Posterior Reversible Encephalopathy Syndrome

Introduction - Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiologic entity occurring in varied clinical setting and characterized by headaches, confusion, visual disturbances, seizures, and posterior transient changes on neuroimaging. The radiological features are often reported as demyelination which confounds the diagnosis. Observations - Of the 14 patients included for the study, 13 (93 percent) were females. The common symptom being Headache in 13 (93 percent), Seizure in 10 (71 percent), Visual disturbance in 7 (50 percent), altered sensorium in 7 (50 percent) and hypertension in 11 (78percent). On MRI the sites involved were Occipital 13 (92 percent), Parietal 9 (64 percent), frontal 4 (28 percent), temporal 2 (14 percent), deep nuclei 2 (14 percent), cerebellum 1 (7 percent) and brain stem 1 (7 percent). The symptoms were reversible in 12 (86 percent) patients, the remaining 2 (14 percent) had complications of PRES with 1 (7 percent) having right occipital infarct and 1 (7 percent) right parietal hemorrhagic transformation. Discussion -Acute rise in blood pressure is one of the factors in the pathogenesis of PRES, degree of raise in blood pressure doesnt correlate with the clinical severity or radiological manifestations. Pathophysiology of PRES remains controversial with two main hypotheses contradicting each other. One being impaired cerebral autoregulation leading to increased cerebral blood flow (CBF) as noticed in severe hypertension, whereas the other postulate is endothelial dysfunction with cerebral hypoperfusion as in cases with normal blood pressure or on cytotoxic therapy. The common final outcome in both is alteration in cerebral perfusion with blood brain barrier dysfunction causing vasogenic cerebral edema. The common etiology of PRES in this study was eclampsia, autoimmune disease, renal disease and other causes. Conclusion - PRES can manifest with atypical features like normal blood pressure, presence of MRI evidence of infarct or hemorrhage. Clinical suspicion in appropriate setting will lead to early diagnosis and appropriate therapeutic intervention. Reversibility of the clinical and radiological abnormalities is contingent on ealy treatment. On the contrary when unrecognized, conversion to irreversible cytotoxic edema may occur.