When brain damage is extensive, brain herniation (see also figure Brain herniation and table Effects of Herniation) may occur; it contributes to neurologic deterioration because it does the following: Directly compresses brain tissue Blocks the blood supply to areas of the brain Increases ICP May lead to hydrocephalus by obstructing the cerebral ventricular system Results in neuronal and vascular cell dysfunction May shift brain structures from one side of the brain to the other side In addition to the direct effects of increased ICP on neuronal and vascular cells, cellular pathways of apoptosis and autophagy (which are forms of programmed cell death or destruction) can become activated.