Cerebral edema is a heterogeneous condition that is present in almost every type of neurological disease process--ranging from tumor, to cerebrovascular disease, to infection, to trauma, among others. It is associated with a high rate of morbidity and mortality. The pathophysiologic mechanisms of edema formation are distinct for the different conditions, thereby defining the various classifications. A relatively new treatment practice for cerebral edema is known as induced, sustained hypernatremia. This practice is highly controversial, is in widespread use, and lacks robust evidence for efficacy. Herein, we review details of the controversy regarding this practice.