Distinct Neuroimaging Perspective: Semi-Lobar Holoprosencephaly Through the Lens of MRA

Holoprosencephaly is a rare congenital brain malformation characterised by fused right and left cerebral hemispheres, midline and deep brain structures.Classically, it is of three types: lobar, semi-lobar, and alobar variety.It has a prevalence of 1 in 10,000-16,000 live births.While most of the literature focused on structural malformations, cerebrovascular anomalies got less attention.Emerging evidences suggest that vascular malformation accompanies the primary structural defect and helps in diagnosis and clinical management.The authors report a case of a 15-day girl presenting with enlarged head size, sunset phenomenon of eyes, and bulging fontanelle.MRI of the brain revealed the classic appearance of semi-lobar holoprosencephaly associated with congenital aqueductal stenosis and parietal encephalocele.Magnetic resonance angiogram (MRA) revealed paired internal carotid arteries, two separate anterior cerebral arteries, and the left middle cerebral artery up to the proximal M3 segment.The anterior communicating artery (A-com) and the right middle cerebral artery (MCA) were absent.Despite a normal vertebral-basilar artery, both posterior cerebral arteries (PCAs) were absent.This case highlights the rare anomalous vasculature associated with holoprosencephaly and adds to the limited existing literature on this subject.