1. Department of Neurosurgery, Memfys Hospital, Transekulu, Enugu, Nigeria,
2. Department of Neurosurgery, Shinshu University Hospital, Matsumoto, Japan
3. Department of Neurosurgery, Japanese Red Cross Society Suwa Hospital, Suwa, Japan
4. Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.