From the Guidelines
PRES syndrome, or Posterior Reversible Encephalopathy Syndrome, is a neurological condition characterized by temporary swelling in the posterior regions of the brain, typically triggered by severe hypertension, and is fully reversible with timely recognition and management.
Key Characteristics of PRES Syndrome
- It typically presents with symptoms including headaches, confusion, seizures, visual disturbances, and sometimes loss of consciousness.
- The syndrome occurs when blood pressure rises so high that it overcomes the brain's ability to regulate blood flow, causing fluid leakage into brain tissues, as described in the management of hypertensive emergencies 1.
- Brain MRI is the preferred diagnostic tool, showing characteristic white matter changes in posterior brain regions, with magnetic resonance imaging (MRI) demonstrating increased signal intensity on T2-weighted or fluid attenuated inversion recovery (FLAIR)-imaging being of additional value to confirm the diagnosis 1.
Diagnosis and Treatment
- There is no specific BP threshold to define hypertensive emergencies, but the rate of BP increase appears to be more important than the absolute BP value in the development of hypertensive emergencies 1.
- Treatment focuses on controlling blood pressure, often with medications, and if medication-induced, the offending drug may need to be discontinued or its dosage reduced.
- Most patients recover completely within days to weeks with prompt treatment, though delayed diagnosis can lead to permanent brain damage.
Important Considerations
- The medical history-taking should focus on emergency symptoms, possible causes, and the use of drugs, as well as secondary causes, to guide the diagnosis and management of PRES syndrome 1.
- Emergency symptoms include headache, visual disturbances, chest pain, dyspnoea, and focal or general neurological symptoms, which should be promptly evaluated and addressed 1.
From the Research
Definition of PRES
- Posterior Reversible Encephalopathy Syndrome (PRES) is an acute neurotoxic syndrome characterized by a spectrum of neurological and radiological features from various risk factors 2.
- It is a clinical syndrome that refers to a disorder with reversible subcortical vasogenic brain edema caused by endothelial dysfunction, predominantly involving the bilateral parieto-occipital regions 3.
Clinical Features
- Common neurological symptoms of PRES include headache, impairment in level of consciousness, seizures, visual disturbances, and focal neurological deficits 2, 4, 5.
- Triggering factors for PRES include blood pressure fluctuations, renal failure, eclampsia, exposure to immunosuppressive or cytotoxic agents, and autoimmune disorders 2, 4, 5, 3, 6.
Radiographic Findings
- The classic radiographic findings of PRES include bilateral subcortical vasogenic edema predominantly affecting the parieto-occipital regions 2.
- Atypical features may include involvement of other regions, cortical involvement, restricted diffusion, hemorrhage, and contrast enhancement 2.
Treatment and Outcome
- Treatment of PRES is supportive and involves correcting the underlying cause and managing associated complications, such as seizures 5.
- Early detection and treatment of PRES are key for a rapid recovery and good prognosis 4, 6.
- Although most patients recover, PRES is not always reversible and may be associated with considerable morbidity and even mortality 2, 5, 6.