Thesis (Ph. D.)--Lund University, 1995. / Summary in Swedish. Contains reprints of 5 papers authored in part by the thesis author. eContent provider-neutral record in process. Description based on print version record.

Thesis (Ph. D.)--Lund University, 1995. / Summary in Swedish. Contains reprints of 5 papers authored in part by the thesis author.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

Following trauma, such as an impact injury or stroke, brain tissue can swell. Swelling is the result of water accumulation in the tissue that is driven by pathological changes, such as increased permeability of the capillary walls and osmotic pressure changes within the tissue. Swelling causes increased intracranial pressure and mechanical deformation of the brain tissue, exacerbating the original injury. Furthermore, prolonged local swelling can lead to the spread of damage to the (initially undamaged) surrounding tissue, since compression and increased intracranial pressure may restrict blood flow in this tissue. In this thesis, we develop mathematical models to examine the consequences of pathophysiological damage mechanisms on the swelling, and associated stress and strain, experienced by brain tissue. Mixture theory is used to represent brain tissue as a mixture of elastic solid, fluid and solutes. This modelling approach allows elastic deformations to be coupled with hydrodynamic pressure and osmotic gradients; the consequences of different mechanisms of damage may then be quantified. We consider three particular problems motivated by experimental observations of swelling brain tissue. Firstly, we investigate the swelling of isolated, damaged, brain tissue slices; we show that mechanisms leading to an osmotic pressure difference between the tissue slice and its surroundings can explain experimental observations for swollen tissue slices. Secondly, we use our modelling approach to demonstrate that local changes in capillary permeability can cause significant stresses and strains in the surrounding tissue. Thirdly, we investigate the conditions under which a locally swollen, damaged, region can cause compression of the vasculature within the surrounding tissue, and potentially result in damage propagation. To do this, we propose a coupled model for the oxygen concentration within, and mechanical deformation of, brain tissue. We use our model to assess the impact of treatment strategies on damage propagation through the tissue, and show that performing a craniectomy reduces the extent of propagation.

INTRODUÇÃO: O edema peritumoral (EP) está presente em aproximadamente 60% dos meningiomas. Os fatores responsáveis pela formação do edema e sua importância clínica permanecem como foco de discussão. OBJETIVOS: Analisar a correlação entre a presença de edema com características clínicas, cirúrgicas, radiológicas e recorrência tumoral. MÉTODOS: Foram selecionados 61 pacientes portadores de meningiomas benignos submetidos a tratamento cirúrgico pelo Grupo de Tumores Encefálicos e Metástases do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Foram incluídos no estudo os portadores de meningiomas benignos submetidos a ressecção tumoral completa (Simpson 1 e 2). Foram excluídos pacientes portadores de meningiomas malignos ou atípicos e aqueles localizados em tubérculo selar, seio cavernoso, forame magno, intraventriculares e região petroclival. RESULTADOS: Encontramos correlação entre as maiores medidas de edema peritumoral e recorrência tumoral (p = 0,042) e tumores com margens irregulares (p < 0,011) na análise bivariada. Além disso, os pacientes que apresentaram maiores volumes tumorais apresentaram maiores medidas de edema (p = 0,035) e nos pacientes com menores medidas de edema a localização tentorial foi mais freqüente (p = 0,032). Verificamos que ao estudo de regressão logística, o EP apresenta correlação com tumores maiores que 40 cm3 (Odds ratio=15,977), crises convulsivas (Odds ratio=3,469) e para cada cm3 acrescida ao tamanho tumoral o risco de edema cresce 1,082 vez (Odds ratio). CONCLUSÕES: Considerando os resultados obtidos, o EP esteve associado a maior recorrência tumoral, tumores multilobulados, grandes e a presença de crises convulsivas. A localização tentorial mostrou-se como um fator protetor ao EP. O EP pode estar associado a um potencial invasivo aumentado em meningiomas. Desta forma, o seu estudo aprofundado poderá trazer dados adicionais para o esclarecimento dos mecanismos de formação dos meningiomas e de seu comportamento biológico levando ao melhor manejo clínico dos pacientes. / INTRODUCTION: Approximately 60% of meningiomas are associated with peritumoral edema.Various causative factors have been discussed in the literature. PURPOSES: Investigate the correlation of peritumoral edema with clinical, radiological and surgical aspects, and recurrence rate of meningiomas. METHODS: Sixty one benign meningiomas submitted to surgical treatment by the Group of Brain Tumors and Metastasis of the Division of Neurosurgery of the Hospital das Clínicas of São Paulo Medical School of São Paulo University. All patients underwent complete surgical ressection (Simpson 1 and 2) and were excluded the atypical and malignant hystopathological grades. The tumors located in the cavernous sinus, tuberculum sellae region, foramen magnum region, ventricular space and petroclival region were excluded. RESULTS: Edema extention had a positive correlation with the higher recurrence rates (p = 0,042) and with the presence of irregular margins (p < 0,011) on bivariate analysis. Meningiomas with greater edema sizes also showed correlation with large meningiomas (p = 0,035) and the ones with smaller edema sizes correlated with the tentorial location (p=0,032). Multivariate analysis showed an association between peritumoral brain edema and the presence of seizures (Odds ratio=3,469), large meningiomas (Odds ratio=15,977), and for each cubic centimeter added to its size, the risk of edema increased 1,082 times (Odds ratio). CONCLUSION: Peritumoral brain edema correlated with recurrence, irregular margins, seizures and larger tumors. The tentorial location demonstrated smaller edema sizes. Peritumoral brain edema may be related to meningioma\'s invading potentiality and may play a role in the recurrence pontential of the tumor. As a consequence, it\'s reasonable to consider edema\'s presence as an additional factor to be taken into account when arranging layout of strategies for meningiomas treatment.

INTRODUÇÃO: O edema peritumoral (EP) está presente em aproximadamente 60% dos meningiomas. Os fatores responsáveis pela formação do edema e sua importância clínica permanecem como foco de discussão. OBJETIVOS: Analisar a correlação entre a presença de edema com características clínicas, cirúrgicas, radiológicas e recorrência tumoral. MÉTODOS: Foram selecionados 61 pacientes portadores de meningiomas benignos submetidos a tratamento cirúrgico pelo Grupo de Tumores Encefálicos e Metástases do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Foram incluídos no estudo os portadores de meningiomas benignos submetidos a ressecção tumoral completa (Simpson 1 e 2). Foram excluídos pacientes portadores de meningiomas malignos ou atípicos e aqueles localizados em tubérculo selar, seio cavernoso, forame magno, intraventriculares e região petroclival. RESULTADOS: Encontramos correlação entre as maiores medidas de edema peritumoral e recorrência tumoral (p = 0,042) e tumores com margens irregulares (p < 0,011) na análise bivariada. Além disso, os pacientes que apresentaram maiores volumes tumorais apresentaram maiores medidas de edema (p = 0,035) e nos pacientes com menores medidas de edema a localização tentorial foi mais freqüente (p = 0,032). Verificamos que ao estudo de regressão logística, o EP apresenta correlação com tumores maiores que 40 cm3 (Odds ratio=15,977), crises convulsivas (Odds ratio=3,469) e para cada cm3 acrescida ao tamanho tumoral o risco de edema cresce 1,082 vez (Odds ratio). CONCLUSÕES: Considerando os resultados obtidos, o EP esteve associado a maior recorrência tumoral, tumores multilobulados, grandes e a presença de crises convulsivas. A localização tentorial mostrou-se como um fator protetor ao EP. O EP pode estar associado a um potencial invasivo aumentado em meningiomas. Desta forma, o seu estudo aprofundado poderá trazer dados adicionais para o esclarecimento dos mecanismos de formação dos meningiomas e de seu comportamento biológico levando ao melhor manejo clínico dos pacientes. / INTRODUCTION: Approximately 60% of meningiomas are associated with peritumoral edema.Various causative factors have been discussed in the literature. PURPOSES: Investigate the correlation of peritumoral edema with clinical, radiological and surgical aspects, and recurrence rate of meningiomas. METHODS: Sixty one benign meningiomas submitted to surgical treatment by the Group of Brain Tumors and Metastasis of the Division of Neurosurgery of the Hospital das Clínicas of São Paulo Medical School of São Paulo University. All patients underwent complete surgical ressection (Simpson 1 and 2) and were excluded the atypical and malignant hystopathological grades. The tumors located in the cavernous sinus, tuberculum sellae region, foramen magnum region, ventricular space and petroclival region were excluded. RESULTS: Edema extention had a positive correlation with the higher recurrence rates (p = 0,042) and with the presence of irregular margins (p < 0,011) on bivariate analysis. Meningiomas with greater edema sizes also showed correlation with large meningiomas (p = 0,035) and the ones with smaller edema sizes correlated with the tentorial location (p=0,032). Multivariate analysis showed an association between peritumoral brain edema and the presence of seizures (Odds ratio=3,469), large meningiomas (Odds ratio=15,977), and for each cubic centimeter added to its size, the risk of edema increased 1,082 times (Odds ratio). CONCLUSION: Peritumoral brain edema correlated with recurrence, irregular margins, seizures and larger tumors. The tentorial location demonstrated smaller edema sizes. Peritumoral brain edema may be related to meningioma\'s invading potentiality and may play a role in the recurrence pontential of the tumor. As a consequence, it\'s reasonable to consider edema\'s presence as an additional factor to be taken into account when arranging layout of strategies for meningiomas treatment.

No description available.

Traumatic brain injury (TBI) has a 20% mortality rate and a 10-15% rate of resultant permanent disability. The consequences of TBI range from brief loss of consciousness, to prolonged coma or death. Mild TBI is amongst the common causes of admission to trauma centers all over the world. Future technologies such as magnetic resonance elastography and robotic surgery demand information about the physical properties of brain tissue. Walsh and Schettini described the mechanical behavior of brain tissue under normal status as nonlinear viscoelastic behavior and defined the associated biomechanical changes and responses in a quantitative measurement of the material changes. Yet, there is still a lack of data concerning time-dependent deformation and mechanical property changes associated with TBI. My goal in this project was to describe these mechanical responses and to create a system for measuring and evaluating the mechanical response of brain tissue in vivo. This was to be achieved by inducing cortical contusions with a calibrated weight-drop method in seventy-four young adult male Sprague-Dawley rats. Instrumented indentation was performed on control brains and 1 hour to 3 weeks after contusion with intact dura using a 4-mm-diameter flat punch indenter to a maximum depth of 1.2 mm at loading. Loading rates did not exceed 0.34 N/min and 1.2 mm/min. In order to obtain force displacement data, we studied the elastic response of the traumatized brain tissue and the deformation process (creep) during the loading and unloading of indenter. After euthanasia, the brain was removed and evaluated histologically with different methods to reveal acute and chronic changes related to the contusion. The results revealed that the biomechanical properties of the brain tissue were changed after cortical contusion. Brain tissue elasticity decreased in the edematous brain at one day following the contusion and increased at 3 weeks, in association with reactive astroglial changes. This experimental technique, combined with mathematical modeling, might eventually lead to a better understanding of the physical changes in brain following TBI.