Neuroimaging features in posterior reversible encephalopathy syndrome: A pictorial review

Abstract

Posterior reversible encephalopathy syndrome (PRES) is a radioclinical entity associating nonspecific neurological symptoms (headache, seizures, impairment of alertness, visual disturbances…) occurring in evocative clinical condition (hypertension, eclampsia, immunosuppressor agents, systemic lupus erythematosus…). In the acute stage, the typical imaging finding is a vasogenic edema predominant in the subcortical parietal-occipital white matter. The purpose of this pictorial review is to illustrate the different neuroimaging features of PRES and present key radiological elements to assert diagnosis. In this overview, we examine the following points: the distributions of vasogenic edema, hemorrhage, the varying patterns in diffusion and perfusion, the different types of enhancement encountered and the vascular modifications demonstrated by angiography. The cause of PRES is still unknown. Nevertheless, catheter angiography, MR angiography and MR perfusion features in PRES render further insight into its pathophysiology. Follow-up imaging shows evidence of radiologic improvement in the very large majority of cases in 1 or 2weeks, sometimes in up to 1month. Recurrent PRES attacks are uncommon. Atypical imaging presentation should not reject the diagnosis of PRES in a compatible clinical situation.

Posterior reversible encephalopathy syndrome, a clinically diverse and challenging disorder

“…MRI is the principal diagnostic tool . With the exception of patient‐2, CT scans did not detect any of the lesions detected on MRI.…”

“…Lesions have a hyperintense signal on T2‐weighted and FLAIR sequences, characteristic of vasogenic edema. Usually, DWI with ADC map shows vasogenic edema with high ADC value, an indicator of their reversibility and thereby better prognostic outcome . However, contrary to its name, not all PRES lesions are reversible .…”

“…Furthermore, the radiological findings associated with PRES are not consistent as typically described. Lesions are not always reversible, and cortical involvement and affliction of other brain regions have a higher incidence than previously stated . PRES is associated with a number of medical conditions and therapeutic agents.…”

The clinical characteristics of posterior reversible encephalopathy syndrome in patients with chronic renal failure

“…PRES is typically diagnosed based on clinical symptom, imaging examination (computed tomography or magnetic resonance images) and predisposing factors such as acute hypertension, preeclampsia, cytotoxic or immunosuppressive medications (particularly cyclosporine) and connective tissue diseases (3). In addition, the most characteristic abnormality of PRES identified by neuroimaging is the presence of posterior white matter edema with symmetrical involvement of the parietal and occipital lobes for vascular cerebral dysregulation (4). The symptoms of PRES are generally reversible, however, in certain cases, cerebral hemorrhage or ischemia may occur and result in irreversible neurological deficits or death (2).…”

“…The majority of studies concerning PRES have only investigated its neurological symptoms and imaging findings and have not performed statistical analyses of biochemical indicators relevant to PRES (4,11). Renal dysfunction is a known cause of PRES (2), however the majority of patients with renal failure do not develop PRES, meaning that the exact nature of the relationship between CRF and PRES is unknown.…”