[1] Univ Texas, Med Branch, Div Neurosurg, Dept Neurol, Galveston, TX 77555 USA
[2] Univ Texas, Med Branch, Div Neurosurg, Dept Internal Med, Galveston, TX 77555 USA
[3] Univ Texas, Med Branch, Div Neurosurg, Dept Prevent Med & Community Hlth, Galveston, TX 77555 USA
[4] Univ Texas, Med Branch, Div Neurosurg, Dept Anesthesiol, Galveston, TX 77555 USA
[5] Univ Texas, Med Branch, Div Neurosurg, Dept Pathol, Galveston, TX 77555 USA
[6] Univ Texas, Med Branch, Div Neurosurg, Dept Anat & Neurosci, Galveston, TX 77555 USA