Posterior reversible encephalopathy syndrome: a variant of hypertensive encephalopathy.

Posterior reversible encephalopathy syndrome (PRES) is a recently described variant of hypertensive encephalopathy characterized by headache, visual disturbances and altered mental function. Its causes are diverse and in contrast to hypertensive encephalopathy, it can develop without significant elevation of blood pressure. This syndrome is mostly reversible when correctly managed; however, failure to recognize it can lead to cerebral infarction and death.