Posterior reversible encephalopathy syndrome (PRES), also known as reversible posterior leukoencephalopathy syndrome (RPLS), is a clinical syndrome consisting of rapid onset headaches, altered levels of consciousness, visual disturbances, and seizures associated with characteristic radiologic findings on MRI including symmetric white matter edema in the posterior cerebral hemispheres, especially the parieto-occipital regions. Occasionally, gray matter is involved. Headaches are typically moderate to severe, nonlocalized, and unresponsive to analgesia. Seizures may be the presenting manifestation and are usually generalized tonic-clonic. Altered consciousness ranges from confusion and mild somnolence to coma.

Physical examination often reveals hypertension and detectable visual perception abnormalities, including hemianopia, cortical blindness, or visual neglect. Reflexes are brisk and Babinski sign is often present. Risk factors for development of RPLS include hypertension, eclampsia, and immunosuppressive therapy, especially cyclosporine, tacrolimus, sirolimus, cisplatin, and rituximab.

Treatment is aimed at the precipitating cause, and prompt treatment is necessary given the potentially reversible nature of the condition. Onset is usually over hours to a day. Most patients recover within 2 weeks, with few patients having residual neurologic deficits.