[1] Gifu Prefectural Tajimi Hosp, Dept Neurosurg, 5-161 Maehata, Tajimi, Gifu 5078522, Japan
[2] Japanese Red Cross Nagoya Daini Hosp, Dept Neurosurg, Nagoya, Aichi, Japan
[3] Japanese Red Cross Nagoya Daiichi Hosp, Dept Neurosurg, Nagoya, Aichi, Japan