1. Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama;
2. Division of Neuroendovascular Therapy, Department of Neurosurgery, University of Toyama, Toyama;
3. Department of Neurosurgery, National Cerebral and Cardiovascular Center, Suita, Osaka;
4. Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka; and
5. Department of Neurological Surgery, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan