Controversy of posterior reversible encephalopathy syndrome: what have we learnt in the last 20 years?

Abstract

Over two decades have passed since posterior reversible encephalopathy syndrome (PRES) was first described in 1996. It has becoming increasingly recognised because of improved and more readily available imaging modality. The exact pathophysiological mechanism is not completely understood and remains controversial at present. Precise diagnosis is essential to guide prompt, proper management. Our ability of differentiating it from other acute neurological disorders is likely to improve as we learnt more about the spectrum of this entity in the last 20 years. We emphasise the importance of recognising its diagnostic criteria and biomarker, which would be of great relevance to either outcome evaluation or study design. PRES has a favourable prognosis generally, but neurological sequelae and even fatalities can occur, especially in severe forms that might cause substantial morbidity and even mortality, particularly when the syndrome is complicated by intracranial haemorrhage or brain infarction. In this review, the pathophysiology, approach to diagnosis, some controversies as to the prognosis, as well as the future research direction of PRES are described.

Posterior Reversible Encephalopathy Syndrome and Reversible Cerebral Vasoconstriction Syndrome: Clinical and Radiological Considerations

“…PRES patients may show several neurological symptoms, commonly headache, impaired visual acuity, or visual field deficits, but confusion, focal neurological deficits, and disorders of consciousness with seizures may also occur. Clinical presentation has a great variability and course may depend on comorbidities and precipitating factors, but more than 90% of patients have typical clinical and neuroradiological features (34).…”

Imaging Patterns of Toxic and Metabolic Brain Disorders

“…Current theories have a similar shared mechanism, advocating endothelial injury and dysfunction secondary to different causes (cytotoxic, immunogenic), ultimately resulting in vasogenic edema. Interstitial fluid accumulates in the subcortical white matter, with a predilection for the parietal and occipital lobes (2,61,62). This condition occurs at all ages but is most common in young women (2).…”

“…Diffusion-weighted images and apparent diffusion coefficient maps are often negative (differentiating the condition from cytotoxic and intramyelinic edema) or at least have a smaller extension than those changes depicted on FLAIR images. Postcontrast enhancement is not a typical feature, but some studies report that up to 37% of cases depict contrast enhancement (61,62).…”

Posterior reversible encephalopathy syndrome as an underlying cause for encephalopathy in a sepsis patient in the intensive care unit: case report

“…[6,7] Clinical and radiological findings of PRES in hypertension, immunosuppressive treatment and rheumatological diseases have been shown to resolve over time, following prompt diagnosis and treatment; on the other hand, sepsis and septic shock are usually associated with worse prognosis in PRES. [7,8] On the pathophysiological level, the cellular processes leading to PRES in sepsis are still unclear. The vasogenic theory suggesting loss of autoregulation and leakage of fluid into the interstitial space due to abrupt hypertension may not apply to the septic patient in the majority of cases.…”

“…The vasogenic theory suggesting loss of autoregulation and leakage of fluid into the interstitial space due to abrupt hypertension may not apply to the septic patient in the majority of cases. [8,9] The endothelial damage theory hypothesizes an increase in blood pressure due to endothelial dysfunction. [10] The immunogenic theory, which is thought to involve activation of T cells and release of cytokines can be considered as the most relevant since cytokine-mediated mechanism inducing sepsis is very similar to those underlying PRES.…”