Posterior Reversible Encephalopathy Syndrome: Co-relation Between MR Perfusion And The Clinico-pathological Spectrum

Abstract

Background:Posterior Reversible Encephalopathy Syndrome or acute Hypertensive Encephalopathy is  a neurotoxic entity represented on MRI as bilateral parieto-occipital T2/FLAIR hyperintensities. However, the etiology remains unknown. Two common theories being 1)hypoperfusion and 2)hyperfusion of brain parenchyma.

Objectives: The study was aimed to assess the epidemiological profile and patient characteristics, various morphological patterns of PRES on MRI and various pathophysiological mechanisms on MR Perfusion.

Participants: It was done over a total number of 40 patients.

Study Design: It was a prospective and observational study.

Methods: 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 e.g. 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 females ,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 in the involved areas.

 Keywords :PRES, MR Perfusion