1	REVERSIBLE POSTERIOR LEUKOENCEPHALOPATHY SYNDROME: ATYPICAL RADIOLOGICAL FEATURES Kader K. Oguz, Rahsan Gocmen, Burce Ozgen, Arzu Ozturk, Aysenur Cila Hacettepe University Hospitals, Department of Radiology, Ankara, TURKEY
2	Description and Background Reversible posterior leukoencephalopathy syndrome (RPLS) first described by Hinchey et al. as a clinicoradiologic entity in 1996. (N Engl J Med 1996;334:494-500) Clinical findings of the syndrome are headache, confusion, seizure and cortical blindness.
3	Pathophysiology Sudden elevations in systemic blood pressure loss of autoregulation of brain vasculature disruption of the blood-brain barrier capillary leakage vasogenic edema The selective involvement of structures perfused by the posterior circulation, likely due to relatively sparse sympathic innervation of the vertebrobasilar system
4	Predisposing Factors Hypertensive encephalopathy Eclampsia/preeclampsia Immunosuppressive agents (cyclosporine,vincristine….) Renal dysfunction Autoimmune diseases: systemic lupus erythematosus (SLE), polyarteritis nodosa (PAN) Thrombotic thrombocytopenic purpura (TTP) Hemolytic uremic syndrome Other separate individual cases reported
5	Classical Radiological Findings At the posterior circulation territoy Bilateral and relatively symmetric Sparing of paramedian occipital lobe structures In the subcortical white matter Vasogenic edema and increased diffusion Transient T2W hyperintensities
6	Material and Methods Between January 2002 and October 2005 14 patients (pts) (10 female, 4 male) Age range:6-72 (mean:25.6)yr All patients had routine MR imaging I.V Gd-DTPA was administered in 7 pts. 9 pts. had diffusion-weighted imaging (DWI) 8 pts. had computed tomography (CT) 7 pts. had follow-up MR imaging (1 week-16 months)
7	Radiological Evaluation Criterias In This Study Supra/infratentorial involvement Posterior/anterior circulation territory involvement White/gray matter involvement Basal ganglia involvement Thalamic involvement Brainstem involvement Cerebellar involvement DWI and apparent diffusion coefficiency (ADC) map findings Presence of hemorrhage MR angiography findings CT findings Presence of contrast enhancement Follow-up imaging findings
8	Table.1
9	Summary of MR Imaging Findings
10	Results The syndrome was more common in younger females (71% ) Of the 14 patients, 9 had multiple predisposing factors (minimum 3, maximum 5) The lesions were hemorrhagic in 3 patients Contrast enhancement was observed in 3 patients Restricted diffusion was observed in 2 patients Follow-up scanning showed complete or partial resolution in 6 patients but cortical tissue loss developed in 1 patient
11	Summary Of Atypical Radiological Findings In This Study Involvement of anterior circulation territory Cortical involvement Contrast enhancement Restricted diffusion Cortical tissue loss (irreversible)
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17	Nomenclature Hypertensive encephalopathy Reversible posterior leukoencephalopathy Posterior reversible encephalopathy syndrome Reversible occipitoparietal encephalopathy Focal acute cerebral edema syndrome Reversible edema syndrome Reversible posterior cerebral edema syndrome
18	REVERSIBLE POSTERIOR LEUKOENCEPHALOPATHY
19	REVERSIBLE POSTERIOR LEUKOENCEPHALOPATHY
20	REVERSIBLE POSTERIOR LEUKOENCEPHALOPATHY
21	Conclusion Classical MR imaging findings include bilateral, reversible, posterior white matter T2A hyperintensities of vasogenic edema as the current most frequently used name implies. However, cortical,infratentorial, anterior involvement and profound contrast enhancement were not uncommon as shown in the present study. Recognition of the atypical findings helps early diagnosis of this benign condition, avoid unnecessary diagnostic tests and allows for proper treatment finally.
22	References Hinchey J, Chaves C, Appignani B, et al. A reversible posterior leucoencephalopathy syndrome. N Engl J Med 1996;334:494-500. Toshiyuki Ohta Takashi Sakano, Mami Shiotsu, Takeki Furue, Hideyuki Ohtani, Yoshihisa Kinoshita, Tatsuya Mizoue, Katsuzo Kiya and Issei Tanaka Reversible posterior leukoencephalopathy in a patient with Wegener granulomatosis. Pediatr Nephrol. 2004 Apr;19(4):442-4. Ito Y, Arahata Y, Goto Y, et al. Cisplatin neurotoxicity presenting as reversible posterior leukoencephalopathy syndrome. AJNR Am J Neuroradiol 1998;19:415-417. Schwartz RB, Mulkern RV, Gudbjartsson H, Jolesz F. Diffusion-weighted MR imaging in hypertensive encephalopathy: clues to pathogenesis. Am J Neuroradiol 1998; 19:859-862. Provenzale JM, Petrella JR, Cruz LCH, Wong JC, Engelter S, Barboriak DP. Quantitative assessment of diffusion abnormalities in posterior reversible encephalopathy syndrome. Am J Neuroradiol 2001;22:1455-1461. Schwartz RB, Bravo SM, Klufas RA, et al. Cyclosporineneurotoxicity and its relationship to hypertensive encephalopathy: CT and MR findings in 16 cases. Am J Roentgenol 1995;165:627-631. Covarrubias DJ, Luetmer PH, Campeau NG. Posterior reversible encephalopathy syndrome: prognostic utility of quantitative diffusion-weighted MR images. Am J Neuroradiol 2002;23:1038-1048. Pavlakis SG, Frank Y, Chusid R. Hypertensive encephalopathy, reversible occipitoparietal encephalopathy or reversible posterior leukoencephalopathy: three names for an old syndrome. J Child Neurol 1999;14:277-281. Schwartz RB, Jones KM, Kalina P, et al. Hypertensive encephalopathy: findings on CT, MR imaging and SPECT imaging in 14 cases. Am J Roentgenol 1992;159:379-383.