1. Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital;
2. School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China;
3. Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia;
4. Department of Neurosurgery, University of Pittsburgh, Pennsylvania; and
5. Unit of Radiosurgery, Ruber International Hospital, Madrid, Spain