OTHER VASCULAR DISORDERS

Posterior Reversible Encephalopathy Syndrome (PRES)

Created 23/11/2021, last revision 29/04/2023

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)

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, 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
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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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

negative findings or nonspecific hypodensities in the parietal and occipital regions bilaterally

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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 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

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

antihypertensive therapy → hypertensive crisis therapy see here
- the goal is to reduce mean arterial pressure (MAP) by 20-25% in the first 1-2 hours
- preferably use IV urapidil or labetalol
symptomatic treatment of seizures → see here
- long-term treatment is usually unnecessary
correct potential hypomagnesemia
antiedema therapy according to clinical status and MRI findings
- corticosteroids can theoretically improve edema, but there is no hard evidence of efficacy

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 permanent disability
death is usually caused by hemorrhage or massive edema in the posterior cranial fossa