Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Nitrous oxide (N2O) is inhaled in anesthesia and as a recreational drug from whipped cream dispensers. Its abuse reaches approximately 10% in some age groups. By inactivating cobalamin (Cbl) (vitamin B12), N2O can cause neurologic and hematologic manifestations. We present a case of N2O-induced Cbl deficiency presenting as cervical myelopathy. ⋯ This patient presented with the symptoms and signs of Cbl deficiency. The MRI lesions in the posterior columns aided the diagnosis. Physicians need to have a high level of suspicion in cases of unexplained Cbl deficiency and myelopathy.
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The thrombolysis in myocardial infarction (TIMI) grading scheme and other classification systems have limitations in evaluating patients with ischemic stroke because they do not account for occlusion location or collateral circulation. The Qureshi grading scheme has been recently proposed to evaluate the severity of arterial occlusion in acute ischemic stroke because of limitations in existing grading systems. ⋯ The Qureshi grading scheme can be effectively used to determine the severity of ischemic stroke (brain at risk) from the initial angiography.
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For more than a century, multiple sclerosis was viewed as a disease process characterized by oligodendrocyte and myelin loss, and research into the pathogenesis of multiple sclerosis was mainly focused on the mechanisms of inflammation. However, with development of more sophisticated neuroimaging and molecular biology techniques, attention has shifted to new aspects of pathogenesis of multiple sclerosis: axonal loss and neurodegeneration. Evidence is increasing that tissue destruction, primarily axonal loss and neurodegeneration, is a key element in the pathogenesis of multiple sclerosis. ⋯ However, these repair mechanisms eventually fail, and patients typically develop generalized brain atrophy, cognitive decline, and permanent disability. Although the exact mechanisms underlying central nervous system atrophy in patients with multiple sclerosis are largely unknown, evidence exists that atrophy may represent an epiphenomenon related to the effects of dynamic inflammation within the central nervous system, including demyelination, axonal injury, neuronal loss, Wallerian degeneration, and possibly iron deposition. This article summarizes the potential mechanisms involved in central nervous system atrophy in patients with multiple sclerosis.
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Transcranial color-coded duplex sonography (TCCS), in contrast to "blind" conventional transcranial Doppler sonography (TCD), enables a sonographer to outline the intracranial bony and parenchymal structures, visualize the basal cerebral arteries in color, and measure angle-corrected blood flow velocities in a specific site of the artery in question. This makes measurements of flow velocity more valid than those obtained with conventional TCD. TCCS is becoming a reliable tool for detecting the occlusion and narrowing of major intracranial arterial trunks. ⋯ Large and medium-sized arteriovenous malformations can also be detected with TCCS. The rapid sonographic assessment of cerebral hemodynamics in a neurosurgical patient with increased intracranial pressure can guide further management. The use of sonographic contrast agents can increase the number of conclusive TCCS studies in patients with insufficient acoustic windows.
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In multiple sclerosis (MS), the spinal cord is a common area of involvement, and its dysfunction is likely to be responsible for much of motor disability. It has been reported that atrophy in the cervical spinal cord occurs early and is detectable in patients presenting with a clinically isolated syndrome. ⋯ This review summarizes the underlying pathology responsible for spinal cord atrophy and the methods available to measure it. The relationships between spinal cord atrophy, other magnetic resonance imaging parameters, and clinical disability are also discussed.