Prenatal and Postnatal Follow-Up of a Fetal Interhemispheric Arachnoid Cyst with Partial Corpus Callosum Agenesis, Asymmetric Ventriculomegaly and Localized Polymicrogyria

Abstract

We report a case of a fetal interhemispheric arachnoid cyst associated with partial callosal agenesis and asymmetric ventriculomegaly. After second trimester ultrasound diagnosis and evaluation, magnetic resonance imaging (MRI) at 28 weeks showed polymicrogyria laterally to the cyst. The parents decided to continue the pregnancy. The diagnosis was confirmed after birth by transfontanellar ultrasound examination and MRI. In the neonatal period, the child was sleepy and showed axial hypotonia. At 1 month of age, he had a normal neurological examination. Cyst-peritoneal shunting was performed at 5 weeks of age because the cyst increased markedly in size, and shunt revision was required at 8 months of age. At 17 months, he had mild left-side hemiparesis but he could walk alone and had begun to speak. To date, the child never experienced seizures. We review other published cases and discuss the postnatal outcome of this rare association.

Agenesis of the corpus callosum with interhemispheric cyst, associated with aberrant cortical sulci and without underlying cortical dysplasia

“…In such cases prenatal counseling is crucial, and careful analysis of cerebral organization is required, in particular to look for gyration using MRI 2,3 . In our two cases, abnormal focal cortical anomalies on the inner border on one hemisphere adjacent to the cyst were suggestive of focal polymicrogyria, previously reported as one of the most frequent anomalies associated with IHC 4,5 . This association correlates with an increased risk for hemiparesis and epilepsy 5 , which led to the termination of pregnancy in our cases.…”

“…In our two cases, abnormal focal cortical anomalies on the inner border on one hemisphere adjacent to the cyst were suggestive of focal polymicrogyria, previously reported as one of the most frequent anomalies associated with IHC 4,5 . This association correlates with an increased risk for hemiparesis and epilepsy 5 , which led to the termination of pregnancy in our cases. Interestingly, although macroscopic examination confirmed the imaging data, the cortex was histologically normal.…”

Prenatal diagnosis and outcome of partial agenesis and hypoplasia of the corpus callosum

“…Whether callosal partial agenesis represents a true malformation or is the consequence of a disruptive event is uncertain 6 . An association with interhemispheric arachnoid cyst, holoprosencephaly, asymmetric ventriculomegaly and migration disorders is reported 19,20 . Prenatal diagnosis of fetal callosal underdevelopment remains a difficult task with only few cases of partial agenesis reported in the literature 10,11,20,21 .…”

Main Congenital Cerebral Anomalies: How Prenatal Imaging Aids Counseling

“…Children presenting with these malformations have usually a normal neurodevelopmental outcome. However, late-onset epilepsy can occur in large interhemispheric cysts (related to polymicrogyria lining the cyst) [15] or in tubulonodular lipomas.…”