[1] Baystate Med Ctr, Div Neurosurg, Springfield, MA USA
[2] Tufts Univ, Sch Med, Dept Neurosurg, Boston, MA 02111 USA
[3] Tufts Univ, Sch Med, Dept Neurol, Boston, MA 02111 USA
[4] Vanderbilt Univ, Dept Neurol Surg, Nashville, TN 37235 USA
[5] Vanderbilt Univ, Dept Radiol, Nashville, TN 37235 USA
[6] Ohio State Univ, Med Ctr, Dept Neurol Surg, Columbus, OH 43210 USA