The skull is a closed bony compartment, and the brain and cerebrospinal fluid are maintained physiologically within a narrow intracranial pressure range. Any new space-occupying lesion, such as a hematoma, an injury that leads to brain swelling, or a brain tumor, can increase intracranial pressure and compress the brain. In severe cases, the brain may be squeezed down into the foramen magnum, giving it a cone shape, termed cerebral herniation, or “coning.” This may in turn compress the brainstem and upper cervical spinal cord, which can be fatal.