[1] Johns Hopkins Sch Med, Dept Anesthesia & Crit Care Med, Baltimore, MD USA
[2] Johns Hopkins Sch Med, Baltimore, MD USA
[3] Johns Hopkins Sch Med, Dept Neurol, Baltimore, MD USA
[4] NINDS, Stroke Branch, NIH, Bldg 36,Rm 4D04, Bethesda, MD 20892 USA
[5] Johns Hopkins Sch Med, Dept Radiol, Div Pediat Radiol & Pediat Neuroradiol, Baltimore, MD USA
[6] Johns Hopkins Sch Med, Div Pediat Neurol, Baltimore, MD USA