[1] Natl Inst Neurol Disorders & Stroke, NIH, Rockville, MD USA
[2] Univ Penn, Philadelphia, PA 19104 USA
[3] Harvard Univ, Childrens Hosp, Boston, MA 02115 USA
[4] Univ Calif San Francisco, Dept Neurol, San Francisco, CA 94143 USA
[5] Baylor Coll Med, Dept Neurol, Houston, TX 77030 USA
[6] Yale Univ, Sch Med, Dept Neurosurg, New Haven, CT USA
[7] Texas Childrens Hosp, Baylor Coll Med, Houston, TX 77030 USA