[1] Univ Bern, Dept Neurosurg, Inselspital, Freiburgstr 10, CH-3010 Bern, Switzerland
[2] Harvard Med Sch, Boston Childrens Hosp, Dept Neurosurg, Boston, MA USA
[3] Harvard Med Sch, Boston Childrens Hosp, FM Kirby Neurobiol Ctr, Boston, MA USA
[4] Univ Bern, Inselspital, Dept Otorhinolaryngol Head & Neck Surg, Bern, Switzerland
[5] Univ Bern, Inselspital, Inst Diagnost & Intervent Neuroradiol, Bern, Switzerland
[6] Univ Childrens Hosp Zurich, Dept Diagnost Imaging, Zurich, Switzerland