Computer modelling of the cerebrospinal fluid flow dynamics of aqueduct stenosis

As the craniospinal space is a pressure loaded system it is difficult to co nceptualise and understand the flow dynamics through the ventricular system . Aqueduct stenosis compromises flow, increasing the pressure required to m ove cerebrospinal fluid (CSF) through the ventricles. Under normal circumst ances, less than one pascal (1 Pa) of pressure is required to move a physio logical flow of CSF through the aqueduct. This is too small to measure usin g clinical pressure transducers. A computational fluid dynamics (CFD) progr am, CFX, has been used to model two forms of aqueduct stenosis: simple narr owing and forking of the aqueduct. This study shows that with mild stenoses , the increase in pressure required to drive flow becomes significant (86-1 25Pa), which may result in an increased transmantle pressure difference but not necessarily an increased intraventricular pressure. Severe stenoses wi ll result in both. Wall shear stresses increase concomitantly and may contr ibute to local damage of the aqueduct wall and further gliosis with narrowi ng.