Posterior Reversible Encephalopathy Syndrome

Posterior reversible encephalopathy syndrome (PRES) is a neurological condition that has a few other common references from reversible posterior leukoencephalopathy syndrome (RPLS), reversible posterior cerebral edema syndrome, posterior leukoencephalopathy syndrome, hyperperfusion encephalopathy, and brain capillary leak syndrome. It can present with a variety of symptoms such as altered mentation or stupor, drowsiness, visual disturbances (e.g., visual hallucinations, cortical blindness, hemianopia, quadrantanopia, and diplopia), seizures (focal or general tonic-clonic), and headaches. PRES can present acutely or subacutely, with symptoms developing within hours to days. Often, the presentation occurs in the context of acute uncontrolled hypertension, with systolic blood pressures ranging between 160 to 190 mmHg. The name is designated to its clinical and radiographic syndrome that is inspired by (1) radiographic findings of white matter edema (i.e., hyperintense T2 signal or hypointense T1 signal on magnetic resonance imaging (MRI)), typically found in the posterior cerebrum in a symmetric fashion (although asymmetric presentations are possible); and (2) the fact that symptoms are reversible, provided that the syndrome is recognized and treated promptly. However, the name used to describe the syndrome can be misleading as the edema is not always localized necessarily to the posterior cerebral white matter as it can occur in watershed zones other than parietal-occipital regions thalamus, and sometimes in the anterior circulation. Moreover, the syndrome is not always reversible. Some individuals can develop life-threatening complications, such as transforaminal cerebellar herniation and focal neurologic deficits, especially if prompt treatment is not initiated.