Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · Aug 2015
ReviewImaging of Orbital Trauma and Emergent Non-traumatic Conditions.
Diagnostic imaging has become critical in the care of patients suffering from traumatic or nontraumatic emergent orbital conditions. Multidetector computed tomography (MDCT) has become the standard imaging modality for assessing orbital trauma because of its accurate assessment of orbital skeletal and soft tissues injuries. ⋯ Conventional angiography is necessary in some vascular orbital complications and allows for endovascular treatment. This article discusses the spectrum of orbital pathology encountered in the imaging of orbital trauma and nontraumatic orbital emergencies.
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Neuroimaging Clin. N. Am. · Aug 2015
ReviewImaging of Retrochiasmal and Higher Cortical Visual Disorders.
Retrochiasmal visual pathways include optic tracts, lateral geniculate nuclei, optic radiations, and striate cortex (V1). Homonymous hemianopsia and field defect variants with relatively normal visual acuity suggest that the lesions involve retrochiasmal pathways. From V1, visual input is projected to higher visual association areas that are responsible for perception of objects, faces, colors, and orientation. ⋯ Damage to the ventral stream results in visual object agnosia, prosopagnosia, and achromatopsia. Balint syndrome, visual inattention, and pure alexia are examples of dorsal stream disorders. Posterior cortical atrophy can involve ventral and dorsal streams, often preceding dementia.
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Eye movement is controlled by ocular motor pathways that encompass supranuclear, nuclear, and infranuclear levels. Lesions affecting certain locations may produce localizing signs that help radiologists focus on specific anatomic regions. ⋯ Some conditions are life threatening and require urgent or emergent imaging. MR imaging is the imaging of choice in evaluation of ocular motor palsy, with magnetic resonance angiography or computed tomography angiography indicated in cases of suspected aneurysms or neurovascular conflicts.