1. Department of Neurosurgery, Tokushima University Hospital, Tokushima;
2. Department of Neurosurgery, Shikoku Medical Center for Children and Adults, Zentsuji, Kagawa;
3. Department of Spine, Spinal Cord, Peripheral Nerve Surgery, Shin-yurigaoka General Hospital, Kawasaki, Kanagawa;
4. Department of Neurosurgery, Kitajima Taoka Hospital; and
5. Department of Neurosurgery, Yoshinogawa Hospital, Itano, Tokushima, Japan