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Reversible Encephalopathy Syndrome
History
4 year old with new onset seizure 3 days into treatment of acute lymphoblastic leukemia with
vincristine, decadron and allopurinol.
Diagnosis
Reversible Encephalopathy Syndrome
Additional Clinical
On initial admission-Abnormal liver function tests (elevated bilirubin, alkaline phosphatase, lactate
dehydrogenase, AST, and ALT) and pancytopenia.
6 month followup MRI-Negative
Discussion
Posterior reversible encephalopathy syndrome (PRES) describes a constellation of symptoms and
imaging findings which are transient. Presenting symptoms may abrupt or insidious and may include
headache, altered mentation, visual deficits, or seizure. Hyperperfusion and breakthrough of the
blood-brain barrier with exudation of fluid, blood and/or macromolecules in the cerebral cortex and
subcortical white matter account for the imaging findings; atypical locations of the anterior cerebrum,
basal ganglia, brainstem and cerebellum can also be seen.
The posterior circulation is most commonly involved secondary to relative lack of sympathetic
innervation of arterioles (autoregulation), but anterior circulation can be variably affected. Signal
abnormalities are most conspicuous on T2-FLAIR. Histologic evaluation reveals vasogenic edema
without inflammation or ischemia and acute/chronic vessel injury.
Predisposing conditions associated with PRES include eclampsia/pre-eclampsia, hypertension,
immunosuppressive therapy, multiagent or high-dose chemotherapy, multisystem failure (in particular
hepatic and renal), shock, hypercalcemia, thrombocytopenia syndromes, and autoimmune disorders.
Findings
MR-Axial T2 and T2-FLAIR images demonstrate areas of high signal in the cortex and subcortical
white matter in a parasagittal distribution.
Reference
Bartynski WS. Posterior reversible encephalopathy syndrome, part I: Fundamental imaging and
clinical features. AJNR (2008); 29:1036-1042.
McKinney AM, et al. Posterior reversible encephalopathy syndrome: Incidence of atypical regions of
involvement and imaging findings. AJR (2007); 189:904-912.
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