[1] Boston Univ, Sch Med, Dept Neurol, Boston, MA 02130 USA
[2] Harvard Univ, Dept Neurol, Boston, MA 02115 USA
[3] Brown Univ, Dept Neurol, Providence, RI 02912 USA
[4] Univ Pittsburgh, Dept Neurol, Pittsburgh, PA 15260 USA
[5] Univ Alabama Birmingham, Dept Neurol, Birmingham, AL 35294 USA
[6] Wake Forest Univ, Dept Neurol, Winston Salem, NC 27103 USA
[7] Univ Regensburg, Dept Neurol, D-8400 Regensburg, Germany
[8] Univ Munster, Dept Neurol, D-4400 Munster, Germany
[9] Univ Texas, Houston, TX USA
[10] Univ Washington, Dept Neurol Surg, Seattle, WA 98195 USA
[11] Inst Appl Physiol & Med, Seattle, WA USA