Giyas Ayberk1, Mehmet Faik Ozveren2, Mesut Emre Yaman3, Hakan Tosun2. 1. Department of Neurosurgery, Ataturk Training and Research Hospital, 06800 Bilkent, Ankara, Türkiye. giyas67@hotmail.com. 2. Department of Neurosurgery, Ataturk Training and Research Hospital, 06800 Bilkent, Ankara, Türkiye. 3. Department of Neurosurgery, Kecioren State Hospital, Ankara, Türkiye.