1. Department of Neurosurgery, Göztepe Education and Research HospitalMedeniyet University Istanbul Turkey
2. Cushing Neurosurgical Outcomes Centre, Department of NeurosurgeryBrigham and Women's Hospital Boston Massachusetts USA
3. Department of NeurosurgeryHaaglanden Medical Center The Hague The Netherlands
4. Department of NeurosurgeryLeiden University Medical Center Leiden The Netherlands
5. Department of NeurosurgeryUniversity of Copenhagen, Rigshospitalet Copenhagen Denmark, and Karolinska Institutet, Stockholm, Sweden