Cerebral water transport using multiple-network poroelastic theory: application to normal pressure hydrocephalus

The twenty-first century is bearing witness to a drastic change in population demographics and diseases of old age, such as dementia, are placing an unprecedented burden on the global healthcare system. Normal pressure hydrocephalus may be the only curable form of dementia, yet its pathophysiology is paradoxical and a consistent treatment currently remains elusive. A novel application of multiple-network poroelastic theory (MPET) is proposed to investigate water transport in the cerebral environment. Specifically, MPET is modified to allow a detailed investigation of spatio-temporal transport of fluid between the cerebral blood, cerebrospinal fluid (CSF) and brain parenchyma across scales. This framework thus allows an exploration of hypotheses defining the initiation and progression of both acute and chronic hydrocephalus. Results show that a breakdown in the transport mechanisms between the arterial vascular network and interstitial space within the parenchyma may be a cause of accumulation of CSF in the ventricles. Specifically, there must be an increase in the compliance of the arteriole/capillary network, which may combine with a breakdown in the blood-CSF barrier to allow an increased flow from the arteriole/capillary blood to the CSF. The results of this study should prove useful to guide experimental exploration in areas that warrant further investigation and validation.