La leucoencéphalopathie postérieure réversible

Posterior-reversible encephalopathy syndrome (PRES) is a rare complication related to a huge elevation in blood pressure occurring most often in patients with chronic hypertension. However, PRES may sometimes be observed in association with other conditions, including central nervous system collagen diseases, vasculitis, ionic disturbances as well as cytotoxic or immunosuppressive treatments. PRES is responsible for various but non specific neurological symptoms, including confusion, coma, seizures as well as visual disturbances. Diagnosis is performed using cerebral MRI which typically shows at the early stage, symmetric bilateral parietooccipital hyperintensities on T2 and fluid-attenuated inversion recovery (FLAIR) sequences. The apparent diffusion coefficient is either normal or mildly elevated related to cerebral tissue vasogenic edema. They are usually reversible after treatment of the underlying cause and reduction of blood pressure. In some cases, cerebral MRI may show lesions with a reduction of diffusion related to cytotoxic edema secondary to ischemia. Such lesions can lead to permanent neurological deficit.