The purpose of this study is to determine if intravenous immunoglobulin (IVIG) treatment significantly reduces the number of epileptic seizures in cases of autoimmune epilepsy. Potential participants will be screened at an outpatient neurology clinic visit appointment. Interested qualified potential participants will be consented and offered participation in this trial. Once consent has been obtained, and it is determined that the participant meets all inclusion criteria, the participant will be randomized to either IVIG or placebo treatment for the next 5 weeks. Participants will return to Mayo Clinic for an evaluation. Those participants that received the placebo for 5 weeks will be given IVIG in an open label fashion for 5 weeks (week 7-11) then return to Mayo Clinic for evaluation. All participants will receive monthly phone calls after they complete the IVIG treatment for a period of 1 year from the end of IVIG 5 week course.