1. Department of Neurology, Neurological Institute, Nippon Medical School Chiba Hokusoh Hospital; Inzai-shi, Chiba, Japan
2. Positron Medical Center, Tokyo Metropolitan Institute of Gerontology; Itabashi-ku, Tokyo, Japan
3. Second Department of Internal Medicine, Nippon Medical School; Bunkyo-ku, Tokyo, Japan
4. Department of Neurology, The Jikei University School of Medicine; Minato-ku, Tokyo, Japan
5. Department of Internal Medicine, Nippon Medical School Musashi Kosugi Hospital; Kawasaki, Kanagawa, Japan
6. Department of Neurology and Neurological Science Graduate School, Tokyo Medical and Dental University; Tokyo, Japan
7. Department of Neurosurgery, Neurological Institute, Nippon Medical School Chiba Hokusoh Hospital; Inzai-shi, Chiba, Japan