1University of Pittsburgh, Pittsburgh, United States
2Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, USA
3Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai‐cho, Showa‐ku, Nagoya 466‐8550, Japan
4Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA