1. Faculty of Medicine, Universidade de Passo Fundo, Passo Fundo, RS, Brazil
2. Department of Neurosurgery, Hospital da Cidade de Passo Fundo, Passo Fundo, RS, Brazil
3. School of Medicine, Instituto Meridional, Passo Fundo, RS, Brazil
4. Instituto de Patologia de Passo Fundo, Passo Fundo, RS, Brazil
5. Neurology and Neurosurgery Service, Passo Fundo, RS, Brazil