Posterior reversible encephalopathy syndrome: Co-relation between MR perfusion and the clinico-pathological spectrum

Objectives: The study was aimed to assess the epidemiological profile and patient characteristics, various morphological patterns of posterior reversible encephalopathy syndrome (PRES) on MRI and various pathophysiological mechanisms on MR perfusion.Methods: It was a prospective and observational study done over a total of 40 patients. Standard sequences included T1 and T2-weighted sequences, FLAIR, DWI, SWI and MR perfusion. Results: Females were affected predominantly with F:M ratio of 12:1. The commonest age group affected was between 20-40 years. The most common symptom was headache. The commonest etiology being pregnancy induced(37.5%).Hypertension was reported in 70%,out of which 37.5% included pregnancy induced hypertension. The commonest region involved was occipital lobe seen in 85% of patients. Atypical PRES was seen in 42.5% of patients in the form of involvement of atypical locations; basal ganglia 10%, thalami 2.5% and cerebellum 2.5%; diffusion restriction 12.5% and hemorrhage 22.5%, out of which 10% had subarachnoid hemorrhage,10% has intraparenchymal hematoma and 2.5% had minute focal hemorrhage. rCBV and rCBF was decreased in 82.5% of patients and unchanged in 12.5% of the total number of patients supporting the hypoperfusion theory.Conclusion: PRES predominantly involves female, hypertension is seen in most of the patients. The commonest lobes involved are the occipital and parietal lobes; however the incidence of atypical PRES is also seen in a significant number of patients. The basic pathophysiological mechanism is hypoperfusion.