1. Department of Minimally Invasive Surgery, Instituto de Patologia da Coluna, Vergueiro Street, 1421, Sala 305, Torre Sul, Paraíso, 04101-000 São Paulo, SP, Brazil
2. Department of Imaging Diagnosis, Universidade Federal de São Paulo, Napoleão de Barros Street, 800, Vila Clementino, 04024-002 São Paulo, SP, Brazil
3. Department of Neurosurgery, University of California, San Diego, 200 West Arbor Drive, CA 92103, USA