Posterior Reversible Encephalopathy Syndrome (PRES) is characterized as reversible vasogenic cerebral edema in a posterior-dominant distribution. Some patients with PRES have diffusion-weighted imaging (DWI) changes on MRI, as well as transient arterial stenosis. We examined the association between arterial stenosis and presence of hemorrhage and MRI-DWI changes in PRES.

We retrospectively identified patients with PRES in electronic health records at a single health system from January 2008 to December 2018. We included patients age 18 years or older with clinical and radiographic evidence of PRES and arterial imaging (CT or MR angiography or digital subtraction angiogram). Any arterial stenosis was noted, with reversibility determined by repeat imaging. Patient characteristics, disease presentation, hospital lengths of stay and discharge dispositions, as well as imaging findings were collected and statistical analysis was used.

Of 281 patients with PRES, 169 had arterial imaging. Thirty-two (18.9%) had arterial stenosis and 60% had resolved arterial stenosis on follow-up imaging. Patients with arterial stenosis were younger compared to those without (47 v 55 years, p =0.03), however they did not differ in symptoms of presentation or comorbid conditions. Of note, arterial stenosis was associated with intracerebral hemorrhage [34% with stenosis and 18% without stenosis, p=0.05). However, the presence of MRI DWI lesions did not correlate with arterial stenosis [14/32 (44%) with stenosis, 49/137 (36%) without stenosis, p=0.42]. Among 97 patients with follow-up MRI, the presence of arterial stenosis was not associated with greater FLAIR reversibility. Furthermore, hospital length of stay or discharge disposition was not associated with arterial stenosis in PRES.

Arterial stenoses are found in 19% of PRES patients, and most are reversed on follow-up imaging. They are also associated with hemorrhagic PRES, but not with MRI-DWI lesions or degree of FLAIR reversibility.