1. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California, and Department of Neurosurgery, Yamagata University School of Medicine, Yamagata, Japan
2. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
3. Department of Neurosurgery, Yamagata University School of Medicine, Yamagata, Japan
4. Department of Neurology, University of Cincinnati, Cincinnati, Ohio