Concept
Posterior reversible encephalopathy syndrome (PRES), also known as reversible posterior leukoencephalopathy syndrome (RPLS), is a rare condition in which parts of the brain are affected by swelling, usually as a result of an underlying cause. Someone with PRES may experience headaches, changes in vision, and seizures, with some developing other neurological symptoms such as confusion or weakness of one or more limbs. The name of the condition includes the word "posterior" because it predominantly though not exclusively affects the back of the brain (the parietal and occipital lobes). Common underlying causes are severely elevated blood pressure, kidney failure, severe infections, certain medications, some autoimmune diseases, and pre-eclampsia. The diagnosis is usually made by a brain scan (MRI) on which areas of swelling can be identified. The treatment for PRES is supportive: removal of the cause or causes and treatment of any of the complications, such as anticonvulsants for seizures. PRES may be complicated by intracranial hemorrhage, but this is relatively rare. The majority of people recover fully, although some may experience some residual symptoms. PRES was first described in 1996. PRES usually has an acute onset. Most people with PRES experience headaches and seizures; many also experience visual changes, confusion and drowsiness, weakness of the arm and/or leg on one side of the body (hemiplegia), difficulty speaking, or more rarely other neurological symptoms. Some people with PRES may experience coma. The visual changes in PRES may include hemianopsia (inability to see the left or right part of the visual field), blurred vision, lack of visual awareness on one side, visual hallucinations, and cortical blindness. Seizures occur in about two thirds of cases with seizures being the initial symptom in about 50% of cases. In children seizures may be seein in up to 90% of cases of PRES. If seizures occur they may be focal or generalized. About 18% of people who have seizures develop status epilepticus, where seizures are not controllable with simple measures.
