1. School of Medicine, Chung Shan Medical University, Taichung City 402, Taiwan, China
2. Department of Neurosurgery, Linkou Chang Gung Memorial Hospital, Taoyuan City 33305, Taiwan, China
3. Department of Neurosurgery, New Taipei Municipal Tu-Cheng Hospital (Built and Operated by Chang Gung Medical Foundation), New Taipei City 236, Taiwan, China
4. Department of Neurosurgery, Chung Shan Medical University Hospital, Taichung City 402, Taiwan, China