Smartshunt: The Hydrocephalus Project

Normal Pressure Hydrocephalus (NPH) is a condition promoted by the accumulation of cerebrospinal fluid (CSF) in the cranium. This accumulation is caused by increased resistance of CSF outflow resulting in an imbalance of production and absorption of CSF. Since the skull is rigid and the brain is incompressible as well as the CSF, this condition causes the brain to be damaged as illustrated in Figure 1. The people with this condition show symptoms like gait disturbance, dementia, and urinary incontinence. The mechanism that causes the resistance of CSF outflow is not very well understood and needs to be modeled for better treatment of the condition.

Figure 1: MRI image showing deformation of the brain due to enlarged ventricles.

In the modeling of the cerebral blood flow, computational fluid dynamic (CFD) simulation will be performed for the Circle of Willis, structure of arteries responsible for distributing the blood in the brain. For the afferent arteries, ones that feed the Circle of Willis the velocity distributions will be obtained with MRI. The pressure of the carotid arteries will also be determined with tonometry. For the efferent arteries, the ones that receive blood from the Circle of Willis, the velocities will be obtained by MRI as well. With the known velocities and pressures it will be possible to obtain the pressures at the exit of the efferent arteries. The capillaries originating from this location will be lumped as well as the cerebral veins to divide the brain into compartments. For each compartment the model parameters will be obtained by using the System Identification Toolbox of MATLAB. As a result of the lumped model the local brain and fluid pressure will be obtained as inputs for further modeling of the brain and the CSF (Figure 2).

Figure 2: Flow chart of the project.

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© 2016 ETH Zurich | Imprint | 25 August 2009