Posterior reversible encephalopathy syndrome

Case contributed by Dr Antonio Rodrigues de Aguiar Neto


Headache, a mental disorder with disorientation and agitation in the postpartum period (puerperal).

Patient Data

Age: 15 years
Gender: Female

Computed tomography (CT) shows the brain parenchyma is preserved, with no intracranial hemorrhage or ischemic lesions. The ventricular system and cisternal spaces appear normal. The visualized orbits, paranasal sinuses, and calvaria appear unremarkable.

Magnetic resonance imaging (MRI) demonstrates the bilateral cortex and subcortical white matter T2/Fluid-attenuated inversion recovery (FLAIR) hyperintensities in the posterior parietal lobes, which correspond to vasogenic edema, suggestive of PRES. The edema distribution is in the posterior cerebral artery (PCA) regions.  MR diffusion-weighted imaging (DWI) confirms that the area of abnormality represents vasogenic edema, without restricted diffusion. 

Case Discussion

Posterior reversible encephalopathy syndrome (PRES) is a clinical-radiological syndrome associated with some complex conditions such as preeclampsia/eclampsia, autoimmune disease, high dose cancer chemotherapy, after allogeneic bone marrow transplantation, solid organ transplantation, renal failure, and hypertension 1-5.

This syndrome manifests by a headache, altered mental status, seizures, and visual loss 1,3,4. It is commonly, but not always associated with acute hypertension.  A potentially reversible imaging pattern accompanies the disease 4.

PRES can have a variety of imaging findings on CT, MRI, and angiography 4. The typical findings are symmetric vasogenic edema affecting the parietooccipital cortex and subcortical white matter 1,3. PRES sometimes extend from the posterior to other parts of the brain such as the frontal and temporal lobes, basal ganglia, brain stem, and cerebellum. Lesion confluence may develop as the extent of edema increases 1.

Atypically unilateral or asymmetrical distribution of edema in PRES can occur 4,5. Besides, it may progress to atypical appearances including hemorrhage, contrast enhancement, or diffusion-weighted restriction 1,5.

Focal areas of restricted diffusion, similar to infarction or tissue damage with cytotoxic edema are uncommon 1. Atypical imaging findings should not dissuade the diagnosis of PRES in the appropriate clinical situation 4. Vasculopathy may be identified by CA or MRA.

Case courtesy

  • Erick Cavalcante, MD - PGY-3, Radiology Resident, Department of Radiology
  • Antonio Rodrigues de Aguiar Neto, MD - Radiologist, Department of Radiology
  •  Hospital da Restauração – Recife, PE – Brazil

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