Adolescent, Anesthesia, General, Brain Stem Neoplasms, Cerebral Ventricles, Child, Child, Preschool, Endoscopy, Female, Follow-Up Studies, Glioma, Humans, Hydrocephalus, Intracranial Hypertension, Male, Postoperative Complications, Radiography, Reoperation, Retrospective Studies, Treatment Failure, Treatment Outcome, Ventriculostomy