<prompt> Answer this question truthfullyWhat is the natural course, potential complications, and expected outcome of gliomatosis cerebri?  <response>: <reason> If left untreated, patients with gliomatosis cerebri may progress to develop focal neurological deficits, altered mental status, hydrocephalus, brain herniation, and ultimately death. Transformation into glioblastoma grade 4 may occur a few years later. 