Ventriculomegaly, the commonest anomaly of the fetal brain, carries a mortality rate of 70% to 80%, and half of surviving children fail to develop normally. This poor outcome is related to the fact that two thirds of affected individuals have associated anomalies and 9% are aneuploid. The outlook is better for isolated mild ventriculography (IMV), defined by an atrial width of 10–15 mm. Currently available data suggests that only 15% of those with IMV die and a large majority of survivors develop normally. However, because IMV is a diagnosis of exclusion, many clinicians still do karyotype testing, targeted sonograms, and even fetal MRI to search for other abnormalities. To determine if this detailed evaluation is necessary and to confirm the prognosis of IMV, the authors carried out this retrospective study of 167 cases of IMV. Affected fetuses had unilateral or bilateral ventriculomegaly, with an atrial width of 10 to 15 mm, and no associated anomalies identified during the first sonogram. Two sonographers specializing in fetal brain disorders made the diagnosis. After excluding terminations, there were 146 live births, and psychomotor assessment was carried out in 101 children.
The median maternal age at the time IMV was diagnosed was 30 years, and the mean gestational age at diagnosis was 26.5 weeks. The ratio of male to female fetuses was 1.31. Ventriculomegaly was unilateral in 48% of cases, bilateral and symmetrical in 42%, and bilateral and asymmetrical in 10%. Amniocentesis identified four aneuploidies (two cases of Trisomy 21, one 47XXY, and one 47XYY). MR imaging, done at a mean gestational age of 33 weeks, revealed associated major brain anomalies in 12% and normal ventricles in 7% of cases. IMV remained stable in 55% of cases, regressed in 34%, and became worse in 11%. In 17% of cases, follow up sonography identified major intracerebral and extracerebral anomalies not previously seen. Sixteen pregnancies were terminated, and all these fetuses had additional anomalies.
At follow-up evaluation, done at a mean age of 4.5 years, twelve of 101 children had neurological disease or delayed psychomotor development. An atrial width of 12 mm or more at the time of the initial ultrasound examination and progressive ventricular enlargement (defined as an increase in ventriculomegaly of more than 3 mm) were correlated with a poor neurological outcome. Asymmetrical bilateral ventriculomegaly was also strongly associated with a poor outcome, with 50% having postnatal neurological disease, compared to only 7.5% of those with unilateral dilation and 10% with symmetrical ventriculomegaly. At the time of the initial ultrasound exam, 65 fetuses had nonprogressive unilateral or bilateral symmetrical ventriculography of less than 12 mm, and 61 of these (94%) had totally normal psychomotor development.