Computer simulation of syringomyelia in dogs

Syringomyelia is a pathological condition in which fluid-filled cavities (syringes) form and expand in the spinal cord. Syringomyelia is often linked with obstruction of the craniocervical junction and a Chiari malformation, which is similar in both humans and animals. Some brachycephalic toy breed dogs such as Cavalier King Charles Spaniels (CKCS) are particularly predisposed. The exact mechanism of the formation of syringomyelia is undetermined and consequently with the lack of clinical explanation, engineers and mathematicians have resorted to computer models to identify possible physical mechanisms that can lead to syringes. We developed a computer model of the spinal cavity of a CKCS suffering from a large syrinx. The model was excited at the cranial end to simulate the movement of the cerebrospinal fluid (CSF) and the spinal cord due to the shift of blood volume in the cranium related to the cardiac cycle. To simulate the normal condition, the movement was prescribed to the CSF. To simulate the pathological condition, the movement of CSF was blocked

New Mechanics of Traumatic Brain Injury

The prediction and prevention of traumatic brain injury is a very important aspect of preventive medical science. This paper proposes a new coupled loading-rate hypothesis for the traumatic brain injury (TBI), which states that the main cause of the TBI is an external Euclidean jolt, or SE(3)-jolt, an impulsive loading that strikes the head in several coupled degrees-of-freedom simultaneously. To show this, based on the previously defined covariant force law, we formulate the coupled Newton-Euler dynamics of brain's micro-motions within the cerebrospinal fluid and derive from it the coupled SE(3)-jolt dynamics. The SE(3)-jolt is a cause of the TBI in two forms of brain's rapid discontinuous deformations: translational dislocations and rotational disclinations. Brain's dislocations and disclinations, caused by the SE(3)-jolt, are described using the Cosserat multipolar viscoelastic continuum brain model. Keywords: Traumatic brain injuries, coupled loading-rate hypothesis, Euclidean jolt, coupled Newton-Euler dynamics, brain's dislocations and disclinationsComment: 18 pages, 1 figure, Late

Caracterización matemática de factores implicados en la aparición de la siringomielia en condiciones de ingravidez

Este proyecto de fin de grado tiene como objetivo caracterizar el flujo y comportamiento del líquido cefalorraquídeo (CSF) bajo la influencia de la gravedad. Simulamos condiciones normales y de ingravidez para comparar y analizar los resultados. Material y métodos: Para este proyecto de investigación, se utilizaron imágenes de resonancia magnética (MRI) para crear un modelo 3D que representara el espacio del líquido cefalorraquídeo (CSF), el propio líquido y la médula espinal para su posterior análisis mediante los programas Ansys Fluent, Structural Transient y Matlab. Para la segmentación de imágenes, se utilizó el programa 3D Slicer, mientras que para mejorar el modelo se utilizaron MeshLab y Spaceclaim. En cuanto al análisis, se utilizó Ansys Fluent para el estudio del flujo del CSF, Structural Transient para el estudio de la deformación de la médula espinal, y Matlab para el procesamiento de datos y la obtención de resultados numéricos. Resultados: La distribución de presión a lo largo de la médula espinal mostró un cambio gradual de una presión alta a una presión baja, mientras que la duramadre presentó una distribución de presión relativamente constante. El modelo que simulaba la siringomielia mostró una interrupción en el flujo del líquido cefalorraquídeo (LCR), caracterizada por obstrucción y cambios en las trayectorias, reflejando la anatomía realista de la médula espinal. Además, el modelo que simulaba la siringomielia exhibió una deformación visual más pronunciada, con un notable aumento de tamaño y una mayor tensión en la parte inferior. El análisis del caudal reveló variaciones cíclicas en los flujos de entrada y salida, reflejando el equilibrio dinámico del transporte del LCR Conclusiones: Nuestro estudio ha contribuido a una mejor comprensión de las complejas interacciones biomecánicas entre la médula espinal y el líquido cefalorraquídeo (LCR). Hemos obtenido datos significativos..

A CFD and FEM Approach to a Multicompartmental Poroelastic Model for CSF Production and Circulation with Applicationsin Hydrocephalus Treatment and Cerebral Oedema

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.This study introduces a Multiple-Network Poroelastic Theory (MPET) model, coupled with finite-volume based Computational fluid dynamics (CFD) for the purpose of studying, in detail, the effects of obstructing Cerebrospinal fluid (CSF) transport within an image-derived cerebral environment. The MPET representation allows the investigation of fluid transport between CSF, brain parenchyma and cerebral blood, in an integral and comprehensive manner. Key novelties of this model are the casting of multidimensional MPET in a Finite Element Method (FEM) framework, the amalgamation of anatomically accurate choroid plexuses with their feeding arteries and a simple relationship relaxing the constraint of a unique permeability for the CSF compartment. This model is used to demonstrate the impact of fourth ventricle outlet obstruction (FVOO). The implications of treating such a clinical condition with the aid of endoscopic third (ETV) and endoscopic fourth (EFV) ventriculostomy are considered. Finally, we outline the impact of the FEM based MPET framework in understanding oedema, and its ongoing evolution

Syringomyelia: A review of the biomechanics

Syringomyelia is a neurological disorder caused by the development of one or more macroscopic fluid-filled cavities in the spinal cord. While the aetiology remains uncertain, hydrodynamics appear to play a role. This has led to the involvement of engineers, who have modelled the system in silico and on the bench. In the process, hypotheses from the neurosurgical literature have been tested, and others generated, while aspects of the system mechanics have been clarified. The spinal cord is surrounded by cerebrospinal fluid (CSF) which is subject both to the periodic excitation of CSF expelled from the head with each heartbeat, and to intermittent larger transients from cough, sneeze, etc., via vertebral veins. The resulting pulsatile flow and pressure wave propagation, and their possible effects on cord cavities and cord stresses, have been elucidated. These engineering contributions are here reviewed for the first time

Multicompartmental poroelastic modelling for CSF production and circulation

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.This study proposes the implementation of a Multiple-Network Poroelastic Theory (MPET) model for the purpose of investigating in detail the transport of water within the cerebral environment. The advantage of using the MPET representation is that it accounts for fluid transport between CSF, brain parenchyma and cerebral blood. They key novelty in the model discussed in the present study is the amalgamation of anatomically accurate Choroid Plexus regions, with their individual feeding arteries. This model is used to demonstrate the impact of aqueductal stenosis and atresia of the Foramina of Luschka and Magendie on the cerebral ventricles. The possible implications of treating such a condition with the aid of endoscopic third ventriculostomy are investigated and discussed.This study is supported by the Research Councils UK cross council initiative led by EPSRC and contributed to by AHRC, ESRC, and MRC

Mathematical model of the cerebral circulation and distribution of cerebrospinal fluid

Shifts in cerebral fluid are known to be important in a number of diseases, and in conditions of microgravity such as space travel. In this work we develop a fluid mechanical model from firstprinciples incorporating key features of the flow of both blood and cerebrospinal fluid (CSF) in the intracranial and spinal spaces. For the cerebral blood vessels, we model the arteries and veins as symmetric bifurcating trees with constant geometrical scaling factors between generations, assume one-dimensional flow in each vessel and account for elastic effects via a pressure-area relationship, and we assume the capillaries have a constant resistance. We treat the vessel walls as porous media to find the transmural flux of plasma. We assume flow between the other compartments to be proportional to the pressure difference; additionally, the flow to the outer-dural space is assumed to be one-way. The set of ordinary differential equations for the evolution of the fluid pressures and volumes of each compartment can be solved numerically. Additional features include autoregulation, which we model by ensuring constant pressure at the microcirculation, meaning the resulting model must be solved iteratively. Also, we can model the effect of postural changes by including hydrostatic effects in the spinal column. The results are in accordance with physiological measurements and indicate that the pressure in the vasculature is highly sensitive to changes in vessel geometry, which also affects the transmural flux, whilst ventricular and spinal subarachnoid spaces are sensitive to compliances. We investigate transitions from supine to standing and upside down positions and also the effect of the external pressure surrounding the outer-dural spinal compartment. The model is computationally inexpensive and can be used as a platform for further analysis of cerebrovascular behaviour.Open Acces