EP01.06: Isolated absence of septum pellucidum: a report of two cases

Abstract

Agenesis of the septum pellucidum (ASP) is a rare cerebral anomaly which can appear in a partial or a complete form and agenesis may occur in an isolated or in an association with various congenital brain malformations. We report two cases with isolated agenesis of septum pellucidum which were suspected prenatally with 2D ultrasound and fetal MRI. A-32-year-old G1P0 woman first visited Cheil General Hospital at 12weeks of gestation. During routine antenatal examination in 28 gestational weeks, CSP was not seen and the fusion between the frontal horns of lateral ventricle in fetal brain was found. Cerebral developmental anomalies related to the ASP were suspected. Fetal MRI was performed at 29 weeks and 4 days of gestation. Septum pellucidum was still not seen but the corpus callosum and the fornix were intact and no definite fusion in brain parenchyme was found. Due to fetal movement, measurement of the optic nerves were not possible. As a result, isolated ASP was suspected with possibility of septo-optic dysplasia. A full-term 3,245 gram female was born after a normal delivery. Postnatal evaluation with brain ultrasound was performed 3 days after birth and isolated ASP was suspected. The newborn was discharged afterward and no definite sign of focal neurologic deficit was found by this time. A-37-year-old G1P0 woman was referred at 17 weeks and 6 days of gestation due to increased risk of Trisomy 21 and neural tube defect in Quad test. Fetal karyotype was normal. In the mid-trimester ultrasound, estimated fetal weight was 3 percentile and small cystic lesion in fetal head posterior fossa was noted. She was hospitalised at 27 weeks due to symptoms of pre-eclampsia. In follow up ultrasound at 32 weeks and 1 day of gestation, estimated fetal weight was below 1 percentile and cystic lesion in posterior fetal head was still seen. The day after Caesarean section was performed due to fetal distress. A preterm 1,220 gram male was born. Brain ultrasound and MRI was performed 48 days after birth and isolated ASP with well visualised both optic nerves were noticed.