Hyperosmosis of cerebral injury.

Changes in tissue osmolarity or cerebrospinal fluid osmolarity after cerebral injury have received little attention in the literature, but osmosis may be an important cause of early cerebral edema. This paper reviews concepts and terms relating to osmosis, and reviews the few papers in the literature which have studied osmolarity after cerebral injury. In studies of both traumatic brain injury and ischemia, tissue osmolarity is elevated. Osmolarity of cerebrospinal fluid has also been shown to increase with injury. There have been no human studies examining osmolarity of tissue or cerebrospinal fluid after cerebral injury. Theoretical implications of the osmotic gradient are discussed.