Diagnostic ultrasound ( PDFDrive )

1560 PART V Pediatric Sonography
associated with CMV and chorioretinitis associated with toxoplasmosis.
Intracranial calciications have been described in both
infections. CMV classically causes periventricular calciications
(see Fig. 45.56, Videos 45.17 and 45.18). Ventricular septations
have also been described (Video 45.19). Toxoplasmosis causes
more scattered calciications with a predilection for the basal
ganglia. However, both patterns have been seen in both infections.
201 Resolution of intracranial calciication has been reported
ater treatment of congenital toxoplasmosis, consistent with
improved neurologic outcome. 202
Sonography can demonstrate the periventricular or scattered
cerebral calciications as echogenic foci with or without acoustic
shadowing. In eight proven cases of CMV, Malinger and colleagues
200 reported periventricular hyperintensity in all cases, as
well as calciication, ventriculomegaly, hypoplastic vermis,
periventricular cysts, intraventricular adhesions, and echogenic
vasculature in the basal ganglia. Cerebellar calciication was seen
in one patient. 200 he brain parenchyma may appear disorganized,
with poorly deined sulci and corpus callosum. CT demonstrates
the calciications to a better extent, but MRI shows abnormal
myelination or cortical dysplasias most reliably.
Recently, maternal Zika virus infection has been described
in Brazil and many other countries and is associated with fetal
microcephaly and severe cerebral damage. 203 Sonographic indings
are similar to severe forms of CMV with microcephaly, ventriculomegaly,
corpus callosum abnormalities, gray and white
matter loss, and cerebral calciications. 204-213
HSV-1 or HSV-2 may cause disease of the CNS, although
HSV-2 is more common in the neonate, and HSV-1 occurs
primarily in older children and adults. HSV-2 may be acquired
transplacentally or by vaginal exposure to herpetic genital lesions
during birth. he resulting encephalitis is typically difuse,
resulting in loss of gray matter–white matter diferentiation. (his
difers from the temporal lobe disease seen in older children
and adults with HSV-1.) Cystic encephalomalacia of periventricular
white matter and hemorrhagic infarction with scattered
parenchymal calciications frequently result. 214 Relative sparing
of the lower neural axis, including the basal ganglia, thalamus,
cerebellum, and brainstem, is typical. Infections acquired in utero
may lead to microcephaly, intracranial calciications, and retinal
dysplasias. 215
Since the widespread availability of rubella vaccine ater 1967,
congenital rubella has fortunately become extremely uncommon
in the Western world. Unfortunately, it remains a signiicant
problem in many other parts of the world. Subependymal cysts,
microcephaly, and vasculopathy have been described. 216
Neonatal Acquired Infections
Meningitis and Ventriculitis
Despite the development of antibiotics to treat bacterial infections,
there are now cases of methicillin-resistant infections, 217 and
bacterial meningitis remains a serious concern for infants and
children. Neonatal sepsis has a major impact on neurodevelopmental
outcome of extremely premature infants independent of
other risk factors. 218 Schlapbach and colleagues 218 found three
times the risk for cerebral palsy ater sepsis; proposed mechanisms
included direct brain damage from infection and secondary
arterial hypotension from septic shock.
During the irst month of an infant’s life, the two most common
infections result from Escherichia coli and group B streptococci.
Between 4 and 12 weeks, E. coli and Streptococcus pneumoniae
are the most common, and from 3 months to 3 years, H. inluenzae
is most frequent. Enteroviruses have been reported to cause
encephalitis as well. 219 Meningitis is usually a clinical diagnosis;
imaging is needed only to evaluate for complications or when
the patient’s clinical situation deteriorates. 31,216
Complications of meningitis include subdural empyemas or
luid collections (Figs. 45.57 and 45.58), cerebritis, abscess formation,
and venous sinus thrombosis. Infarctions can occur from
either arterial vasculitis or venous obstruction, as a result of
venous sinus thrombosis. Sonography can identify these complications
but is not speciic. Areas of increased or decreased echogenicity
of brain parenchyma or sulci may represent edema,
cerebritis, or evolving infarction (Fig. 45.59).
Ventriculitis, another complication of meningitis seen in 60%
to 95% of cases, is suggested by the sonographic indings of
hydrocephalus, echogenic debris within the ventricles, increased
echogenicity, or a shaggy ependymal lining or ibrous septa within
the ventricles (Fig. 45.60). Ultrasound is best for identifying
intraventricular septa formation compared with CT or MRI.
hese septations can result in shunt failure or allow bacteria to
escape antibiotic exposure. MRI and CT with enhancement are
more sensitive for localizing the complications of infection, such
as infarcts, venous sinus thrombosis, and extraaxial luid
collections.
INTRACRANIAL MASSES
Brain Tumors
In only 11% of children are brain neoplasms seen before 2 years
of age. Tumors that do occur before the age of 2 years are usually
congenital and may appear on prenatal ultrasound as polyhydramnios.
220 Tumors can be diicult to diagnosis in the neonate.
If the neoplasm causes hydrocephalus, signs and symptoms of
increased intracranial pressure, such as enlarging head size,
vomiting, or behavioral alteration, it may be recognized. More
speciic signs and symptoms depend on the location of the tumor,
such as cranial nerve indings or pituitary gland and hypothalamic
dysfunctions. In general, MRI is the imaging modality of choice
in these infants. However, with nonspeciic signs and symptoms,
including an enlarging head from hydrocephalus, ultrasound
may be the irst imaging procedure performed. Sonography can
delineate the tumor site and size and evaluate cystic and solid
components.
Tumors may manifest initially because of hemorrhage into
the tumor. In fact, because hemorrhage is so much more common
than tumor in newborns, it may be extremely diicult to differentiate
a simple hematoma from a tumor; both can be quite
echogenic. Any hemorrhage present in unusual circumstances
or in an unusual location should be investigated by contrastenhanced
CT or MRI, searching for an occult tumor. 7 For unusual
hemorrhage, follow-up scans are also helpful because clotting