1. Department of Neurology and Neurosurgery, McGill Scoliosis & Spine Group, McGill University, Montreal, QC, Canada
2. Universidade de Caxias do Sul, Caxias do Sul, RS, Brazil
3. Department of Neurosurgery, Universidade de Caxias do Sul, Caxias do Sul, RS, Brazil
4. Hospital São José - Santa Casa de Porto Alegre, Porto Alegre, RS, Brazil