Diagnostic ultrasound ( PDFDrive )

CHAPTER 45 Neonatal and Infant Brain Imaging 1565
A
B
FIG. 45.63 Choroid Plexus Papilloma (Arrows) in Left Lateral Ventricle. (A) and (B) Coronal and sagittal sonograms. T, Thalamus; V, lateral
ventricle. (Courtesy of D. Pretorius, MD, University of California at San Diego.)
TABLE 45.3 Cystic Brain Lesions
Category
Normal variants
Congenital
Periventricular
Neoplastic
Inlammatory
Other
Sites of Arachnoid Cysts a
Anterior portions of middle cranial fossa
Suprasellar region
Posterior fossa
Quadrigeminal region
Cerebral convexities
Interhemispheric issure
a In decreasing order of frequency.
Speciic Lesions
Frontal horn cysts (connatal cysts,
coarctation of the lateral ventricle)
Choroid plexus cysts
Primary arachnoid cyst
Dandy-Walker malformation
Hydranencephaly
Holoprosencephaly
Periventricular leukomalacia
Subependymal cyst
Porencephalic cyst
Cerebellar astrocytoma (cystic type)
Craniopharyngioma
Teratoma
Abscess
Subdural empyema
Secondary arachnoid cysts
Vein of Galen malformation
frequently associated with other brain anomalies. With agenesis
of the corpus callosum, midline cysts are frequently continuous
with an elevated third ventricle. In alobar holoprosencephaly, a
dorsal cyst may be continuous with the single central
ventricle.
Porencephalic Cysts
Porencephalic cysts are a result of brain necrosis and cavitation,
which is continuous with the ventricular system (see Fig. 45.44).
hese lesions are usually caused by brain parenchymal hemorrhage,
infection, or surgery. 7
Choroid Plexus Cysts
Choroid plexus cysts are common and usually asymptomatic.
Choroid cysts occur in all age groups and are found in 34% of
fetuses and infants at autopsy. However, prenatal and neonatal
ultrasound reports have identiied choroid cysts in only approximately
1% of the populations studied. Choroid plexus cysts tend
to be single and occur as an isolated inding. However, large
(>10 mm) and multiple choroid cysts are occasionally associated
with chromosomal anomalies, particularly trisomy 18, 2 trisomy
21, and Aicardi syndrome. 228 Many other anomalies are typically
present in these newborns.
A choroid plexus cyst appears as a cyst with well-deined
walls within the choroid plexus (Fig. 45.64). Choroid cysts vary
in size from less than 4 mm to over 1 cm and are usually unilateral,
let greater than right, and situated in the dorsal aspect of the
choroid plexus. Rare cases of symptomatic choroid cysts causing
obstructive hydrocephalus have been reported but are probably
related to some speciic cause rather than a normal variant. 228
Occasional choroid cysts develop ater choroid plexus hemorrhage
into the ventricle. Color Doppler is helpful to distinguish vessels
in the choroid from cysts.