1. Department of Neurosurgery, The 306th Hospital of the PLA, Beijing, P.R. China
2. Department of Neurological Surgery, University of California at Davis, Davis, CA, USA
3. Department of Surgery, David Grant Medical Center, CA, USA
4. Department of Surgery, University of California at Davis, Sacramento, CA, USA
5. Clinical Investigations Facility, David Grant Medical Center, CA, USA
6. Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, China