1. Zentrum für Operative Medizin II, Heinrich-Heine-Universität, Düsseldorf, Germany; Department of Neurosurgery, Son Dureta University Hospital, Palma de Mallorca, Spain; Divisione di Neurochirurgia, Ospedale Bellaria C. A. Pizzardi, Bologna, Italy; Department of Pediatric Neurosurgery, Hôpital des Enfants, La Timone, Marseille, France; Department of Neurosurgery, University Clinic Innsbruck, Innsbruck, Austria; and Department of Neurological Surgery, UZ Gasthuisberg, Leuven, Belgium