- Enlargement of the cerebral ventricles can be seen on fetal ultrasound scans
from about 14 weeks gestational age. Ventriculomegaly is
diagnosed when the width of the atrium of the lateral ventricle is ≥10mm
(which is ≥4SD above the mean of 7.6 ±5mm) regardless of gestation.1
The degree of enlargement is classified as:
◗ mild—10–12mm;
◗ moderate—12.1–15mm;
◗ severe—>15mm
The measurements should be made in the transverse diameter of the lateral
ventricle on an axial plane, at the level of the glomus of the choroid plexus - INVESTIGATIONS
A thorough tertiary level antenatal ultrasound scan should be done to
identify the possibility of other abnormalities. Fetal magnetic resonance
imaging (MRI) should also be considered.
Maternal serology should be done to test for evidence of infections
(including cytomegalovirus, toxoplasmosis, herpes, parvovirus, human
immunodeficiency virus [HIV]).
Fetal karyotype is recommended.
PROGNOSIS
Not all fetuses will survive to delivery as there is an increased chance
of intra-uterine fetal death during pregnancy and delivery (10% for
moderately severe ventriculomegaly and 25% for severe).5
The prognosis is ultimately determined by the primary aetiology and the
presence of associated abnormalities. If the ventriculomegaly is isolated, the
chance of normal neurodevelopmental outcome is as follows2,7,8
◗ 90–95% if mild;
◗ 80–84% if moderate; and
◗ 10–60% if severe. - Below is a list of factors which may influence prognosis:
◗ unilateral dilatation appears to have a better prognosis;
◗ asymmetrical bilateral dilatation (>2mm difference) in one study was
associated with a worse outcome—50% had neurological impairment;2
◗ prenatal progression (increase of >3mm) is associated with a worse
outcome;2 and
◗ the presence of associated white matter abnormalities significantly
increases the risk of adverse outcome - MANAGEMENT—ANTENATAL
The options of termination of pregnancy or postnatal palliative care
should be discussed with the parents, particularly if significant associated
abnormalities have been identified.
If there is significant hydrocephalus, consider elective caesarean section.
In view of increased incidence of fetal death, if active management is
requested, pregnancy should not be allowed to go post-term.
If there is macrocephaly with severe ventriculomegaly, the ventricles can
be drained before delivery. This may decrease the likelihood of a traumatic
caesarean section,9 but will significantly increase the risk of fetal demise. - If significant abnormalities have been identified and active management
is warranted, then delivery should occur at a hospital with an intensive care
nursery.
MANAGEMENT—POSTNATAL
The baby should be closely examined for other abnormalities.
A cranial ultrasound scan should be done to establish the degree of
ventriculomegaly. If required, neurosurgical review should be arranged.
A magnetic resonance imaging (MRI) scan should be considered
to identify other central nervous system abnormalities not previously
identified.
Chromosomal studies should be done (if they have not been done
antenatally). If a syndrome has been identified, consider parental
chromosomes looking for balanced translocation or mosaicism.
A full blood count and film examination is done to determine the
platelet count. If the platelet count is low, the parents may need testing the
for alloimmune thrombocytopaenia.
Coagulation studies should be done if intraventricular haemorrhage is
considered a possible cause. - An ophthalmology assessment and an auditory assessment should be
done before hospital discharge.
Long-term neurodevelopmental follow-up by a paediatrician will be
required.
RECURRENCE
Referral should be made to a genetic service to appropriately counsel
parents about risk in subsequent pregnancies. The recurrence rate will
depend upon the family history, environmental history, presence of
chromosomal abnormalities and co-existing syndromes. If the
hydrocephalus is X-linked then there is a 50% recurrence rate in males.
If the ventriculomegaly is isolated, then the recurrence rate is
approximately 4%.
Dr. Jayaprakash
Superintendent, ICH.
Institute of Child Health.
Gov. Medical College Kottayam.
Kerala, India.