ABSTRACT
The modified Monro-Kellie model of factors contributing to intracranial pressure (ICP) is based on a number of simplifying hypotheses. The skull is a fixed volume box (except in young children) so the intracranial volume is assumed to have a fixed overall value. Therefore, any change in volume of intracranial components [blood, brain parenchyma, CSF (CSF)] or the addition of abnormal volume (tumour, haematoma, air) must be offset by equal change in another component, or the pressure will rise.
