Female, 29 years old, currently approximately 24 weeks gestational age, with cerebellar splaying noted on sonography. The inferior aspect of the cerebellar vermis appears hypoplastic or absent and the superior aspect of the vermis may be mildly upwardly rotated. This gives the appearance of a widened inferior fourth ventricular outflow tract. The cerebellar hemispheres may be slightly splayed laterally.The vestigial point of the fourth ventricle is vaguely discerned which is normal for gestational age. The cerebellar hemispheres appear subjectively normal in size and the transverse cerebellar diameter is also within normal limits for gestational age. The retrocerebellar CSF space may be slightly prominent. The posterior fossa itself is of normal size and the torcular is normally positioned.The brainstem is within normal limits. The cerebellar hemispheres demonstrate normal morphology for gestational age. The corpus callosum is present. The supratentorial ventricles are not dilated. No focal parenchymal lesions are suspected. No intracranial hemorrhage or any abnormal extra-axial collection is suspected.
Relatively mild anomalous cerebellar morphology is seen including a hypoplastic or absent inferior vermis with slight upward vermian rotation. This gives the appearance of a widened inferior fourth ventricular outflow pathway.Findings are suggestive of partial vermian agenesis or a very mild manifestation of the Dandy-Walker continuum such as Blake pouch cyst. This appears to be an isolated anomaly as no other intracranial abnormalities are observed.