Wednesday, July 17, 2013


Posterior reversible encephalopathy syndrome (PRES) is a clinic-neuroradiological syndrome associated with various clinical conditions, presenting with headache, encephalopathy, seizures,
cortical visual disturbances or blindness. Imaging predominantly shows parieto-occipital white matter changes, with vasogenic edema being the most accepted pathophysiology.
Common clinical conditions include hypertensive encephalopathy, renal failure, autoimmune disorders and treatment with immunosuppressant or cytotoxic medications.
Uncommon clinical conditions include acute intermittent porphyria and cryoglobulinemia.

Some of the earlier cases of PRES were seen with SLE patients and in kidney transplant patients the classic association is with CNIs in rare circumstances. Preeclampsia and eclampsia may be the most common  causes of PRES during pregnancy and most cases are managed without neuroimaging, and the incidence remains unknown.  However, it is uncertain whether a cause and effect relationship truly exists between the two or if these represent independent processes with some element of clinical overlap.
By definition, all patients with posterior reversible encephalopathy syndrome have a characteristic MRI pattern with bilateral hemispheric boundary zones of hyperintensities on T2 and FLAIR imaging, with increased apparent diffusion coefficient values, affecting the cortex and subcortical and deep white matter to varying degrees. The pathogenesis of PRES remains unclear, but it appears to be related to disordered cerebral autoregulation and endothelial dysfunction. Cerebral venous and sinus thrombosis (CVST) in the postpartum period is also a common cerebrovascular incident during the puerperium. Clinical manifestations consist of headache, vomiting, focal or generalized seizures, confusion, blurred vision, focal neurologic deficits, and altered level of consciousness. It is in the differential diagnosis when considering PRES in pregnancy in the post partum period.
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