First trimester three-dimensional ultrasound diagnosis of iniencephaly. A case report with review of literature

Abstract

Iniencephaly is a rare neural tube defect, characterized by the classical triad of extreme retroflexion of the head, occipital bone defect and variable rachischisis. Its etiology is not fully understood: it might arise due to anomalies of genes controlling the planar cell polarity pathway, affecting the dorso-ventral orientation of the body axis. Risk factors include low socio-economic status and lack of folic acid supplementation. In up to 90% of cases involves female gender. We report a case diagnosed prenatally at 13 weeks by ultrasonography. It was characterized by abnormal shape of the fetus, with no distinct separation between the head and the body, extreme retroflexion of the fetal head, significant shortening of the spine, hypotelorism and holoprosencephaly. Three-dimensional (3D) ultrasound reconstruction evidenced the occiput absence and the same marked retroflexion with lordotic cervical spine, but with clear, distinct, un-fussed vertebrae. The parents opted to have an elective termination of pregnancy. Pathological examination confirmed the diagnosis, showing a perfect correlation with the ultrasound findings. The anomaly is incompatible with life, and early antenatal ultrasound diagnosis is advisable. Suggestive 3D images were helpful for illustrating these issues to the parents during prenatal counseling.