[1] Penn State Univ, Hershey Med Ctr, Dept Neurol, Hershey, PA 16801 USA
[2] Penn State Coll Med, Dept Publ Hlth Sci, Hershey, PA USA
[3] Penn State Coll Med, Dept Radiol, Hershey, PA USA
[4] Penn State Coll Med, Coll Med, Hershey, PA USA
[5] Univ Cape Town, Cape Town, South Africa
[6] South African Med Res Council, Cape Town, South Africa
[7] Emory Univ, Dept Neurol, Atlanta, GA USA