OC05.03: Malformations of cortical development: early prenatal ultrasound diagnosis

Although abnormal neurodevelopmental events leading to malformations of cortical development (MCD) occur during the 2nd and 3rd trimesters and usually remain undetected until close to or after delivery in some cases they can be demonstrated earlier. The purpose of this study is to describe sonographic findings diagnostic or highly suggestive of MCDs, which may be identified before the 24th week. This retrospective study enrolled fetuses referred between 2007–2016, with suspected MCD diagnosed early in mid-trimester and confirmed by postmortem evaluation or postnatal imaging and genetic studies. The patients underwent fetal neurosonography and morphological evaluation. Stored files were analysed for demographic data, abnormal brain findings, morphologic abnormalities, final prenatal diagnosis and outcome. Forty-three fetuses were included at a mean gestational age of 21w2d (range 14w5d-24w6d). The reasons for referral were MCD (23); callosal anomalies (CA) (17) and ventriculomegaly (3). US demonstrated signs of heterotopia (19); overdeveloped sulcation with and without CA (15,2, respectively); lissencephaly (9); hemimegalencephaly (4); abnormal cortex (4); schizencephaly (3); macrocephaly (2) and microcephaly (1). Associated CNS anomalies were detected in 35 and non-CNS malformations in 9; 2 cases were recurrent. 34 pregnancies were terminated and 9 fetuses were liveborn. Early diagnosis sonographic diagnosis of MCD is possible, probably representative of the most severe cases. Callosal anomalies, the presence of an abnormal ventricular wall and abnormal overdeveloped sulci appear to be early signs of MCD. Familiarity with fetal brain anatomy and its early sonographic landmarks allows for early diagnosis of a significant proportion of MCD.