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Posterior reversible encephalopathy syndrome (PRES)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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posterior reversible encephalopathy syndrome (PRES)

  • is an acute or subacute cerebral syndrome

  • main manifestations of PRES include:
    • headache,
    • encephalopathy,
    • seizures, or
    • visual disturbances in various combinations

  • generally occurs in patients with:
    • acute, severe hypertension or moderate but acute elevations in blood pressure that are outside the accustomed range for the patient (1) or
    • exposure to certain drugs and toxic agents, mostly from chemotherapeutic drugs and immunosuppressive agents (1)
    • most plausible theory for PRES is that acute hypertension causes a breakdown of blood-brain barrier and resultant vasogenic edema (2)
      • predilection for the posterior circulation area would be explained by sparse sympathetic innervation of the vertebrobasilar system
      • acute hypertension is absent in about 1/4 of PRES patients
      • PRES can develop in patients with complex systemic conditions such as eclampsia, sepsis, autoimmune disease, after cancer chemotherapy, and after transplantation

  • white-matter vasogenic edema in the occipital and sometimes the adjacent parietal lobes are the most common abnormalites detected on neuroimaging (1)
    • diagnosis of PRES is based on relatively symmetric vasogenic edema of the white matter predominately localized in the area of posterior circulation, particularly in the parieto-occipital regions (2)
      • other structures including the brain stem, cerebellum, basal ganglia, and frontal lobes can occasionally be involved

  • if prompt recognition of PRES and the underlying cause is addressed, most patients recover (1)


  • posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS) are relatively uncommon neurological disorders, but their detection has been increasing mainly due to clinical awareness and spreading of magnetic resonance imaging (MRI) (3)
    • these syndromes share some common clinical and radiologic features and occasionally occur in the same patient, misdiagnosis may occur
    • PRES
      • is characterized by varied neurological symptoms including headache, impaired visual acuity or visual field deficit, confusion, disorders of consciousness, seizures, and motor deficits often associated to peculiar neuroradiological pattern even if uncommon localization and ischemic or hemorrhagic lesions were described
      • risk factors of PRES include:
        • immunosuppression,
        • malignancy,
        • pre-eclampsia,
        • renal failure,
        • autoimmune disorders,
        • sepsis, hypertension,
        • transplantation, and
        • chemotherapeutic medications
        • may occur also in healthy subjects
    • RCVS
      • is a group of diseases typically associated with severe headaches and reversible segmental vasoconstriction of cerebral arteries, often complicated by ischemic or hemorrhagic stroke
      • is the most important cause of thunderclap headache, commonly reversible, but several neurological complications including seizure, ischemic infarcts, and hemorrhage may happen (3)


  • (1) Geocadin RC. Posterior Reversible Encephalopathy Syndrome. N Engl J Med 2023; 388:2171-2178 DOI: 10.1056/NEJMra2114482
  • (2) Lee WJ, Yeon JY, Jo KI, Kim JS, Hong SC. Reversible Cerebral Vasoconstriction Syndrome and Posterior Reversible Encephalopathy Syndrome Presenting with Deep Intracerebral Hemorrhage in Young Women. J Cerebrovasc Endovasc Neurosurg. 2015 Sep;17(3):239-45. doi: 10.7461/jcen.2015.17.3.239. Epub 2015 Sep 30. PMID: 26523259; PMCID: PMC4626349.
  • (3) Pilato F, Distefano M, Calandrelli R. Posterior Reversible Encephalopathy Syndrome and Reversible Cerebral Vasoconstriction Syndrome: Clinical and Radiological Considerations. Front Neurol. 2020 Feb 14;11:34. doi: 10.3389/fneur.2020.00034. PMID: 32117007; PMCID: PMC7033494.

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