Posterior Reversible Encephalopathy Syndrome: Atypical

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Posterior Reversible Encephalopathy Syndrome
Atypical Unusual Imaging Manifestations
eSE number 49

• Petcharunpaisan S.1,2 Ramalho J.1,3 Castillo M.1
• 1University of North Carolina School of Medicine
• 2 King ChulalongKorn Memorial Hospital, Bangkok,
  THAILAND
• 3 Centro Hospitalar de Lisboa Central, EPE,
  Lisbon, PORTUGAL

2
Disclosures

• MC Editor in Chief, AJNR
• SP No disclosures
• JR No disclosures
• No authors have any activities that could
  represent a conflict of interest.

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Purpose

• Posterior reversible encephalopathy syndrome
  (PRES) is well recognized because of its typical
  imaging appearance, that is involvement of the
  parieto-occipital regions
• Other brain regions may also be affected and
  unusual imaging manifestations are observed
  frequently
• Purpose of this presentation is review the less
  common MR presentations of PRES and their best
  imaging approach

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Typical PRES

• PRES a neurotoxic state with unique imaging
  appearance
• Imaging typically shows areas of bilateral
  hemispheric edema affecting parietal and
  occipital lobes, followed by frontal lobes,
  inferior temporal occipital junctions and
  cerebellum

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Conditions at Risk for PRES
AJR 2008291036-42
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Typical PRES
A 12 yr-old-girl developed PRES after post
streptococcal glomerulonephritis and hypertension.
FLAIR images show high signal symmetrically
involving bilateral parieto-occipital, posterior
frontal, and temporo-occipital regions.
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Unusual Locations

• ? Focal/patchy areas of vasogenic edema may be
  seen in
• Basal ganglia and thalami
• Brainstem
• Deep white matter
  external internal capsule, corona
  radiata, splenium of corpus callosum
• Medulla oblongata and spinal cord
  at least 4 cases described, all are
  associated with hypertension

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Regional involvement by PRES in a series of 136
patients
AJNR 2007281302-07
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Regional involvement by PRES in a series of 76
patients
AJR 2007189904912
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Unusual Locations

• Involvement of basal ganglia, brainstem, and deep
  white matter are a less common but recognized
  part of PRES particularly when associated with
  abnormalities in the typical location
• Isolated unusual location in PRES, e.g.. central
  PRES with only basal ganglia and brainstem
  involvement, is rare but well known to occur

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Unusual Locations

• PRES may occasionally present with minimal or no
  detectable parietooccipital edema
• In such cases, it is necessary to exclude other
  causes, such as myelinolysis or encephalomyelitis
  using clinical history and follow-up imaging,
  when necessary

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Unusual Location
A 6-year old boy with sickle cell anemia
presented with alteration of consciousness,
headaches and seizures, and found to have
hypertension (200/100).
FLAIR images show high signal symmetrically
involving bilateral parieto-occipital lobes,
frontal lobes, bilateral cerebellar hemispheres
and splenium of corpus callosum.
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Unusual Location
39 year-old-female with severe hypertension,
developed severe headache and visual disturbances.
FLAIR images show high signal involving
bilateral parieto-occipital lobes, frontal lobes,
temporal lobes, bilateral basal ganglia, left
thalamus, pons and cerebellum.
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Unusual Location
A 10-year old boy with pyoderma gangrenosum,
presents with headache and seizures.
FLAIR images show high signal in
parasagittal frontal lobes, right
temporo-occipital lobe, midbrain, right basal
ganglia and thalamus, genu of corpus
callosum and cerebellum.
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Unusual Location
a
b
c
23 yr-old-male cocaine-induced malignant
hypertension, presenting

with headaches, confusion and spinal cord
syndrome.
T2W images show high signal in bilateral
parietal lobes (a), medulla oblongata
and cervical cord (b). Four weeks later
follow up shows resolution of cord lesions (c).
RadioGraphics 2007 27919940
16

• Enhancement (up to 37) cortical,
  leptomeningeal, parenchymal or pachymeningeal
• Restricted diffusion (11-26)
• Hemorrhage (10.5-17.1) parenchymal or
  subarachnoid
• Altered brain perfusion regional decreased or
  increased, depends on disease time course
• Unilateral hemispheric involvement (2.6)

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Restricted Diffusion
a
b
c
A 66 yr-old-female developed PRES after severe
hypertension.
FLAIR image (a) shows high signal involving
bilateral parieto-occipital lobes and splenium of
the corpus callosum with restricted diffusion on
DWI (b) and ADC map (c).
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Cortical Enhancement
A 66 yr-old-female developed PRES after severe
hypertension
FLAIR images (a,b) show high signal in
bilateral parieto-occipital lobes, cerebellum and
splenium of corpus callosum. Post
gadolinium T1WIs (c,d) show cortical enhancement
of lesions seen in FLAIR.
b
a
d
c
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Leptomeningeal Enhancement
9 year-old-boy developed PRES due to severe
hypertension.
FLAIR images (upper row) show high signal
in bilateral parieto-occipital and frontal lobes.
Post gadolinium images (bottom row) show
leptomeningeal enhancement.
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Subarachnoid Hemorrhage
50 yr-old-female developed PRES after severe
hypertension.
FLAIR image (A, B) show high signal in
bilateral occipital lobes, abnormal sulcal signal
in left frontal region. There is low signal on
GRE T2W (C), corresponding with sulcal hyper
attenuation on CT (D) due to subarachnoid
hemorrhage.
AJNR 200930137179
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Parenchymal Hemorrhage
a
b
c
52 yr-old-female post cardiac transplant
developed PRES possibly caused by tacrolimus
toxicity.
FLAIR images (a,b) show high signal in
bilateral parieto-occipital lobes. CT (c) done
next day shows parenchymal hemorrhage in previous
affected areas.
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Unilateral Involvement
12 yr-old-male presenting with headache and
seizures, found to have severe hypertension.
T2W images show high signal predominantly
in the left parieto-occipital and left temporal
regions.
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Decreased Brain Perfusion
a
b
A 10-year old boy with pyoderma gangrenosum,
presents with headache and seizures. PRES was
diagnosed possibly caused by Tacrolimus toxicity.
FLAIR images (a) show unusual locations of
PRES with minimal involvement
of fronto parietal lobes. ASL map (b)
shows decreased perfusion (blood flow) in
bilateral cerebral hemispheres, more on the left
side.
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Increased Brain Perfusion
a
b
c
A case of 33 yr-old-female with PRES.
DWI (a) and ADC (b) map show restricted
fluid diffusion in bilateral occipital lobes. ASL
map (c) shows increased perfusion in affected
regions.
AJNR 2008291428-35
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Summary

• Neuroradiologists should be aware that atypical
  imaging manifestations of PRES are more common
  than commonly perceived
• Recognition of atypical variants of PRES can be
  helpful to manage these patients and avoid
  complications in a timely manner

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