1. Department of Neurosurgery, Medical University of Luebeck, Luebeck, Germany
2. Department of Neuropediatrics, Medical University of Luebeck, Luebeck, Germany
3. Department of Phoniatrics and Pediatric Audiology, Medical University of Luebeck, Luebeck, Germany
4. Department of Neurosurgery, Clemenshospital GmbH Münster, Münster, Germany