1. Department of Neurosurgery, Hospital Clínica Kennedy, Guayaquil, Ecuador
2. Department of Medicine, Universidad de Especialidades Espíritu Santo, Samborondon, Ecuador,
3. Department of Neurosurgery, Clinical Hospital, Universidad de la Republica, Montevideo, Uruguay, Guayaquil, Ecuador
4. Department of Neurosurgery, Clínica Guayaquil, Guayaquil, Ecuador
5. Department of Medicine, Universidad Católica de Santiago de Guayaquil, Guayaquil, Ecuador,
6. Department of Neurosurgery, National Institute of Neurology and Neurosurgery Manuel Velasco Suarez, México City, Mexico.