3 research outputs found
Intracranial volumetric changes govern cerebrospinal fluid flow in the Aqueduct of Sylvius in healthy adults
Purpose: To characterize the intracranial volumetric changes that influence the cerebrospinal fluid (CSF) pulse in the Aqueduct of Sylvius (AoS). Materials and Methods: Neck MRI data were acquired from 12 healthy adults (8 female and 4 males; mean age=30.9 years), using a 1.5 Tesla scanner. The intracranial arterial, venous and CSF volumes changes, together with the aqueductal CSF (aCSF) volume, were estimated from flow rate data acquired at C2/C3 level and in the AoS. The correlations and temporal relationships among these volumes were computed. Results: The aCSF volumetric changes were strongly correlated (r = 0.967, p<0.001) with the changes in intracranial venous volume, whose peak occurred 7.0% of cardiac cycle (p = 0.023) before peak aCSF volume, but less correlated with the intracranial arterial and CSF volume changes (r=-0.664 and 0.676 respectively, p<0.001). The intracranial CSF volume change was correlated with the intracranial venous volume change (r=0.820, p<0.001), whose peak occurred slightly before (4.2% of CC, p=0.059). Conclusion: The aCSF pulse is strongly correlated with intracranial venous volume, with expansion of the cortical veins occurring prior to aCSF flow towards the third ventricle. Both caudal-cranial aCSF flow and venous blood retention occur when arterial blood volume is at a minimum
Increased Intracranial Pressure Attenuates the Pulsating Component of Cerebral Venous Outflow
Background: The underlying physiology of the intracranial pressure (ICP) curve morphology is still poorly understood. If this physiology is explained it could be possible to extract clinically relevant information from the ICP curve. The venous outflow from the cranial cavity is pulsatile, and in theory the pulsatile component of venous outflow from the cranial cavity should be attenuated with increasing ICP. In this study, we explored the relationship between ICP and the pulsatility of the venous outflow from the intracranial cavity. Methods: Thirty-seven neuro-intensive care patients that had been examined with phase-contrast magnetic resonance imaging regarding cerebral blood flow (CBF) through the internal carotid and vertebral arteries and venous flow in the internal jugular veins were retrospectively included. The pulsatility of the jugular flow was determined by calculating the venous pulsatile index. The results were correlated to clinical data registered in the patient data monitoring system, including ICP and cerebral perfusion pressure (CPP). Results: CBF was 996 ± 298 ml/min, and the flow in the internal jugular veins equaled 67 ± 17% of the CBF, with a range of 22–97%. The venous pulsatile index correlated negatively to ICP (R = − 0.47 p = 0.003). The lowest flow in the internal jugular veins over the cardiac cycle (Fmin) was not correlated to ICP. Temperature, end-tidal CO2, MAP, and CPP were not correlated to venous pulsatility. Conclusion: An increase in ICP correlates to a lower pulsatility of the venous outflow from the cranial cavity. A lower pulsatility could be due to increased pressure requirements to compress intracranial veins with increasing ICP
Analysis of Growing Tumor on the Flow Velocity of Cerebrospinal Fluid in Human Brain Using Computational Modeling and Fluid-Structure Interaction
Cerebrospinal fluid (CSF) plays a pivotal role in normal functioning of
Brain. Intracranial compartments such as blood, brain and CSF are
incompressible in nature. Therefore, if a volume imbalance in one of the
aforenoted compartments is observed, the other reaches out to maintain net
change to zero. Whereas, CSF has higher compliance over long term. However, if
the CSF flow is obstructed in the ventricles, this compliance may get exhausted
early. Brain tumor on the other hand poses a similar challenge towards
destabilization of CSF flow by compressing any section of ventricles thereby
ensuing obstruction. To avoid invasive procedures to study effects of tumor on
CSF flow, numerical-based methods such as Finite element modeling (FEM) are
used which provide excellent description of underlying pathological
interaction. A 3D fluid-structure interaction (FSI) model is developed to study
the effect of tumor growth on the flow of cerebrospinal fluid in ventricle
system. The FSI model encapsulates all the physiological parameters which may
be necessary in analyzing intraventricular CSF flow behavior. Findings of the
model show that brain tumor affects CSF flow parameters by deforming the walls
of ventricles in this case accompanied by a mean rise of 74.23% in CSF flow
velocity and considerable deformation on the walls of ventricles