A Case Report of Alobar Holoprosencephaly: the Role of Ultrasonographic Imaging

Abstract

Holoprosencephaly is a rare congenital brain malformation caused by the incomplete separation of the embryonic forebrain (prosencephalon), leading to a spectrum of cerebral and facial anomalies. The condition is classified into four types: alobar, semi-lobar, lobar, and middle interhemispheric fusion, with alobar HPE being the most severe, characterized by a lack of midline structures and a single ventricle. While the exact incidence is unclear, holoprosencephaly is associated with high mortality rates, particularly in its severe forms. Early prenatal diagnosis is crucial for guiding obstetric management, with sonography being a key diagnostic tool.  A 41-year-old G3P2A0 woman was referred to our fetomaternal clinic at 32 weeks of gestation with a suspected fetal anomaly. Ultrasound examination revealed findings consistent with alobar holoprosencephaly, including fused thalami, a single ventricle, absence of the cavum septum pellucidum, and facial anomalies such as cyclopia and proboscis. Despite a normal obstetric history and the absence of risk factors such as teratogenic exposure, the severity of the condition led to the decision to terminate the pregnancy. The patient delivered a male infant with an APGAR score of 3/4, weighing 1600 grams, who exhibited all the sonographic findings. The infant did not survive post-delivery. Alobar holoprosencephaly represents the most severe form of holoprosencephaly, associated with a poor prognosis and high perinatal mortality. Prenatal ultrasonography is essential for early diagnosis, allowing for informed decision-making regarding pregnancy management. Early termination may be considered to prevent maternal trauma, given the condition's uniformly fatal outcome.