Posterior reversible encephalopathy syndrome is a remarkably heterogeneous group of disorders, related to hypertensive encephalopathy, severe preeclampsia/eclampsia, immunosuppressive drug or interferon neurotoxicity, uremia and thrombotic thrombocytopenic purpura . The clinical symptoms are headache, altered mental status, seizures and visual loss. Posterior reversible encephalopathy syndrome is due to dysfunction of a cerebrovascular autoregulatory system, and a vasculopathy of small vessels, the arterioles. Brain perfusion is maintained by the autoregulatory system of the small arteries and arterioles that have myogenic and neurogenic components. Since the vertebrobasilar system and posterior cerebral arteries are sparsely innervated by sympathetic nerves, the occipital lobes and other posterior brain regions are susceptible to a breakthrough of the autoregulation in case of a sudden elevation of the systemic blood pressure. Endothelial damage, which can attenuate the myogenic response of the autoregulatory system, is hypothesized to be the cause of the posterior reversible encephalopathy syndrome.
Other names for the posterior reversible en-cephalopathy syndrome are reversible posterior leukoencephalopathy syndrome, or posterior leuko-encephalopathy syndrome [34,35]. The lesion can also involve the cerebral cortex and another name for posterior reversible encephalopathy syndrome is occipital parietal encephalopathy . Similar lesions can also be seen in the frontal lobes, basal ganglia, brain stem
Probable Moyamoya disease in a 7-year-old girl with left hemipare-sis. a T2-weighted image shows mild high signal lesions in the right basal ganglia and parieto-occipital cortex. b DW image clearly shows these lesions as high signal intensity, representing acute infarcts. c MR angiography shows occlusion of the right middle cerebral artery and stenosis of the right internal carotid artery and bilateral posterior cerebral arteries (arrows).
and cerebellum. In addition, the posterior reversible encephalopathy syndrome may not be entirely reversible, as infarction and hemorrhage may develop.
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