Madjiid Samii is currently President of the International Neuroscience Institute in Hannover, Germany, President of the China International Neuroscience Institute at the Capital Medical University, Beijing, China and President of the Iran International Neuroscience Institute at Tehran University of Medical Sciences. He was Director of the Neurosurgical Clinic at Nordstadt Hospital, Hannover, from 1977 to 2002 and Chair of Neurosurgery at the Medical School of Hannover from 1988. In 1992, he was elected as President of the International Skull Base Society (ISNS) and President of the World Federation of Skull Base Societies. He also served as President of the German Society of Neurosurgery from 1996 to 1998. Professor Samii is author of 15 neurosurgical books, numerous book chapters and more than 500 publications on peripheral nerves, spinal tumors and syringomyelia, skull base pathology, brain tumors and cranial nerve disorders. He has given more than 1000 lectures as invited and/or honoured guest of numerous national and international congresses.Venelin M. Gerganov is an associate professor and attending neurosurgeon at the International Neuroscience Institute in Hannover, Germany. He has been trained at the Neurosurgical Department of Sofia Medical University and then in Hannover under Professor Madjid Samii. His scientific and clinical interests are skull base surgery, endoscopy, intraoperative and functional imaging and neurooncology. Dr. Gerganov is author of 25 book chapters and more than 40 scientific articles in journals, referenced in Pubmed.