[1] Univ Pittsburgh, Med Ctr, Stroke Inst, Dept Neurol, Pittsburgh, PA 15213 USA
[2] Univ Pittsburgh, Med Ctr, Dept Neurosurg, Pittsburgh, PA 15213 USA
[3] Univ Pittsburgh, Med Ctr, Dept Radiol, Pittsburgh, PA 15213 USA
[4] VA Hlth Syst Pittsburgh, Pittsburgh, PA USA
[5] SUNY Buffalo, Dept Neurosurg, Buffalo, NY 14260 USA