[1] Sapporo Teishinkai Hosp, Stroke Ctr, Dept Neurosurg, Sapporo, Hokkaido, Japan
[2] Natl Brain Ctr Hosp Prof Dr dr Mahar Mardjono, Dept Neurosurg, Jakarta, Indonesia
[3] St Josephs Hosp, Barrow Neurol Inst, Dept Neurosurg, Phoenix, AZ USA
[4] Higashi Ward, 1 Chome-3-1 Kita 33 Johigashi, Sapporo, Hokkaido 0650033, Japan