[1] Tohoku Univ, Dept Neurosurg, Grad Sch Med, Sendai, Japan
[2] Kitasato Univ, Sch Med, Dept Neurosurg, Sagamihara, Japan
[3] Sapporo Med Univ, Dept Neurosurg, Sch Med, Sapporo, Japan
[4] Iwate Med Univ, Dept Urol, Shiwa, Iwate, Japan
[5] Fujita Hlth Univ, Dept Neurosurg, Toyoake, Japan
[6] Fukuoka Univ, Dept Neurosurg, Fukuoka, Japan
[7] Akita Univ, Grad Sch Med, Dept Neurosurg, Akita, Japan
[8] Yamagata Univ, Fac Med, Dept Neurosurg, Yamagata, Japan
[9] Univ Yamanashi, Interdisciplinary Grad Sch Med & Engn, Dept Neurosurg, Yamanashi, Japan
[10] Kyoto Univ, Grad Sch Med, Dept Neurosurg, Kyoto, Japan
[11] Okayama Univ, Grad Sch Med Dent & Pharmaceut Sci, Dept Neurol Surg, Okayama, Japan
[12] Hirosaki Univ, Grad Sch Med, Dept Neurosurg, Hirosaki, Japan
[13] St Marianna Univ, Sch Med, Dept Neurosurg, Kawasaki, Japan
[14] Niigata Univ, Brain Res Inst, Dept Neurosurg, Niigata, Japan
[15] Yamaguchi Univ, Sch Med, Dept Neurosurg, Ube, Japan
[16] Saga Univ, Fac Med, Dept Neurosurg, Saga, Japan
[17] Kagoshima Univ, Grad Sch Med & Dent Sci, Dept Neurosurg, Kagoshima, Japan
[18] Miyagi Canc Ctr, Dept Gastroenterol, Natori, Japan
[19] Teikyo Univ, Mizonokuchi Hosp, Kawasaki, Kanagawa, Japan
[20] Osaka Med & Pharmaceut Univ, Dept Neurosurg, Takatsuki, Japan
[21] Natl Hosp Org Sendai Med Ctr, Dept Pathol & Lab Med, Sendai, Miyagi, Japan
[22] Univ Texas Houston, Dept Pathol & Lab Med, Houston, TX USA
[23] Tohoku Univ, Grad Sch Med, Dept Radiat Oncol, Sendai, Japan
[24] Nagoya Univ, Grad Sch Med, Dept Neurosurg, Nagoya, Japan
[25] Tohoku Univ, Grad Sch Med, Div Biostat, Sendai, Japan