What is Posterior Reversible Encephalopathy Syndrome (PRES)?

From the Guidelines

PRES syndrome, or Posterior Reversible Encephalopathy Syndrome, is a neurological condition characterized by temporary brain dysfunction due to swelling in the posterior regions of the brain, typically triggered by severe hypertension, and is fully reversible with timely recognition and management. The condition is often associated with hypertensive encephalopathy, which occurs when blood pressure is markedly elevated and cerebral autoregulation cannot prevent a rise in intracranial pressure, leading to cerebral edema, microscopic hemorrhages, and infarctions 1. Some key features of PRES syndrome include:

• Characteristic white matter lesions in the posterior regions of the brain, which can be visualized through magnetic resonance imaging (MRI) with increased signal intensity on T2-weighted or fluid attenuated inversion recovery (FLAIR)-imaging 1
• Reversible nature of the condition with prompt treatment, which focuses on addressing the underlying cause, such as controlling blood pressure or discontinuing triggering medications
• Potential for permanent brain damage if diagnosis or treatment is delayed, making early recognition crucial Common symptoms of PRES syndrome include headaches, confusion, seizures, visual disturbances, and sometimes loss of consciousness, which can be triggered by various factors, including severe hypertension, certain medications, eclampsia in pregnant women, kidney disease, or autoimmune disorders 1. Diagnosis is typically confirmed through MRI imaging, which shows characteristic white matter changes in the posterior brain regions, while computerized tomography (CT) is useful to exclude intra-cerebral hemorrhage 1. Overall, prompt recognition and management of PRES syndrome are essential to prevent permanent brain damage and ensure full reversibility of the condition.

From the Research

Definition and Characteristics of PRES Syndrome

• Posterior Reversible Encephalopathy Syndrome (PRES) is an acute neurotoxic syndrome characterized by a spectrum of neurological and radiological features from various risk factors 2.
• Common neurological symptoms include headache, impairment in level of consciousness, seizures, visual disturbances, and focal neurological deficits 2, 3, 4.
• The classic radiographic findings include bilateral subcortical vasogenic edema predominantly affecting the parieto-occipital regions, but atypical features include involvement of other regions, cortical involvement, restricted diffusion, hemorrhage, and contrast enhancement 2, 3.

Triggering Factors and Risk Factors

• Common triggering factors include blood pressure fluctuations, renal failure, eclampsia, exposure to immunosuppressive or cytotoxic agents, and autoimmune disorders 2, 5, 4.
• Populations at most risk for PRES include those with chronic hypertension, chronic renal disease, autoimmune disease, and immune suppression 6.

Diagnosis and Management

• Frequent neurological evaluations and neuroimaging examinations by computed tomography or magnetic resonance imaging are required for both the diagnosis and assessment of the condition 4.
• Early identification and appropriate management of PRES, including parenteral anti-hypertensives with proper blood pressure monitoring, decrease morbidity and mortality without chronic neurologic sequelae 6.
• The pillars of diagnosis and management can be initiated in the emergency department, including a diagnosis made by a thorough history and physical exam and cerebral imaging 6.