1. Department of Neurosurgery, Hospital Clínica Kennedy, Guayaquil, Ecuador
2. Department of Neurosurgery, National Institute of Neurology and Neurosurgery Manuel Velasco Suarez, Mexico City, Mexico,
3. Department of Medicine, Universidad Espíritu Santo, Samborondon, Ecuador
4. Department of General Surgery, Hospital Clínica Kennedy, Guayaquil, Ecuador.