1. Kimitsu Central Hospital, Kisarazu, Chiba, Japan
2. Department of Neurological Surgery, Chiba University Hospital, Chiba, Chiba, Japan
3. Rehabilitation Medicine, Chiba University, Chiba, Chiba, Japan
4. Department of Neurosurgery, Narita Red Cross Hospital, Narita, Chiba, Japan
5. Department of Neurosurgery, Higashi Chiba Medical Center, Togane, Chiba, Japan