1 Department of Neurology, Tokyo Metropolitan Neurological Hospital, 2-6-1 Musashidai, Fuchu-Shi, Tokyo, 183-0042, Japan.
2 Department of Neurology, Tokyo Metropolitan Neurological Hospital, 2-6-1 Musashidai, Fuchu-Shi, Tokyo, 183-0042, Japan. ryoichiokiyama@kha.biglobe.ne.jp.
3 Department of Neurosurgery, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan.
4 Department of Neurosurgery, Atsugi City Hospital, Kanagawa, Japan.