[1] Kansai Med Univ, Dept Neurosurg, 2-5-1 Shinmachi, Hirakata, Osaka 5731010, Japan
[2] Jikei Med Univ, Dept Neurosurg, Minato Ku, Tokyo, Japan
[3] Hokkaido Univ, Dept Neurol, Sapporo, Hokkaido, Japan
[4] Univ Occupat & Environm Hlth Japan, Ctr Res Aging Workforce, Kitakyushu, Fukuoka, Japan
[5] Natl Hosp Org, Matsue Med Ctr, Matsue, Shimane, Japan