[1] Stanford Univ, Dept Neurol, Palo Alto, CA 94304 USA
[2] Stanford Univ, Dept Pediat, Palo Alto, CA 94304 USA
[3] Stanford Univ, Dept Neurosurg, Palo Alto, CA 94304 USA
[4] Stanford Univ, Dept Human Biol, Palo Alto, CA 94304 USA
[5] Stanford Univ, Dept Hlth Res & Policy, Palo Alto, CA 94304 USA
[6] No Calif Canc Ctr, Fremont, CA USA