Mario Ganau1, So Kato2,3, Yasushi Oshima3. 1. Department of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, Canada. mario.ganau@alumni.harvard.edu. 2. Department of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, Canada. 3. Department of Orthopedic Surgery, The University of Tokyo, Tokyo, Japan.