Inferior vermian hypoplasia – preconception, misconception

Diagnostic Value of Prenatal MR Imaging in the Detection of Brain Malformations in Fetuses before the 26th Week of Gestational Age

“…In such cases, the vermian rotation was isolated and of mild-to-moderate range (Ͻ25°), with a normal-sized posterior fossa and normal tentorial insertion and vermian dimensions, thus suggesting a persistent Blake pouch cyst. 25 Sometimes the Blake pouch cyst disappears by the third trimester due to late fenestration, and the cranial vermian rotation could be detected only until 24 -26 weeks. Therefore, isolated mild-to-moderate vermian rotation detected at an early GA does not necessarily indicate an adverse outcome, and in onethird of cases, it undergoes spontaneous resolution in utero, 25 explaining our false-positive findings.…”

“…25 Sometimes the Blake pouch cyst disappears by the third trimester due to late fenestration, and the cranial vermian rotation could be detected only until 24 -26 weeks. Therefore, isolated mild-to-moderate vermian rotation detected at an early GA does not necessarily indicate an adverse outcome, and in onethird of cases, it undergoes spontaneous resolution in utero, 25 explaining our false-positive findings. However, even if less common, vermian rotation is reported to be associated with other anomalies in up to 25% of cases, and in Ͻ10% of survivors, it is associated with abnormal postnatal neurologic development, 26 thus giving reason to include it among our prenatal MR imaging findings.…”

Three-dimensional neurosonography — a novel field in fetal medicine

“…Measurement of cisterna magna between 2-11 mm and atrial width of the lateral ventricles < 10 mm have very high negative, predictive value for the detection of brain abnormalities [13,14]. Using those two criteria, the majority of CNS defects may be excluded.…”

“…Noteworthy, the theory published by Robinson et al, regarding the development of the posterior fossa, may shed some light on the current state of knowledge and approach to certain abnormalities. These authors suggest that there might be a continuum in posterior fossa anomalies involving the fourth ventricle and the Blake's pouch [14].…”

Diagnostic imaging of posterior fossa anomalies in the fetus and neonate: Part 1, normal anatomy and classification of anomalies

“…In recent years, there have been changes in the terminology used and the description and mechanisms of the different entities, and therefore literature about this topic can be somewhat confusing [6,7]. It is essential to determine the type of posterior fossa malformation as accurately as possible, as it reflects the postnatal outcome and may guide efforts at detection of associated anomalies, both within and outside the CNS.…”