1. University of Ulsan College of Medicine Department of Neurological Surgery, Asan Medical Center, , Seoul , Korea
2. Kyungpook National University Hospital, Kyungpook National University Department of Pathology, School of Medicine, , Daegu , Korea
3. Kyungpook National University Hospital, Kyungpook National University Department of Neurosurgery, School of Medicine, , Daegu , Korea
4. Kyungpook National University Chilgok Hospital, Kyungpook National University Department of Neurosurgery, School of Medicine, , Daegu , Korea