1. Department of Neurosurgery, Moji medical center. Moji-ku, Kitakyushu 801-8502, Japan
2. Department of Neurosurgery, Kitakyushu General Hospital. Kokurakita-ku, Kitakyushu 802-8517, Japan
3. Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health Japan. Yahatanishi-ku, Kitakyushu 807-8555, Japan