Prenatal Diagnosis of Atretic Cephalocele: Ultrasound Demonstration of Superior Sagittal Sinus Fenestration and Fibrous Stalk, and Potential Role of Brainstem-Tentorium Angle.

We present two cases highlighting novel prenatal ultrasound findings in atretic cephalocele (AC) using high-resolution ultrasound and microvascular flow imaging. This report includes the first prenatal ultrasound demonstration of key diagnostic AC features: superior sagittal sinus fenestration, observed in the parietal case, and a fibrous dural stalk, identified in both parietal and occipital cases. Both fetuses presented with a small midline scalp lesion, internal echoes, and an underlying bony defect without brain tissue herniation. Additionally, an increased brainstem-tentorium angle was measured in both, suggesting its potential utility as a supportive diagnostic marker. We propose a refined two-tiered diagnostic framework to improve the accuracy of prenatal AC diagnosis and distinguish AC from true encephaloceles, facilitating appropriate parental counseling.