Arterial
border zone infarcts in premature neonates lead to periventricular leukomalacia. Periventricular
leukomalacia is diagnosed by demonstrating increased echogenicity by brain
ultrasound that persists for more than 7 days or is associated with cavitation.
The increased echogenicity is best appreciated in the peritrigonal area
or in the frontal region. Cavitation occurs 2 to 6 weeks after the hypoperfusion
episode (Figure 247.1).
Figure 247.1.—
Diagnosis and evolution of periventricular leukomalacia. Increased ecogenicity
in the lateral angles of the lateral ventricles and in the peritrigonal
region (yellow arrows) at 7 days of age (7 D); cavitation (green arrows)
best seen at the frontal region at 20 days (20 D) and 37 days (37 D).
Cavitation
may be very extensive. Cavitation is better delineated by MRI of the brain
than by ultrasound (Figure 247.2). Periventricular leukomalacia may also
occur in neonates with ventriculitis, metabolic disorders, and hydrocephalus.
Periventricular leukomalacia is usually asymptomatic during the neonatal
period.
Figure 247.2.—
MRI of the brain demonstrating extensive periventricular leukomalacia.
Border
zone infarct in fullterm neonates
Arterial
border zone infarctions are less common in fullterm neonates. Arterial
border zone infarcts in fullterm neonates usually occur in the parasagittal
region because the irrigation of this zone is provided by the
terminal branches of the anterior, middle, and posterior cerebral arteries.
Periventricular leukomalacia, the typical findings
in arterial border zone infarct in premature neonates, can also occur
in term neonates. The pathogenesis and radiological findings of periventricular
leukomalacia are similar.
Single
artery brain infarct
Single
artery cerebral infarct occurs more frequently in the distribution of
the middle cerebral artery (Figure 247.3). The left hemisphere is more
frequently involved than the right hemisphere. Patients who have undergone
extracorporeal circulatory support are at risk for single artery brain
infarcts.
 A
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 B
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Figure 247.3.—
[A] CT of the brain demonstrating a large infarct in the distribution
of the middle cerebral artery. [B] MRI of the brain (T2-weighted
image) demonstrating a small posterior limb infarct in the internal capsule.
Multiple
artery brain infarcts
Multiple artery brain infarcts
occur less frequently than single artery brain infarcts. Meningitis
should be considered as a possible cause.
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