Prenatal diagnosis of posterior fossa anomalies--an overview.

Ultrasonography of the central nervous system is an integral part of a prenatal scan, and the development of imaging technologies has led to better diagnostic possibilities. Posterior fossa anomalies have traditionally been divided into Dandy Walke malformation, Dandy Walker variation and megacisterna magna, but this approach, due to diversity of the extensive number of possible disorders covered by this classification, unables accurate prognosis and therefore adequate counselling. An alternative approach to the classification of posterior fossa anomalies is to divide them into agenesis of the vermis, which could be partial or complete, cerebellar hypoplasia, pontocerebellar hypoplasia and cerebellar atrophy. Different ultrasonographic and magnetic resonance imagining of appearances of the posterior fossa anomalies in prenatal period are discussed in the article, as well as possible syndromes and prognosis of different entities. Diversity of anomalies of the central nervous system, and in particular, subtle differences in prenatal appearances of posterior fossa anomalies, which may have major impact on the prognosis, demand a multidisciplinary approach that encompasses two-dimensional and three-dimensional ultrasound scan, magnetic resonance imaging, infectious diseases and metabolic disorders work-ups as well as individual approach to every case involving of a team of experts in the field of perinatology, radiology, paediatrics, neurology and genetics.