[1] Eastern Virginia Med Sch, Dept Pediat, Norfolk, VA 23501 USA
[2] Eastern Virginia Med Sch, Dept Neurol, Norfolk, VA 23501 USA
[3] Stanford Univ, Dept Neurol, Palo Alto, CA 94304 USA
[4] Stanford Univ, Dept Pediat, Palo Alto, CA 94304 USA
[5] Stanford Univ, Dept Neurosurg, Palo Alto, CA 94304 USA
[6] Stanford Univ, Dept Human Biol, Palo Alto, CA 94304 USA