Inclusion Criteria:  Age >= 18 years ; Obtaining the non-opposition ; Patient hospitalized in ICU;  PRES diagnosed within the last 48 hours (before admission or during ICU stay), based on the following clinico-radiological criteria :  Presentation with acute clinical symptoms ; Presence of known risk factor for PRES; Distributions of T2 weighted imaging (T2WI) or T2-fluid attenuated inversion recovery (T2-FLAIR) hyperintensities compatible with PRES imaging patterns ; No other possible causes of these neuroimaging abnormalities found.  Exclusion Criteria:  Patient under legal protection ; Patient under guardianship or curatorship Pregnant women.