Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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December 22, 2016
Posterior Reversible Encephalopathy Syndrome (PRES)
- Background:
- Posterior reversible encephalopathy syndrome (PRES) is a noninflammatory cerebral vasculopathy due to cerebrovascular autoregulatory disorder or an endothelial dysfunction, usually related to a severe and quick rise of arterial blood pressure.
- Studies have also demonstrated association with specific drugs (e.g., Tacrolimus) and diseases (e.g., systemic lupus erythematous), even in the absence of hypertension.
- Clinical Presentation:
- Associated with headaches, seizures, impaired consciousness, and visual disturbances
- Key Diagnostic Features:
- Reversible cortico-subcortical hyperintensities on FLAIR/T2WI, usually without water restriction (vasogenic edema); commonly affects watershed zones of the parietal and occipital lobes (typical presentation) after episodes of high blood pressure
- Atypical PRES is characterized by similar lesions affecting the basal ganglia and frontal lobe and/or brainstem and cerebellum.
- After gaining control of the precipitating cause, lesions usually evolve to complete resolution. Rare cases may lead to permanent damage, usually caused by cortical/subcortical hemorrhagic foci.
- Differential Diagnoses:
- CNS vasculitis (including SLE): May be very difficult to differentiate from PRES, especially on the first studies; more likely to cause water diffusion restriction and permanent lesions than PRES. Lesions usually do not respond to arterial pressure control. The most specific imaging finding is vessel thickening and enhancement on post-contrast high-resolution T1WI, preferably with 3T MRI, to increase the relatively low sensitivity of vasculitis findings on MRA.
- Hypoglycemia: More likely to show restriction on DWI; usually spares cerebellum; always associated with low serum glucose levels (less than 50 mg/dL) of any etiology; reversibility depends of the duration and severity of hypoglycemia; extensive basal ganglia T2/FLAIR hyperintensities related to worse prognosis
- Cerebellar stroke: Acute cerebellar symptoms associated with FLAIR/T2 hyperintensities, with marked restriction on DWI, usually unilateral, respecting vascular territories; absence of rapid improvement with pressure control
- Treatment:
- Blood pressure control
- Treatment of the precipitating cause
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