The Fetal Cerebellar Vermis

Abstract

Fetal magnetic resonance provides a new tool in the imaging of the posterior fossa and is proving useful in cases that are difficult to assess sonographically by allowing further assessment of the fourth ventricle, cisterna magna, and vermian growth and development. We describe various criteria with which to evaluate vermian growth, including vermian biometry and the relationship between the superior and inferior lobes. We demonstrate 2 markers of normal vermian development: the primary fissure and fastigial point. We illustrate the tegmento-vermian angle, "closure" of the fourth ventricle, and communication of the fourth ventricle with the basal cisterns during development and in several disorders. We correlate those features with the expected embryological course of development and illustrate identification of these features and associated abnormalities of the posterior fossa, brain stem, and central nervous system in mid-trimester scans of fetuses with abnormal development. Correlation with contemporaneous ultrasound examinations is demonstrated.

Refining the Neuroimaging Definition of the Dandy-Walker Phenotype

“…The growth and development of the posterior vermis are the most protracted of all regions, making it especially vulnerable to disruptive events. 10,11,21 The inferior vermis is the most common and most severely involved region in DWM and isolated vermian hypogenesis, ie, partial agenesis. 11 Nonetheless, inferior VH should be diagnosed only if it can be documented that the inferior vermis is small.…”

Development of the Fetal Vermis: New Biometry Reference Data and Comparison of 3 Diagnostic Modalities-3D Ultrasound, 2D Ultrasound, and MR Imaging

“…Moreover, there were no comparisons among all 3 imaging modalities. 20 The aims of our study were the following: to provide normal reference biometric data of the fetal vermis in 4 biometric parameters for 3 imaging modalities, to evaluate the reproducibility of the vermian biometry, and to compare the measurements obtained by 2D sonography, 3D sonography, and MR imaging.…”

Fetal and postnatal MRI findings of Blake pouch remnant causing obstructive hydrocephalus

“…The vermis size measured by largest height and anterior-posterior (AP) dimensions, parallel and perpendicular to the axis of the ventral vermis, respectively, should also be routinely measured and compared to normal values. Superior and inferior vermis height proportions can also be evaluated on either side of the AP dimension or fastigial point-declive line, with the height of the inferior vermis being about equal to or slightly more than the superior vermis [3] . Finally, vermian lobulation can be assessed with all major lobules visible by 27 weeks GA.…”