1. Department of Emergency Medicine Yamagata City Hospital, Saiseikan, Nanokamachi, Yamagata, Japan.
2. Department of Neurosurgery, Yamagata City Hospital, Saiseikan, Nanokamachi, Yamagata, Japan.
3. Department of Neurosurgery, School of Medicine, Yamagata University, Kojirakawamachi, Yamagata, Japan.