Contribution of Fetal MRI in the Antenatal Diagnosis of Alobar Holoprosencephaly: A Case Report

Abstract

Introduction: Holoprosencephaly is a rare cerebral malformation, of multiple etiologies and often associated with other malformations, particularly facial. It results from a defect in the early development of the prosencephalon. The fetal prognosis is extremely poor, especially in the alobar form. Objective: The aim of this work is to illustrate through this observation the contribution of fetal MRI in the antenatal diagnosis of this rare and serious pathology. Case Report: We report the case of a 26-year-old primigravida and primiparous parturient referred for suspected agenesis of the vermis and corpus callosum following a first ultrasound performed in the third trimester of pregnancy. The pregnancy was not followed up and the date of last menstrual period was unknown. A fetal MRI was performed showing: A mono-fetal pregnancy in cephalic presentation with fundial placenta, A single ventricle with posterior cystic expansion and laminated aspect of the cerebral parenchyma at the frontal level, A bilateral pyelo ureteral junction syndrome. Conclusion: Alobar holoprosencephaly is a rare and fatal pathology with a great etiological heterogeneity. It can be part of a polymalformative syndrome. It results from a cleavage anomaly of the prosencephalon into cerebral hemispheres. The antenatal diagnosis is based on obstetrical ultrasound completed by fetal MRI allowing an exhaustive lesion assessment of this pathology with an extremely reserved prognosis.