• clinical-radiological syndrome
  • sometimes called reversible posterior leukoencephalopathy syndrome ( RPLS) or acute hypertensive encephalopathy
  • the name can be misleading:
    • pathological changes may extend beyond the posterior regions
    • some patients may develop permanent brain damage with neurological deficits
  • diagnosis is based on imaging methods (mainly typical MRI findings on T2 and FLAIR)

Pathophysiology of PRES

  • there is no clear, exact etiology; probably, different conditions can lead to the same clinical presentation:
    • decompensated hypertension (~ BP > 170-190 mm Hg) impairs cerebral autoregulation, which leads to vasodilatation, endothelial dysfunction, and subsequent vasogenic edema
    • reactive vasoconstriction with subsequent hypoperfusion  [Bartynski, 2008]
    • a systemic inflammatory response with endothelial dysfunction ( a theory supported by the association with sepsis, pre-eclampsia, and autoimmune diseases), where released vasoactive substances increase vascular permeability (⇒ edema). In these patients, PRES may occur even with normal BP! [Kurukumbi, 2013]
  • changes are reversible with early therapy; prolonged duration can lead to ischemia or hemorrhage
  • localization of lesions is typically in the parietal and occipital lobes (but may also be in the frontal and temporal lobes, cerebellum, and basal ganglia) [Legriel, 2011]
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Clinical presentation

  • headaches (26%)
    • moderate-to-severe intensity
    • often poor response to analgesics
  • nausea, vomiting
  • encephalopathy with deliriant syndrome/quantitative disturbances of consciousness (from somnolence to coma) – exclude NCSE!
  • epileptic seizures (up to 90%, status epilepticus in approximately 3% of cases)
  • visual disturbances (26%)
    • hallucinations
    • cortical blindness, which may be associated with its denial (Anton-Babinski syndrome)
    • hemianopsia
    • papilledema with retinal hemorrhages and exudates
  • focal neurological signs (3-17%)
    • vertigo, ataxia, etc
  • poorly controlled blood pressure (67-80%)
    • no correlation between mean BP and severity of radiologic changes
    • hypertensive crisis may precede neurological signs by ≥ 24 h
Clinical presentation of PRES

Diagnostic evaluation

Computed tomography (CT)

  • negative findings or nonspecific hypodensities in the parietal and occipital regions bilaterally  PRES on computed tomography

Magnetic resonance imaging (MRI)

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Other diagnostic methods

  • lumbar puncture
  • blood tests (e.g., autoantibodies, Ca2+/S, Mg2+/S, etc.)
  • brain biopsy if an infiltrative process is suspected

 

Differential diagnosis

  • PRES is characterized by vasogenic edema involving parietal and occipital lobes without clear territorial distribution, headache, and seizures
    • compared to ischemia, the foci on the ADC map are hyperintense
    • ischemia or hemorrhage may develop as a complication of PRES
  • exclude:
    • severe hypoglycemia
    • acute the posterior circulation stroke
    • progressive multifocal leukoencephalopathy (PML)
    • sinus thrombosis
    • gliomatosis cerebri
    • hypoxic-ischemic encephalopathy
    • SMART syndrome (stroke-like migraine attacks after radiotherapy)
    • inflammatory cerebral amyloid angiopathy

→ DDx of leukoencephalopathies see here

Management

  • with early treatment, the prognosis is good
  • longer duration can lead to irreversible neurological deficits

Elimination of the cause of PRES

  • the cornerstone of the therapy is the elimination of the provoking moment:
    • normalize blood pressure, prevent its fluctuations
    • identify and discontinue toxic drugs
    • provoke delivery in case of eclampsia
    • correct metabolic disorders

Symptomatic therapy

  • antihypertensive therapy hypertensive crisis therapy see here
    • the goal is a 20-25% decrease in mean arterial pressure (MAP) in the first 1-2 hours
    • preferably use i.v. urapidil, labetalol
  • symptomatic treatment of seizures → see here
    • long-term therapy is usually unnecessary
  • correct potential hypomagnesemia
  • antiedema therapy according to the clinical condition and MRI findings
    • corticosteroids can theoretically improve edema, but there is no hard evidence of effectiveness
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Prognosis

  • most patients improve within 12-24h (up to several days) with prompt treatment
  • MRI findings may persist for weeks
  • delayed treatment can lead to serious complications (ischemic stroke/bleeding) with a permanent disability
  • death is usually caused by hemorrhage or massive edema in the posterior cranial fossa
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Posterior Reversible Encephalopathy Syndrome (PRES)
link: https://www.stroke-manual.com/posterior-reversible-encephalopathy-syndrome-pres/