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

To identify and define clinical associations and radiologic findings of posterior reversible encephalopathy syndrome (PRES). Patients prospectively diagnosed as having PRES from October 1, 2005, through April 30, 2009, were pooled with retrospectively identified patients admitted from August 1, 1999, through September 30, 2005. We performed a detailed review of clinical information, including demographics, presenting symptoms, medical history, and risk factors. All patients underwent computed tomography of the brain or magnetic resonance imaging. Findings on magnetic resonance imaging were analyzed independently by 2 neuroradiologists. We identified 120 cases of PRES in 113 patients (mean age, 48 years). Mean peak systolic blood pressure was 199 mm Hg (minimum-maximum, 160-268 mm Hg), and mean peak diastolic blood pressure was 109 mm Hg (minimum-maximum, 60-144 mm Hg). Etiologies of PRES included hypertension (n=69 [61%]), cytotoxic medications (n=21 [19%]), sepsis (n=8 [7%]), preeclampsia or eclampsia (n=7 [6%]), and multiple organ dysfunction (n=1 [1%]). Autoimmune disease was present in 51 patients (45%). Clinical presentations included seizures (n=84 [74%]), encephalopathy (n=32 [28%]), headache (n=29 [26%]), and visual disturbances (n=23 [20%]). In the 115 cases (109 patients) for which magnetic resonance imaging findings were available, the parieto-occipital regions were the most commonly involved (n=108 [94%]), followed by the frontal lobe (n=88 [77%]), temporal lobe (n=74 [64%]), and cerebellum (n=61 [53%]). Cerebellar involvement was significantly more frequent in patients with a history of autoimmunity (P=.008), and patients with sepsis were more likely to have cortical involvement (P<.001). A substantial proportion of patients with PRES have underlying autoimmune conditions that may support endothelial dysfunction as a pathophysiologic mechanism. On brain imaging, the location and severity of vasogenic edema were mostly similar for the different clinical subgroups.

Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state coupled with a unique CT or MR imaging appearance. Recognized in the setting of a number of complex conditions (preeclampsia/eclampsia, allogeneic bone marrow transplantation, organ transplantation, autoimmune disease and high dose chemotherapy) the imaging, clinical and laboratory features of this toxic state are becoming better elucidated. This review summarizes the basic and advanced imaging features of PRES, along with pertinent features of the clinical and laboratory presentation and available histopathology. Many common imaging/clinical/laboratory observations are present among these patients, despite the perception of widely different associated clinical conditions.

Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state accompanied by a unique brain imaging pattern typically associated with a number of complex clinical conditions including: preeclampsia/eclampsia, allogeneic bone marrow transplantation, solid organ transplantation, autoimmune diseases and high dose cancer chemotherapy. The mechanism behind the developing vasogenic edema and CT or MR imaging appearance of PRES is not known. Two theories have historically been proposed: 1) Severe hypertension leads to failed auto-regulation, subsequent hyperperfusion, with endothelial injury/vasogenic edema and; 2) vasoconstriction and hypoperfusion leads to brain ischemia and subsequent vasogenic edema. The strengths/weaknesses of these hypotheses are reviewed in a translational fashion including supporting evidence and current available imaging/clinical data related to the conditions that develop PRES. While the hypertension/hyperperfusion theory has been most popular, the conditions associated with PRES have a similar immune challenge present and develop a similar state of T-cell/endothelial cell activation that may be the basis of leukocyte trafficking and systemic/cerebral vasoconstriction. These systemic features along with current vascular and perfusion imaging features in PRES appear to render strong support for the older theory of vasoconstriction coupled with hypoperfusion as the mechanism.