The experimental methodology is aimed at altering the intracranial compartment compliance by placing the patient in various positions so that these phase differences can be detected. The simplest way to alter intracranial compliance is to make postural changes. When a patient is in the Trendelenburg position, venous outflow out of the brain is hindered resulting in an increase in ICP and presumably a reduction in compliance. Conversely, raising the head of bed to 60 degrees will result in the opposite effect. The second mechanism of altering compliance (and ICP) will occur as a result of treating the hydrocephalus with a CSF shunt. Because we are able to study hydrocephalus patients prior to shunting as part of their diagnostic workup, we create a new state with the shunt that will allow us to further characterize the intracranial system.