Posterior reversible encephalopathy syndrome

Objective: To evaluate the Magnetic Resonauce Imaging (MRI) features in patients having Posterior Reversible Encephalopathy Syndrome. Methods: This is a retrospective study from 8th June 2005 to 26th July 2009. Twelve patients were included who were confirmed to have Posterior Reversible Encephalopathy Syndrome, per imaging and clinical follow-up. Two neuro-radiologists blinded to the clinical condition retrospectively reviewed each image. Standard sequences were unenhanced Fluid Attenuated Inversion Recovery (FLAIR), T1-weighted, T2- weighted images followed by diffusion-weighted imaging and contrast-enhanced T1-weighted imaging. The regions involved were recorded on the basis of these sequences. Results: Abnormal T2-weighted hyperintense signals (indicating vasogenic oedema) were consistently present in the parietal or occipital regions in 5 (41.6%), but other locations were also involved, including the deep white matter in 3 (25%), frontal lobes in 1, inferior temporal lobes in 1, cerebellar hemispheres in 1, and basal ganglia in 1 (8.3% each). On follow-up examination after 5-7 weeks, the patients showed marked improvement clinically and on neuro-imaging, and were discharged in a stable condition. After administration of gadolinium contrast, there was no area of abnormal enhancement in 11 cases and minimal enhancement was seen in 1 case. In our series, 3 patients had follow-up MRI examination which revealed the resolution of previously seen changes as well as the resolution of clinical symptoms. However, the diagnosis of Posterior Reversible Encephalopathy Syndrome was established in 9 other patients by resolution of clinical symptoms alone in 2-3 weeks. Conclusion: Awareness of diverse clinical and radiographic presentation of acute Posterior Reversible Encephalopathy Syndrome is essential to avoid misdiagnosis and treatment delay. Moreover, the syndrome is reversible with prompt treatment and has good outcome. This case series confirmed clinical improvement and recovery in most patients within weeks.