[1] Univ New Mexico, Dept Neurosurg, Albuquerque, NM 87131 USA
[2] Univ Pittsburgh, Med Ctr, Dept Neurosurg, Pittsburgh, PA USA
[3] Univ Pittsburgh, Med Ctr, Sch Nursing, Pittsburgh, PA USA
[4] Univ Pittsburgh, Stroke Inst, Dept Neurol, Pittsburgh, PA USA
[5] Michigan State Univ, Dept Neurol, Div Cerebrovasc Dis, E Lansing, MI 48824 USA