Would would happen in the case of a haemorrhage?

The cranium is basically a box, made of the correct size to hold the brain, straight forward. Any extra swelling or pressure is left with nowhere to go. The bleed either has to stop and the clot dissolve before it becomes a bigger problem or the skull needs to be drilled into to remove the blood clot, before pressure to too great. If nothing is done then the swelling forces the brain down into the spinal canal and causes what is called 'coning'. The pupils become huge and unreponsive and death follows.