Posterior reversible encephalopathy syndrome


  • PRES, a rare syndrome characterized by acute neurological symptoms due to vasogenic edema in the posterior brain
    • Somewhat of a misnomer as changes seen on MRI are not limited to the posterior fossa and symptoms are not always reversible
    • Renamed reversible posterior leukoencephalopathy syndrome (RPLS) by the American Academy of Neurology
  • Risk factors: malignant hypertension, kidney disease, autoimmune disease, immunosuppression, eclampsia
  • Poorly understood entity, but thought to be due to 2 theoretical mechanisms:[1]
    • Hypertension-hyperperfusion: Hypertensive emergency causes vascular extravasation of fluid and vasogenic edema
    • Endothelial dysfunction: Autoimmune or cytotoxic etiologies lead to endothelial dysfunction, leading to increased vascular permeability and edema
  • Epidemiolgy: Most frequently in middle-aged females, which may be related to underlying disease[2]
  • Prognosis: While many case reports suggest PRES is benign and fully reversible, the consequences of PRES, including intracerebral hemorrhage or extensive intracerebral edema, can result in residual neurologic deficits
Magnetic resonance image showing multiple cortico-subcortical areas of hyperdense signal involving the occipital and parietal lobes bilaterally and pons in a patient with posterior reversible encephalopathy syndrome

Clinical Features[3]

Differential Diagnosis[5]



  • CT head to rule out other etiologies
  • MRI often shows symmetrical cerebral edema, showing as hyperintensities on T2-weighted image in the posterior circulation, most commonly in the parietal-occipital areas[5]
    • However, any brain region can be involved, including the frontal and temporal lobes
  • Focus on altered mental status workup, with PRES as diagnosis of exclusion
  • Consider lumbar puncture if there is a concern for meningitis or encephalitis
  • May require EEG for detection of status epilepticus


  • Treat the underlying etiology
  • Control Blood Pressure, considering gradual reduction to avoid sudden hypoperfusion
  • Discontinue immunosuppressants or cytotoxic medications
  • Standard seizure management, if seizures are present
  • In cases related to Preeclampsia or HELLP syndrome, consider early OB/GYN consultation for delivery[6]


  • Admit
    • Consider ICU for blood pressure titration, obtunded state, status epilepticus, intracranial hemorrhage, or other serious sequelae

See Also


  1. Zelaya JE, Al-Khoury L. Posterior Reversible Encephalopathy Syndrome. [Updated 2022 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.
  2. Fischer M, Schmutzhard E. Posterior reversible encephalopathy syndrome. J Neurol. 2017 Aug;264(8):1608-1616. doi: 10.1007/s00415-016-8377-8. Epub 2017 Jan 4. PMID: 28054130; PMCID: PMC5533845.
  3. Staykov D. "Posterior reversible encephalopathy syndrome". PMID 21257628
  4. Fugate JE, Claassen DO, Cloft HJ, Kallmes DF, Kozak OS, Rabinstein AA. Posterior reversible encephalopathy syndrome: associated clinical and radiologic findings. Mayo Clin Proc. 2010 May;85(5):427-32. doi: 10.4065/mcp.2009.0590. PMID: 20435835; PMCID: PMC2861971.
  5. 5.0 5.1 Garg RK (January 2001). "Posterior leukoencephalopathy syndrome". Postgrad Med J 77 (903): 24–8. doi:10.1136/pmj.77.903.24. PMC 1741870. PMID 11123390
  6. Parasher A, Jhamb R. Posterior reversible encephalopathy syndrome (PRES): presentation, diagnosis and treatment. Postgrad Med J. 2020 Oct;96(1140):623-628. doi: 10.1136/postgradmedj-2020-137706. Epub 2020 May 28. PMID: 32467104.