1. EE-52: Unilateral Posterior Reversible Encephalopathy Syndrome (UPRES) in a Patient with Sickle Cell Disease Yankai Sun, MD, Shalabh Bobra, MD, Hasit Mehta, MD, Michael Tenner, MD, Brian Rigney, MD, Amrita Arneja, MD Department of Radiology, Westchester Medical Center New York Medical College, Valhalla, New York

2. Disclosure Authors have no disclosure.

3. Purpose To discuss the presentation, pathophysiology and imaging appearance of posterior reversible encephalopathy syndrome (PRES). To illustrate the imaging appearance of an unusual unilateral variant of posterior reversible encephalopathy syndrome (UPRES) in a patient with sickle cell disease.

4. Purpose Posterior reversible encephalopathy syndrome (PRES) –A reversible neurologic syndrome –Variety of presenting symptoms and causes. Typical presenting symptoms of PRES –Headache, seizure, altered mental status or vision loss. Common causes of PRES –Hypertension, pre-eclampsia/eclampsia, immunosuppressive therapy, severe hypercalcemia, or thrombocytopenic syndromes.

5. Purpose Imaging appearance –Classic PRES shows signal hyperintensity in the bilateral parieto- occipital and/or posterior frontal cortical and subcortical white matter on FLAIR (fluid-attenuated inversion recovery) images. Classic PRES. Axial T2- weighted FLAIR image of a different patient which demonstrates subcortical signal hyperintensity in the bilateral parieto-occipital lobes.

6. Purpose Imaging appearance (cont.) –Diffusion-weighted imaging (DWI) More than 50% show edema isointense to normal appearing parenchyma. 28% may have “T2 shine-through” hyperintensity on FLAIR and DWI. Less than 20% may show restricted diffusion. –Atypical involvement includes the brainstem, basal ganglia, cerebellum, or the unilateral variant. Pathophysiology of PRES –Not entirely clear but widely discussed hypothesis includes: Hyper-perfusion state with blood brain barrier and endothelial damage resulting in capillary leakage and subsequent cortical and subcortical edema.

7. Purpose Pathophysiology of PRES (cont.) –PRES favors the posterior cerebral circulation. –Relative lack of arteriole sympathetic innervation in the posterior circulation. –Sympathetic innervation presumably protects marked increased intravascular pressure. –Disruption of blood brain barrier and endothelial damage lead to loss of autoregulatory capability. Atypical locations of PRES –Brainstem –Basal ganglia –Cerebellum –Unilateral variant UPRES only accounts for 2-3% of all patients with PRES.

8. Purpose Sickle cell disease (SCD) –Autosomal recessive –Defect in the beta-chain hemoglobin –Microvascular occlusion –Bone infarct and osteomyelitis –Moyamoya disease Cerebrovascular involvement in patients with SCD –Cerebral infarct –Hemorrhage We present a patient with SCD, chronic left middle cerebral artery occlusion and Moyamoya disease who develops new onset of right-sided UPRES.

9. Case Report 12 y.o. male with history of sickle cell disease Sudden onset of severe headache, visual disturbance and hypertension on post haploidentical stem cell transplant day 20. Patient’s clinical and radiologic presentations are highly compatible with UPRES.

10. Image Findings Fig. 1 Axial T2-weighted FLAIR (fluid-attenuated inversion recovery) image shows cortical and subcortical signal hyperintensity in the right temporo-occipital region. Fig. 2 Axial T2-weighted image demonstrates corresponding T2 signal hyperintensity in the same area. Fig. 1Fig. 2

11. Image Findings Fig. 3aFig. 3b Fig. 3 (a an b) Axial diffusion weighted images demonstrate no evidence of restricted diffusion in the right temporo-occipital region.

12. Image Findings Fig. 4a MR angiography of the anterior circulation reveals occlusion of the left middle cerebral artery. Fig. 4b MR angiography of the posterior circulation demonstrates no evidence of basilar or posterior cerebral arterial occlusion. Fig. 4aFig. 4b

13. Image Findings Fig. 5 (a and b) Axial T2-weighted images at different levels demonstrate diffuse left cerebral atrophy, likely related to left middle cerebral artery occlusion and chronic left cerebral infarct. Fig. 5aFig. 5b

14. Image Findings Fig. 1 Axial T2-weighted FLAIR image at presentation shows cortical and subcortical signal hyperintensity in the right temporo-occipital region. Fig. 6 Two week follow up axial T2-weighted FLAIR image demonstrates complete resolution of abnormal signal hyperintensity in the right temporo-occipital region. Fig. 1Fig. 6

15. Summary Posterior reversible encephalopathy syndrome –A reversible neurologic syndrome with a variety of presenting symptoms and causes. –Classic PRES shows symmetric bilateral T2 signal hyperintensity involving the parieto-occipital and posterior frontal white matter. –Posterior cerebral circulation predilection. –Relative lack of arteriole sympathetic innervation in the posterior circulation. –Disruption of blood brain barrier and endothelial damage lead to loss of arteriole autoregulation. –UPRES only accounts for 2-3% of all patients with PRES.

16. Summary Sickle cell disease –Autosomal recessive –Defect in the beta-chain hemoglobin –Microvascular occlusion –Bone infarct and osteomyelitis –Moyamoya disease UPRES in a patient with SCD –Unclear etiology –Modifying factors may have played a role to give this unique presentation. Left internal carotid artery occlusion Chronic left cerebral infarct

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