Posterior Reversible Encephalopathy Syndrome

Posterior reversible encephalopathy syndrome (PRES)1,2 is an acute or subacute cerebral syndrome, the main manifestations of which are headache, encephalopathy, seizures, or visual disturbances in various combinations. The disorder typically occurs in patients with acute, severe hypertension or moderate but acute elevations in blood pressure that are outside the accustomed range for the patient, or exposure to certain drugs and toxic agents, mostly from chemotherapeutic drugs and immunosuppressive agents. Both drug and toxic exposures are probably related to cerebrovascular dysregulation or endothelial dysfunction. The most common abnormality detected on neuroimaging is whitematter vasogenic edema in the occipital and sometimes the adjacent parietal lobes. When PRES is promptly recognized and the underlying cause is addressed, most patients recover. An article by Hinchey et al.1 on an early series of cases of PRES described 15 patients with acute neurologic deficits that resolved within 2 weeks. Many subsequent articles have described various clinical features, particularly coma or focal neurologic deficits other than visual deficits (described below), an expanded list of triggering pathologic conditions, varied neuroimaging findings, the persistence of deficits, and outcomes of death. Although the term "PRES" has become common, the name no longer captures all the features of the disorder, and other terms have been used, including reversible posterior leukoencephalopathy, as in the article by Hinchey et al.