DOI: 10.14457/tu.the.2015.1361
title: Mathematical modeling of CSF dynamic force and quantification of CSF velocity at the narrowest point of aqueduct of Sylvia by CFD analysis

description: Comprehensive knowledge in Cerebral spinal fluid dynamic behavior in brain would help to precisely explain about its pathological conditions such as Normal pressure hydrocephalus and after effects of traumatic brain injuries since root causes of these diseases are still controversies. Incognizance in circumstances of above disease leads to thousands of deaths per year from all over the earth. Especially, the Normal pressure hydrocephalus which is known as severe disorder condition mostly occur among elderly persons is not well defined. Typically, causes of the Normal pressure hydrocephalus is described as imbalance of Cerebral Spinal Fluid (CSF) formation and its absorption or obstruction in CSF motion. In near history scientist interpret root cause of Normal pressure hydrocephalus based on the bulk mass motion of CSF from the ventricles. But, later on researches shown that the bulk flow theory of CSF can no longer explain the cause of Normal pressure hydrocephalus and researches narrow to focus on pulsatile dynamic behavior of intracranial system and dynamics behavior of CSF through the cerebral aqueduct.  Ventricular system of the brain can be basically divided in to four parts and cerebral aqueduct is the smallest part of ventricular system which acts as a linking passage between ventricles and subarachnoid space of the spinal cord.  Since cerebral aqueduct is the hub point of CSF distribution, it is easy to recognize any abnormalities of CSF formation and absorption by observing about the cerebral aqueduct. Development of mathematical model based on the behaviors of CSF motion through the cerebral aqueduct is the most reliable method. Magnetic Resonance Imaging can be used to examine the abnormalities in lateral ventricles and third ventricles by enlarging them. But, cerebral aqueduct was being less examined part because of its small dimensions. (MRI) and Computational Tomography (CT) observations are expensive and also due to the limited access of good health care system in third world country inhabitants. CSF flow across the cerebral aqueduct is influenced by the several factors. Though choroid plexus continuously generate cerebral spinal fluids, its pulsatile motion which is synchronized with the systole and diastole interprets a correlation between CSF driving force and cardiac cycle. In this comprehensive study, author paid attention to the correlation of cardiac cycle and CSF pulsatile motion to develop a math model which can described CSF driving force by considering the arterial wall expansion and contraction. In order to develop a mathematical model, number of parameters has been considered and MRI data was highly helpful. Subsequently, author has been able to successfully define the CSF driving force. Math-model has been analytically and computationally validated by comparing the results with actual clinical data. Developed math model was applied to predict the CSF velocity variation through the narrowest part of aqueduct in normal and normal pressure hydrocephalus patient. This has been done by CFD analysis, solid models which were used to analysis were developed by using MRI DICOM files of patients admitted to Thammasat hospital. Author has noticed that, maximum velocity of CSF exerts in the narrowest point of aqueduct. Quantitatively, maximum velocity of CSF of NPH patient was considerably higher than the maximum velocity of CSF of normal patient.After that, static pressure analysis for ventricular system has been done to examine the response of ventricular system with respect to the different intracranial pressure conditions correspond to different morphometric of aqueduct. Results implied were, for NPH patients, lateral ventricles tend to expand to regulate the pressure while normal patients regulates ICP by expanding the volume of aqueduct.Development of mathematical model to predict dynamic behavior of CSF through the cerebral aqueduct would be help to observe abnormalities of CSF motion and will help to identify hydrocephalus patients at their initial stage. Ultimately, this hypothesis might explore the understanding and direct the effective treatment procedure for the patient who suffers from disorder related to abnormalities of CSF motion.