1. Universidad de Cartagena Facultad de Medicina, Cartagena de Indias, Colombia
2. Department of Neurosurgery, Wexner Medical Center, The Ohio State university, Columbus, OH, USA
3. All India Institute of Medical Sciences. Saket Nagar. Bhopal 462020. Madhya Pradesh (India)
4. University of Cartagena, Cartagena, Colombia