Posterior reversible encephalopathy syndrome (PRES)

Case contributed by A.Prof Frank Gaillard


Failing renal transplant. Recent dramatic increased in blood pressure (>220mmHG systolic). Now obtunded.

Patient Data

Age: 20 years
Gender: Male

Acute intra-axial hemorrhage within the right corona radiata adjacent to the body of the caudate nucleus. Surrounding edema tracks inferiorly along the posterior limb of the right internal capsule.

Diffuse hypodensity involving the entire midbrain, pons and medulla as well as partial involvement of the cerebellar hemispheres more pronounced on the right. Ill-defined hypodensity within the white matter of the right superior frontal gyrus, lateral aspect of the right temporal lobe, anterior to the left lentiform nucleus and within the posterior aspect of the left temporal lobe. 

Normal appearance of the intracranial arterial circulation (CTA - not shown) of the brain, with no vascular malformation appreciated. No filling defects within the dural venous sinuses (CTV - not shown). 

A right frontal ventricular drain in situ. 

Edema seen throughout both cerebellar hemispheres and brainstem, with vasogenic edema ascending through the cerebellar peduncles into the internal capsule. The posterior fossa is very tight, with obliteration of the the pre pontine cisterns and inferior displacement of the cerebellar tonsils through foramen magnum. The perimesencephalic cisterns are also obliterated, as is the inferior aspect of the fourth ventricle. Resultant non-communicating hydrocephalous is noted.

In the right corona radiata a small focus of hemorrhage is demonstrated with surrounding residue edema, unchanged compared to the prior CT.

Only a trivial amount of blood product is seen in the right occipital horn, with no blood in the third ventricle, aqueduct or fourth ventricle. In addition to the aforementioned posterior fossa changes, subcortical white matter T2 hyperintensity is seen in the occipital lobes, without hemorrhagic change. No abnormal enhancement is demonstrated in the cerebellum, brainstem or cerebral hemispheres. A few punctate regions of restricted diffusion are present within the right cerebellar hemisphere. No cortical restricted diffusion.

MR venography (not shown) demonstrates normal flow and contrast induced signal within the dural venous sinuses, without features to suggest a deep vein thrombosis. 

MR angiography is unremarkable, with no focal stenosis, occlusion or beading.

Conclusion: Prominent cerebellar and brainstem edema and swelling with right corona radiata parenchymal hemorrhage in a patient who is immunocompromised and hypertensive has a relatively broad differential including: posterior reversible encephalopathy syndrome (PRES), rhomboencephalitis (e.g. viral or Listeria) and progressive multifocal leukoencephalopathy (PML). Of these, in the setting of hypertension and occipital subcortical T2 change and a hypocellular CSF posterior reversible encephalopathy syndrome (PRES) is favored. 

Case Discussion

The patient was aggressively treated with blood pressure control and made a near-complete recovery within 72 hours, extubated, GCS 15. This confirms the diagnosis of posterior reversible encephalopathy syndrome (PRES) and acts as a reminder that it need not be confined to the occipital lobes. 

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Case information

rID: 45130
Published: 9th Jun 2016
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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