[1] Hyogo Med Univ, Dept Neurosurg, 1-1 Mukogawa, Nishinomiya, Hyogo 6638501, Japan
[2] Seijinkai Shimizu Hosp, Dept Neurosurg, Kyoto, Japan
[3] Natl Cerebral & Cardiovasc Ctr, Dept Neurosurg, Suita, Japan
[4] Juntendo Univ, Dept Neurosurg, Tokyo, Japan
[5] Univ Tsukuba, Fac Med, Dept Neurosurg, Ibaraki, Japan
[6] Kyoto Univ, Dept Neurosurg, Kyoto, Japan
[7] Kindai Univ, Dept Neurosurg, Osakasayama, Japan