SPECTRUM OF CNS AND EXTRA CNS FINDINGS IN COMMISURAL AGENESIS, A FETAL MRI STUDY

Abstract

<strong>Purpose:</strong> To categorize structural CNS and extra-CNS anomalies associated with abnormalities of the corpus callosum,.

<strong>Material and Methods:</strong> The university ethics committee approved this retrospective study. 821fetal MRI's were done during 2017-2018 in our institution, including 34corpus callosum and commissural anomalies. MRI's were done on a Seimens Avanto 1.5T Scanner and interpreted with prior knowledge of the mid trimester anatomical survey. Post-delivery follow-ups and images were obtained when available using patients phone numbers and national registry results.

<strong>Result:</strong> The MR imaging studies of 167 fetal suspected with ventriculomegaly with ultrasound were reviewed to evaluate types of abnormalities of the corpus callosum. MRI confirmed presence of ventriculomegaly in 94 cases. In 45 (47.8%) out of 94 cases with ventriculomegaly the anomaly of corpus callosum was the suspected in ultrasound. Complete corpus callosum agenesis in 19 Cases and partial agenesis of the corpus callosum in 11 cases were identified, and the remaining 15 Cases had normal corpus callosum. Additional abnormalities were also implemented in the reviewed cases, categorized in two groups as “extra CNS" and “additional CNS" abnormalities. Anterior commissure was seen in 15 cases of complete agenesis while hippocampal commissure was seen in only one. In complete CCA extra CNS abnormalities documented in 4cases consisted of Renal hypoplasia (1), pulmonary agenesis (1) lower extremimty palsy (1) and bilateral cleft lip (1). The additional CNS anomalies documented in 9 cases include; polymicrogyria (3), shallow insula (2), heterotopia (2) , cerebellar hypoplasia (2). In partial CCA, 1 case of extra CNS anomaly include bilateral cleft lip and palate (1) and 7 cases with additional CNS abnormalities documented constituted of; hydrocephaly(1), closed lip schizencephaly (1), polymicrogyria (2), septo optic dysplasia (2) , dandy walker malformation (1). In both groups all the extra-CNS findings had also been detected in ultrasound, while out of the extraCNS findings only the cerebellar hypoplasia was seen in ultrasound.

<strong>Conclusion:</strong> MRI can detect additional CNS anomalies in patients with ACC and can help rule out callosal agenesis with confidence. Given the heterogeneous clinical outcome of ACC, this can have prognostic and counseling value.