[1] HARVARD UNIV, MASSACHUSETTS GEN HOSP,SCH MED,DEPT NEUROL, NEUROL SERV, BOSTON, MA 02114 USA
[2] HARVARD UNIV, MASSACHUSETTS GEN HOSP, SCH MED, DEPT NEUROSURG, BOSTON, MA 02114 USA
[3] BOSTON UNIV, SCH MED, WHITAKER CARDIOVASC INST, BOSTON, MA 02114 USA