2. Age 10 years to 50 years.
3. Able to ambulate with or without assistance for 30 feet.
4. Women of child-bearing potential must use a reliable method of contraception and must provide a negative pregnancy test at entry into the study.
5. Serum creatine kinase, complete metabolic panel, complete blood count, liver function tests, renal function tests, platelets and EKG do not reveal clinically significant abnormalities (results obtained from primary care physician and dated within the past 6 months or obtained at screening visit).
6. Stable doses of all medications for 30 days prior to study entry and for the duration of the study.
7. Stable doses of all antidepressants and vitamins (including internet purchased idebenone) for 30 days prior to study entry and for the duration of the study. Throughout the study, all possible efforts should be made to maintain stable doses of all other medications.
8. Subject permission (informed consent).

Exclusion Criteria:

1. Any unstable illness that in the investigator's opinion precludes participation in this study.
2. Use of any investigational product within the past 30 days.
3. Presence of clinically significant cardiac disease (as determined by the investigator based on EKG and echocardiogram results within the past 6 months). Specifically, an ejection fraction <40%, or a prolonged QT interval (>50% of cycle duration) will be excluded. If the investigator notes clinically significant abnormalities on the EKG or echocardiogram, the subject will be eligible IF they provide clearance from a cardiologist.
4. Presence of diabetes (as determined by blood glucose labs within the past 6 months).
5. Dementia or other psychiatric illness that prevents the subject from giving informed consent (MMSE less than 25).
6. Legal incapacity or limited legal capacity.
7. Presence of severe renal disease (estimated creatinine clearance <50 mL/min) or hepatic disease (AST or ALT>2x times normal) (as evidenced by labs reported within the past 6 months).
8. Clinically significantly abnormal WBC, hemoglobin or platelet count (as evidenced by labs reported within the past 6 months).
9. IgA deficiency (evidenced by screening lab evaluations)