1. Department of Neurosurgery, Ankara Ataturk Sanatory Education and Research Hospital, Ankara, Turkey
2. Department of Anesthesiology and Critical Care, Faculty of Medicine, Dokuz Eylül University, Izmir, Turkey
3. Department of Anesthesiology and Reanimation, Ankara Sincan Education and Research Hospital, Ankara, Turkey
4. Department of Neurosurgery, Istanbul Kartal Dr Lütfi Kırdar City Hospital, Istanbul, Turkey.