1. Graduate Program in Medicine: Surgical Sciences. Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
2. Neurosurgery Department, Cristo Redentor Hospital, Porto Alegre RS, Brazil
3. Urology Department, Hospital de Clinicas de Porto Alegre, Porto Alegre, RS, Brazil
4. Department of Neurological Surgery, São Jose Hospital, Santa Casa Hospital Complex, Porto Alegre, RS, Brazil