[1] Yale Univ, Neurol, New Haven, CT USA
[2] Brown Univ, Providence, RI 02912 USA
[3] Univ Utah, Neurol, Salt Lake City, UT USA
[4] Univ Utah, Salt Lake City, UT USA
[5] Med Univ South Carolina, Neurol, Charleston, SC 29425 USA
[6] Yale Univ, Madison, CT USA