OTHER VASCULAR DISORDERS

Posterior Reversible Encephalopathy Syndrome (PRES)

Created 23/11/2021, last revision 05/11/2023

• clinical-radiologic syndrome
• sometimes called reversible posterior leukoencephalopathy syndrome ( RPLS) or acute hypertensive encephalopathy
• the name may be misleading:
  • pathologic 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)

• 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, leading to vasodilatation, endothelial dysfunction, and subsequent vasogenic edema
  • reactive vasoconstriction is followed by 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 may lead to ischemia or hemorrhage
• lesions are typically localized in the parietal and occipital lobes (but may also be in the frontal and temporal lobes, cerebellum, and basal ganglia) [Legriel, 2011]

• headache (26%)
  • moderate-to-severe intensity
  • often poor response to analgesics
• nausea, vomiting
• encephalopathy with delirium/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 neurologic 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 neurologic signs by ≥ 24 h

• PRES is characterized by vasogenic edema involving the parietal and occipital lobes without clear territorial distribution, headache, and seizures
  • compared to ischemia, the foci are hyperintense on the ADC map
    
  • ischemia or hemorrhage may develop as a complication of PRES
• exclude:
  • severe hypoglycemia
  • acute 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

• with early treatment, the prognosis is good
• the prolonged duration may lead to irreversible neurological deficits
  

• most patients improve within 12-24 hours (up to several days) with prompt treatment
  
• MRI findings may persist for weeks
• delayed treatment can lead to serious complications (ischemic stroke/bleeding) with permanent disability
• death is usually caused by hemorrhage or massive edema in the posterior cranial fossa