1. Neurosurgery Department, Medical University of Gdansk, 80-214 Gdansk, Poland
2. Scientific Circle of Neurology and Neurosurgery, Neurosurgery Department, Medical University of Gdansk, 80-214 Gdansk, Poland
3. Department of Neurosurgery, Marciniaks Hospital, 54-094 Wroclaw, Poland
4. Institute of Medicine, Opole University, 45-052 Opole, Poland