1. Department of Neurosurgery; Innsbruck Medical University; Anichstrasse 35, A-6020 Innsbruck Austria
2. Department of Medical Statistics and Health Economics; Innsbruck Medical University; Innsbruck Austria
3. Department of Neuroradiology; Innsbruck Medical University; Innsbruck Austria
4. Department of Neurology; Innsbruck Medical University; Innsbruck Austria