Posterior Reversible Encephalopathy Syndrome (PRES)

An adult with acute kidney injury, a blood pressure of 200/120 mm Hg, headache, confusion, and a generalized seizure may initially appear to have an intracranial haemorrhage or ischemic stroke. A transplant recipient taking tacrolimus can develop the same syndrome with a much less dramatic blood pressure because endothelial toxicity, rather than pressure alone, may disrupt the blood–brain barrier. Posterior reversible encephalopathy syndrome is a clinicoradiographic emergency: acute neurologic symptoms occur with MRI evidence of predominantly vasogenic cerebral edema. The immediate priorities are airway and seizure safety, controlled treatment of severe blood-pressure elevation, identification and removal of the precipitating trigger, and assessment for hemorrhage, infarction, or dangerous edema. The name is a useful pattern clue, not a promise—lesions may extend beyond the posterior brain, and some patients sustain permanent injury.