RESUMEN
With the advent of real-time MRI, the motion and passage of cerebrospinal fluid can be visualized without gating and exclusion of low-frequency waves. This imaging modality gives insights into low-volume, rapidly oscillating cardiac-driven movement as well as sustained, high-volume, slowly oscillating inspiration-driven movement. Inspiration means a spontaneous or artificial increase in the intrathoracic dimensions independent of body position. Alterations in thoracic diameter enable the thoracic and spinal epidural venous compartments to be emptied and filled, producing an upward surge of cerebrospinal fluid inside the spine during inspiration; this surge counterbalances the downward pooling of venous blood toward the heart. Real-time MRI, as a macroscale in vivo observation method, could expand our knowledge of neurofluid dynamics, including how astrocytic fluid preloading is adjusted and how brain buoyancy and turgor are maintained in different postures and zero gravity. Along with these macroscale findings, new microscale insights into aquaporin-mediated fluid transfer, its sensing by cilia, and its tuning by nitric oxide will be reviewed. By incorporating clinical knowledge spanning several disciplines, certain disorders-congenital hydrocephalus with Chiari malformation, idiopathic intracranial hypertension, and adult idiopathic hydrocephalus-are interpreted and reviewed according to current concepts, from the basics of the interrelated systems to their pathology.
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Cilios , Hidrocefalia , Adulto , Encéfalo , Líquido Cefalorraquídeo , Humanos , Imagen por Resonancia Magnética/métodosRESUMEN
New experimental and clinical findings question the historic view of hydrocephalus and its 100-year-old classification. In particular, real-time magnetic resonance imaging (MRI) evaluation of cerebrospinal fluid (CSF) flow and detailed insights into brain water regulation on the molecular scale indicate the existence of at least three main mechanisms that determine the dynamics of neurofluids: (1) inspiration is a major driving force; (2) adequate filling of brain ventricles by balanced CSF upsurge is sensed by cilia; and (3) the perivascular glial network connects the ependymal surface to the pericapillary Virchow-Robin spaces. Hitherto, these aspects have not been considered a common physiologic framework, improving knowledge and therapy for severe disorders of normal-pressure and posthemorrhagic hydrocephalus, spontaneous intracranial hypotension, and spaceflight disease.
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Hidrocefalia , Imagen por Resonancia Magnética , Anciano de 80 o más Años , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Ventrículos Cerebrales/diagnóstico por imagen , Ventrículos Cerebrales/fisiología , Humanos , Hidrocefalia/diagnóstico por imagen , Hidrocefalia/etiología , Imagen por Resonancia Magnética/métodosRESUMEN
PURPOSE: The specific pathophysiological processes in many forms of obstructive hydrocephalus (HC) are still unclear. Current concepts of cerebrospinal fluid (CSF) dynamics presume a constant downward flow from the lateral ventricles towards subarachnoid spaces, which are in contrast to neurosurgical observations and findings of MRI flow studies. The aim of our study was to analyze CSF movements in patients with obstructive HC by neuroendoscopic video recordings, X-ray studies, and MRI. METHODS: One hundred seventeen pediatric patients with obstructive HC who underwent neuroendoscopy in our center were included. Video recordings were analyzed in 85 patients. Contrast-enhanced X-rays were conducted during surgery prior to intervention in 75 patients, and flow void signals on pre-operative MRI could be evaluated in 110 patients. RESULTS: In 83.5% of the video recordings, CSF moved upwards synchronous to inspiration superimposed by cardiac pulsation. Application of contrast medium revealed a flow delay in 52% of the X-ray studies prior to neurosurgery, indicating hindered CSF circulation. The appearances and shapes of flow void signals in 88.2% of the pre-operative MRI studies suggested valve-like mechanisms and entrapment of CSF. CONCLUSIONS: Neuroendoscopic observations in patients with obstructive HC revealed upward CSF movements and the corresponding MRI signs of trapped CSF in brain cavities. These observations are in contrast to the current pathophysiological concept of obstructive HC. However, recent real-time flow MRI studies demonstrated upward movement of CSF, hence support our clinical findings. The knowledge of cranial-directed CSF flow expands our understanding of pathophysiological mechanisms in HC and is the key to effective treatment.
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Hidrocefalia/líquido cefalorraquídeo , Hidrocefalia/diagnóstico por imagen , Monitorización Neurofisiológica Intraoperatoria/métodos , Neuroendoscopía/métodos , Adolescente , Líquido Cefalorraquídeo/fisiología , Niño , Preescolar , Femenino , Humanos , Hidrocefalia/cirugía , Lactante , Imagen por Resonancia Magnética/métodos , Masculino , Estudios Prospectivos , Estudios Retrospectivos , Cirugía Asistida por Video/métodosRESUMEN
INTRODUCTION: Malignant brain tumors tend to migration and invasion of surrounding brain tissue. Histopathological studies reported malignant cells in macroscopically unsuspicious parenchyma (normal appearing white matter - NAWM) remote from the tumor localization. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is hypothesized. MATERIAL AND METHODS: Patients' ADC and FA values from NAWM of the hemisphere contralateral to a malignant glioma were compared to age- and sex-matched normal controls. RESULTS: Apparent diffusion coefficient levels of the entire contralateral hemisphere revealed a significant increase and a decrease of FA levels. An even more pronounced ADC increase was found in a region mirroring the glioma location. CONCLUSIONS: In patients with previously untreated anaplastic astrocytoma or glioblastoma, an increase of the ADC and a reduction of FA were found in the brain parenchyma of the hemisphere contralateral to the tumor localization. In the absence of visible MRI abnormalities, this may be an early indicator of microstructural changes of the NAWM attributed to malignant brain tumor.
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Astrocitoma/patología , Neoplasias Encefálicas/patología , Glioblastoma/patología , Sustancia Blanca/patología , Adulto , Anciano , Imagen de Difusión Tensora , Femenino , Lateralidad Funcional , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Information on structural chromosomal changes in brain metastases (BM) of colorectal carcinoma (CRC) is very limited. Therapeutic and diagnostic strategies to reduce the risk of BM have potential impact on cancer mortality. By using comparative genomic hybridization, the primary CRC of 11 patients and their corresponding 13 BM were analyzed. BM showed significantly more mean chromosomal aberrations than the primary CRC (13.6+/-2.1 vs. 7.9+/-1.9, P=0.03), significantly more chromosomal gains (7.2+/-0.9 vs. 3.5+/-0.9, P=0.01), and tended to have also more losses (6.1+/-1.4 vs. 4.0+/-1.1, P=0.29). Changes that occurred significantly more often in BM than in primary CRC were gains of 8q, 12p, 12q, and 20p, as well as losses of 5q. BM of CRC show a significantly higher chromosomal instability in comparison to primary tumors. The prevalently altered genomic regions in the metastases of this study are likely to harbor genes that play an important role in the genesis of brain-specific metastasis.
Asunto(s)
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/secundario , Carcinoma/genética , Carcinoma/secundario , Neoplasias Colorrectales/patología , Adulto , Anciano , Inestabilidad Cromosómica , Aberraciones Cromosómicas , Neoplasias Colorrectales/genética , Hibridación Genómica Comparativa , Humanos , Masculino , Persona de Mediana EdadRESUMEN
PURPOSE: To use localized in vivo proton magnetic resonance (MR) spectroscopy of the contralateral hemisphere in patients with glioblastoma multiforme (GBM) to detect alterations in cerebral metabolites as potential markers of infiltrating GBM cells. MATERIALS AND METHODS: The study was approved by the ethics committee, and written informed consent was obtained. Twenty-two patients with newly diagnosed and untreated GBM underwent in vivo single-voxel short echo time proton MR spectroscopy with a 3-T MR imaging system. Absolute metabolite concentrations in the hemisphere contralateral to the tumor were compared with data from five patients with low-grade gliomas (LGGs) and from a group of 14 age-matched control subjects by using analysis of variance and subsequent t tests or corresponding nonparametric tests. RESULTS: In the contralateral hemisphere, MR spectroscopy revealed increased concentrations of myo-inositol and glutamine. Mean myo-inositol levels were significantly increased in patients with GBM (3.6 mmol/L +/- 0.8 [standard deviation]) relative to levels in control subjects (3.1 mmol/L +/- 0.6; P = .03) and tended to be higher relative to levels in patients with LGG (2.7 mmol/L +/- 0.8; P = .09). Mean glutamine concentrations in patients with GBM (3.4 mmol/L +/- 0.9) differed significantly from those in control subjects (2.7 mmol/L +/- 0.7; P = .01); mean concentrations in patients with GBM differed from those in patients with LGG (2.4 mmol/L +/- 0.5; P = .01). There were no significant differences between data in patients with LGG and in control subjects. CONCLUSION: Increased concentrations of myo-inositol and glutamine in the contralateral normal-appearing white matter of GBM patients are consistent with mild astrocytosis and suggest the detectability of early neoplastic infiltration by using proton MR spectroscopy in vivo.