1. Department of Neurology, University Hospital of Ioannina, Ioannina, Greece
2. Neurosurgical Institute, University of Ioannina, Ioannina, Greece
3. Department of Neurosurgery, University of Ioannina, Ioannina, Greece
4. Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, 19107 PA, USA
5. Department of Nuclear Medicine, University Hospital of Ioannina, Ioannina, Greece