Adolescent Age Factors Age of Onset Australia--epidemiology Brain Diseases--diagnosis Brain Neoplasms--complications Child Child, Preschool Cross-Cultural Comparison Electrodes, Implanted--statistics & numerical data Electroencephalography--statistics & numerical data Epilepsy--diagnosis Europe--epidemiology Fluorodeoxyglucose F18 Health Care Surveys--statistics & numerical data Hemispherectomy--statistics & numerical data Humans Magnetic Resonance Imaging Neurosurgical Procedures--methods Preoperative Care Reoperation--statistics & numerical data Tomography, Emission-Computed, Single-Photon United States--epidemiology Vagus Nerve--physiology