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
- pathologic changes may extend beyond the posterior regions
- 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
- 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]
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Clinical presentation
- 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
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 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
- compared to ischemia, the foci are hyperintense on the ADC map
- 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
Management
- with early treatment, the prognosis is good
- the prolonged duration may 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 to reduce mean arterial pressure (MAP) by 20-25% in the first 1-2 hours
- preferably use IV urapidil or labetalol
- the goal is to reduce mean arterial pressure (MAP) by 20-25% in the first 1-2 hours
- 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
Prognosis
- 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