Posterior Reversible Encephalopathy Syndrome with Atypical Presentation: A Pictorial Review on MR Imaging Features

Posterior reversible encephalopathy syndrome (PRES) refers to a clinical and radiologic entity with diverse clinical causes. Patients present with a variety of symptoms ranging from headache, altered mental status, seizures and vision abnormalities to loss of consciousness. In cases with severe clinical manifestations, such as coma and/or status epilepticus, admission to the intensive care unit may be required. PRES is usually characterized by altered signal intensity in subcortical white matter of posterior cerebral hemispheres in magnetic resonance imaging (MRI) studies and resolve in weeks with appropriate treatment. Diagnosis depends on combination of suggestive clinical findings and radiological features. With increasing experience on PRES, atypical imaging features are described in case series. In this pictorial review, wide imaging feature spectrum of PRES is illustrated including unusual locations and atypical manifestations. Since MRI contributes to an essential part of the diagnosis, atypical imaging features of this syndrome should be well known by physicians and radiologists in order to recognize and treat it immediately. In suitable cases with atypical radiological features in the absence of classical findings, diagnosis of PRES should be kept in mind to avoid delay in diagnosis and hence, permanent neurological sequela.