[1] Childrens Hosp, Birmingham, AL 35233 USA
[2] Univ Alabama, Dept Cell Biol, Birmingham, AL USA
[3] Univ Alabama, Sect Pediat Neurosurg, Birmingham, AL USA
[4] Univ Alabama, Div Neurosurg, Birmingham, AL USA
[5] Childrens Mem Hosp, Colorado Springs, CO USA