1. Collegium Medicum, WSB University, 41-300 Dabrowa Gornicza, Poland
2. Department of Neurosurgery, 5th Military Clinical Hospital with the SP ZOZ Polyclinic in Krakow, 30-901 Cracow, Poland
3. Department of Neurosurgery, Faculty of Medicine in Zabrze, Academy of Silesia, 40-555 Katowice, Poland
4. Department of Neurosurgery, Szpital sw. Rafala in Cracow, 30-693 Cracow, Poland
5. Department of Neurosurgery, Neurotraumatology and Spinal Surgery, Regional Hospital in Elblag, 82-300 Elblag, Poland
6. Institute of Health Care, National Academy of Applied Sciences in Przemysl, 37-700 Przemysl, Poland
7. New Medical Techniques Specjalist Hospital of St. Family in Rudna Mała, 36-054 Rudna Mala, Poland