Affiliation: | 1. Department of Neurosurgery, University Hospital Virgen del Rocío, Sevilla, Spain;2. Department of Neurosurgery, University Hospital of Leon, Leon, Spain;3. Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A.;4. Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A.;5. Department of Neurosurgery, Stanford University Medical Center, Palo Alto, CA, U.S.A. |