In this Thesis we develop mathematical models to analyze two proposed causative mechanisms for the ventricular expansion observed in hydrocephalus: cerebrospinal fluid pulsations and small transmantle pressure gradients. To begin, we describe a single compartment model and show that such simple one-dimensional models cannot represent the complex dynamics of the brain. Hence, all subsequent models of this Thesis are spatio-temporal. Next, we develop a poroelastic model to analyze the fluid-solid interactions caused by the pulsations. Periodic boundary conditions are applied and the system is solved analytically for the tissue displacement, pore pressure, and fluid filtration. The model demonstrates that fluid oscillates across the brain boundaries. We develop a pore flow model to determine the shear induced on a cell by this fluid flow, and a comparison with data indicates that these shear forces are negligible. Thus, only the material stresses remain as a possible mechanism for tissue damage and ventricular expansion. In order to analyze the material stresses caused by the pulsations, we develop a fractional order viscoelastic model based on the linear Zener model. Boundary conditions appropriate for infants and adults are applied and the tissue displacement and stresses are solved analytically. A comparison of the tissue stresses to tension data indicates that these stresses are insufficient to cause tissue damage and thus ventricular expansion. Using age-dependent data, we then determine the fractional Zener model parameter values for infant and adult cerebra. The predictions for displacement and stresses are recomputed and the infant displacement is found to be unphysical. We propose a new infant boundary condition which reduces the tissue displacement to a physically reasonable value. The model stresses, however, are unchanged and thus the pulsation-induced stresses remain insufficient to cause tissue damage and ventricular expansion. Lastly, we develop a fractional hyper-viscoelastic model, based on the Kelvin- Voigt model, to obtain large deformation predictions. Using boundary conditions and parameter values for infants, we determine the finite deformation caused by a small pressure gradient by summing the small strain deformation resulting from pressure gradient increments. This iterative technique predicts that pediatric hydrocephalus may be caused by the long-term existence of small transmantle pressure gradients. We conclude the Thesis with a discussion of the results and their implications for hydrocephalus research as well as a discussion of future endeavors.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Göteborg : Göteborgs universitet , 2007. / Härtill 4 uppsatser.

Thesis (M.S.)--Brigham Young University. Dept. of Communication Disorders, 2007. / Includes bibliographical references (p. 44-51).

Normal pressure hydrocephalus (NPH) is characterised by a build-up of cerebrospinal fluid (CSF) in the brain despite apparently normal CSF pressure at lumbar puncture. In addition to movement and urinary symptoms, patients commonly display cognitive decline and apathy. NPH is recognised as an important cause of cognitive decline as it is thought be reversible with surgical CSF diversion (e.g. shunt surgery). However, this remains controversial and the neuropsychology of NPH is relatively poorly understood. Further, despite being the most commonly reported neuropsychiatric symptom in NPH, the significance of the symptom of apathy has not yet been elucidated. This thesis aims to expand on the neuropsychological and neuropsychiatric research in NPH, with the main objectives being to investigate neuropsychological outcome, and the significance of the symptom of apathy in NPH. In order to investigate neuropsychological outcome following shunt surgery in NPH, a systematic review and meta-analysis was conducted (Chapter 2). The findings from studies which used a battery of neuropsychological tests to assess cognitive outcome in NPH were combined. Meta-analyses were conducted on pre-operative and difference scores for the most commonly used neuropsychological tests. These were seven tests which spanned global cognitive function, learning and memory, executive function and psychomotor speed. Results for all tests were significant in the direction of improvement. However, the significance of the results for two measures of executive function were deemed not to be robust. This is discussed in line with previous research which suggests that executive function may be less likely to improve following shunt surgery than other neuropsychological domains. Next, the thesis focuses on the symptom of apathy. Chapter 3 investigated whether apathy in NPH relates to cognitive outcome and to a measure of ventricular enlargement. A reduction in apathetic symptoms following treatment was associated with better performance in a measure of global cognitive function. Further, larger ventricles (which may indicate greater disease severity/ brain damage) was associated with more severe apathy. A structural MRI study was then conducted to expand on these findings and to define brain structural correlates of apathy in NPH (Chapter 4). Results from this study suggested a potential role of the caudate nuclei in apathetic symptoms in NPH. Finally, consideration is given to the assessment of apathy in NPH. Since apathy is rarely investigated in patients with NPH it is unclear which assessment method is most appropriate for this patient group. Chapter 5 presents findings from a feasibility study of a novel reward learning task to determine whether it might be useful as an objective measure of motivation and apathy in NPH.

Brain cerebrospinal fluid (CSF) bulk flow is maintained thanks to a balance between CSF secretion from the choroid plexus and CSF absorption by arachnoid villi, where it drains into nearby blood vessels, thereby reaching the general blood circulation. Congenital hydrocephalus starts during the first trimester of pregnancy with impeded CSF flow, and consequent CSF build-up within the brain ventricles. This event is followed by CSF compositional changes, increased intracranial pressure, and, if untreated, brain damage and fetal death. Previous research has revealed a unique folate delivery system which serves the developing cerebral cortex. Abnormal folate provision due to impairment of this system was directly connected to a decrease in a CSF folate enzyme: 10-Formyl-Tetrahydrofolate dehydrogenase (FDH). In light of these findings, low FDH was linked with folate deficiency and the poor cortical development found in congenital hydrocephalus. In this context, investigations were carried out to ascertain whether folates in the presence and absence of the folate enzyme FDH are beneficial for fetal brain development. The current study also aims to investigate the FDH -folate delivery system in the fetal brain in order to understand its role in CNS development and its relationship to currently known folate transport mechanisms (FRα). Furthermore, we hypothesize that folates may prevent congenital hydrocephalus through a re-establishment of CSF drainage and flow circulation at the level of the arachnoid membrane/villi. This assumption implies that the leptomeninge arachnoid may also be dysfunctional in the hydrocephalic brain due to a variation in hydrocephalic CSF composition (folates). Finally, an overall metabolic pathway analysis of the constituents uniquely present in abnormal CSF, hence missing in normal CSF, and vice versa, was carried out to establish associations with suggested activated and inactivated biological processes during congenital hydrocephalus.

Indiana University-Purdue University Indianapolis (IUPUI) / Hydrocephalus is a disease characterized by an increase in cerebrospinal fluid (CSF) in the ventricles of the brain. This manifests as a result of either overproduction or underabsorption of CSF leading to increases in pressure, swelling and loss of brain matter. Current treatments for this disease include surgical interventions via the introduction of shunts or endoscopic third ventriculostomy, both of which aim to redirect flow of CSF in to another cavity for absorption. Limited pharmacotherapies are available in the treatment of hydrocephalus, and there exists a clinical need for drug therapies, which can ameliorate the pathophysiology associated with hydrocephalus and ventriculomegaly. CSF is produced primarily by the choroid plexus (CP), found in the ventricles of the brain. Composed of a high resistance epithelium surrounding a capillary network, the CP epithelium acts as a barrier, regulating ion transport between the CSF and blood. Transient Receptor Potential Vanilloid-4 (TRPV4) is a nonselective Ca2+-permeable cation channel expressed in the CP which is being investigated for its role in CSF production. To study hydrocephalus, we utilize two model systems; the TMEM67-/- Wpk rat, and the PCP-R cell line. The Wpk rat model is used to study the effects of drug intervention on the development and progression of hydrocephalus. The PCP-R cell line is utilized for studies which aim to understand the mechanisms by which CSF is produced. Using Ussing chamber electrophysiology, we are able to study the role of specific channels, transporters and modulators in driving epithelial ion flux across the CP. This research aims to establish a role for TRPV4 in production and regulation of CSF, and to interrogate a mechanism by which this ion transport occurs. The chapters that follow describe components of the pathway by which TRPV4 is activated and ion flux is stimulated.

No description available.

Wir untersuchten Liquor- und Serumproben von 40 an einem shuntversorgten Hydrocephalus erkrankten Kindern auf die Konzentration der Zytokine bFGF, TGF-β1, VEGF, IL-6, IGF-1 und Leptin sowie deren Korrelation mit dem Risiko von Shuntinsuffizienzen. Dabei konnten wir die Hypothese bestätigen, dass erhöhte Konzentration der fibrogenen Zytokine bFGF und TGF-β1 im Serum bzw. Liquor mit einem erhöhten Risiko für operationspflichtige Shuntinsuffizienzen durch Obstruktion des Schlauchsystems einhergehen, und dass diese Komplikationen mit steigenden Zytokinkonzentrationen umso eher eintreten. Außerdem war bFGF im Liquor von Kindern, die zum Abnahmezeitpunkt an einer Shuntdysfunktion durch Obstruktion oder Einwachsen des Shunts litten, signifikant höher als bei Kindern, die zum Zeitpunkt der Abnahme keine Shuntdysfunktion aus eben genannten Gründen hatten. Des Weiteren fanden wir Konzentrationsunterschiede für IL-6 im Liquor zwischen den einzelnen Ursachen der Erkrankung, wobei das Zytokin am höchsten bei Tumorpatienten war, gefolgt von posthämorrhagischem und postmeningitischem Hydrocephalus, und am niedrigsten bei Kindern mit kongenitaler ZNS-Fehlbildung.

Introduction: Temporary QT-interval prolongation following intracranial hemorrhage and hydrocephalus has been repeatedly reported in adults. Case: We report a case of excessive QT prolongation with sudden bradycardia resulting in 2:1 atrioventricular conduction in a preterm infant most likely associated with a congenital hydrocephalus. Pathomechanisms are discussed. Conclusion: Congenital hydrocephalus predisposes to excessive QT prolongation in preterm infants.