Ministry of Health
Isolated Frontal Horn Paraventricular Cysts
|Frontal horn cysts are an occasional finding
in preterm infants having cranial ultrasound scans for
They are differentiated
from periventricular leukomalacia by
their position - they are generally more anterior than the lesions seen
with PVLM, and lie below the lateral margin of the lateral ventricle.
Despite their impressive appearance, in isolation they are not
considered to be associated with a poor long-term neurodevelopmental
|Lenticulostriate vasculopathy is again an
occasional finding in infants who are undergoing
The appearance is
one of prominent outlining of blood vessels in the deep cerebral
circulation, presumably from calcification.
The aetiology is unclear, and in most infants no clearly identifiable
cause will be found. The lesions have, however, been associated
with CMV infection and with cerebral ischaemia.
|These images show marked ventricular
dilatation in a newborn infant. The lateral ventricles are grossly
enlarged, as is the third ventricle. The underlying pathogenesis
is due to an imbalance between CSF production and absorption, resulting
in accumulation of CSF within the ventricles. This may result from
a number of causes such as obstruction of flow, excessive secretion
(rare), or impaired absorption.
Congenital hydrocephalus can result
from a number of causes including
- intrauterine infection (toxoplasmosis, CMV, syphilis, and
- congenital aqueductal stenosis (may be X-linked)
- other congenital malformations of the CNS, such as
Dandy-Walker malformation and the Arnold-Chiari malformation
- Intracranial tumours
Causes of acquired hydrocephalus include
Treatment with an external reservoir or a ventriculo-peritoneal shunt
is often required. Medical treatment in neonates is generally
regarded as ineffective.
Vein of Galen Malformation
|Vein of Galen malformations
involve an aneurysmal dilatation of venous structures in the area of the
vein of Galen, although anatomical studies suggest that the vessel
involved is actually a primitive vascular structure (the median
prosencephalic vein of Markowski) that usually disappears by 11 weeks
There are usually multiple arterial connections to this structure,
resulting in a large vascular mass in the central structures of the
brain. Associated complications include
congestive cardiac failure
(secondary to high-output cardiac failure and myocardial ischaemia, with
resultant cerebral ischaemia), hydrocephalus (from compression of the
aqueduct), thrombosis of the vein of Galen with haemorrhagic infarction,
massive haemorrhage from rupture of the aneurysm, and atrophy secondary
to compression of adjacent structures by the intracranial vascular mass.
Clinical examination usually reveals
cardiac failure. A cranial
bruit is usually heard. Despite the size of the lesion,
neurological signs are unusual.
The natural history is for high mortality in the newborn period with
a high rate of significant disability in survivors. Management is
a major therapeutic challenge. Surgical approaches are difficult,
and frequently the infants are in significant congestive cardiac
failure. Therefore, approaches have moved towards embolisation of
the lesion to reduce flow.
Intracranial Tumour and Agenesis of the Corpus Callosum
|Some abnormalities of brain development or
formation may be detected on antenatal imaging. Cerebellar hypoplasia
has a variable clinical phenotype, with some affected individuals having
normal development whilst others may have difficulties with
developmental delay, hypotonia, ataxia and sometimes associated seizures
or specific speech delay.
It is important, particularly if there is a
significant amount of CSF in the posterior fossa, to differentiate this
from a Dandy-Walker malformation (cystic dilatation of
the 4th ventricle, complete or partial agenesis of the cerebellar vermis,
and hydrocephalus, with elevation of the tentorium).
Another condition that can cause a large posterior fossa cystic
lesion is Joubert's Syndrome (absence or underdevelopment of the
cerebellar vermis with abnormalities of the brain stem), commonly
associated with ataxia, hyperpnea, sleep apnea, abnormal eye and tongue
movements, and hypotonia. Malformations (e.g. extra fingers and toes,
cleft lip or palate, and tongue abnormalities) may also be present.
Similarly, Carbohydrate Deficient Glycoprotein Syndrome may be
associated with cerebellar hypoplasia (and brain stem abnormalities).
The images to the left show two views on a postnatal ultrasound of an
infant who had a large cystic space detected on an antental scan. The
postnatal imaging confirmed a large cystic space containing CSF in the
posterior fossa, with a degree of hypoplasia of the cerebellum.
These findings are also shown on the MRI images. No other
abnormalities were detected.
||Congenital Cytomegalovirus (CMV) infection is
thought to occur in 1% of all livebirths. Most infants are
asymptomatic but some have symptoms which can include microcephaly,
hepatosplenogmegaly, fulminant hepatic failure, thrombocytopenia, and
petechiae. There can be late sequelae of developmental delay and
progressive hearing impairment.
Imaging may demonstrate migrational disorders with microcephaly and
polymicrogyria, diminished white matter, delayed myelination, cerebellar
hypoplasia, and cerebral calcifications.
The images to the left from an infant with congenital CMV demonstrate
periventricular calcification, best shown in the left sagittal image as
three defined areas of increased echogenicity.