[1] NINDS, NIH, Bethesda, MD 20892 USA
[2] Univ Utah, Sch Med, Dept Pediat Med Imaging, Salt Lake City, UT USA
[3] Univ Utah, Sch Med, Vet Affairs Med Ctr, Neurol Serv, Salt Lake City, UT USA
[4] Univ Utah, Sch Med, Dept Neurol, Salt Lake City, UT USA