Neuroimaging clinics of North America
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Infections of the spine represent a rare but potentially debilitating and neurologically devastating condition for patients. Early diagnosis, imaging, and intervention may prevent some of the more critical complications that may ensue from this disease process, including alignment abnormalities, central canal compromise, nerve root impingement, vascular complications, and spinal cord injury. This article reviews the underlying pathophysiologic basis of infection, clinical manifestations, and imaging modalities used to diagnose infections of the spine and spinal cord.
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Central nervous system infections account for 1% of primary hospital admissions and 2% of nosocomial infections and when encountered require prompt diagnosis and initiation of specific treatment. Imaging findings are mostly nonspecific with respect to the causative pathogen. This article describes the anatomy of cranial meninges and extra-axial spaces of the brain. Characteristic findings and recent advances in neuroimaging of meningitis and its complications and ventriculitis are summarized, and certain noninfectious causes of meningitis and meningitis mimics are described.
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Radiology provides valuable gross pathologic information about central nervous system (CNS) infections. Major categories of infectious lesions of the brain and spinal cord are recognized by imaging such as diffuse, focal, or multifocal. ⋯ It illustrates examples with gross and microscopic photographs of CNS infections, and the tissue reactions to these infections. Where the organism can spread within the CNS, and cellular responses to the organism underlie both the radiographic and pathologic findings.
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Neurocysticercosis (NCC) is an infection of the central nervous system by the Taenia solium larvae, and is the most common cause of acquired epilepsy in endemic regions. The natural history of parenchymal NCC lesions can be divided into 4 stages with unique imaging and clinical features. Evaluation of cysticerci is challenging on conventional magnetic resonance (MR) imaging and computed tomography, and is significantly improved with MR cysternography techniques. Differentiation of NCC lesions from metastatic disease and pyogenic abscesses can be improved with advanced MR imaging including (1)H nuclear MR spectroscopy, diffusion-weighted imaging, and MR perfusion imaging.
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Fungal infections of the central nervous system (CNS) frequently occur in the immunocompromised or debilitated host. Imaging findings are non-specific but may be organized into extra-axial, parenchymal, and vascular categories. Furthermore, knowledge of fungal morphology may predict the imaging manifestations with large, hyphal species having a predilection for brain parenchymal involvement, while small, unicellular organisms typically result in meningitis. Advanced imaging techniques such as diffusion-weighted imaging, MR perfusion and MR spectroscopy, when combined with clinical findings, may help in differentiating fungal disease from other mimckers such as pyogenic infection or cystic metastases.