1. Department of Neurosurgery, Koc University Hospital, 34010 Istanbul, Turkey
2. Spine Center, Koc University Hospital, 34010 Istanbul, Turkey
3. Medical Faculty, Koc Univesity School of Medicine, 34010 Istanbul, Turkey
4. Department of Orthopaedics and Traumatology, Koc University Hospital, 34010 Istanbul, Turkey
5. Department of Neurosurgery, American Hospital, 34010 Istanbul, Turkey
6. Department of Physical Medicine and Rehabilitation, American Hospital, 34010 Istanbul, Turkey