Congenital Malformations of the Posterior Fossa: A Review of Clinical and Radiological Features Through an Illustrated Guide

Resumo

Congenital malformations of the posterior fossa (PF) encompass a wide spectrum of morphological anomalies that arise during embryonic development. This paper provides a narrative review of these most common disorders from a morphological approach based on the division into cystic (Dandy-Walker malformation, Blake’s Pouch cyst, mega cisterna magna, arachnoid cyst, and cerebellar vermis hypoplasia) and non-cystic malformations (Joubert syndrome, rhomboencephalosynapsis, and pontocerebellar hypoplasia). The embryogenesis of PF structures is briefly outlined. While magnetic resonance imaging is the preferred modality for evaluation, computerized tomography and ultrasonography serve complementary roles. In conjunction with clinical aspects, specific radiological features, such as cerebellar vermis morphology, Torcular Herophili position, and the presence/absence of mass effect, are highlighted for accurate diagnosis. We also present some typical radiological findings in non-cystic malformations, such as molar tooth sign, diamond-shaped fourth ventricle, and dragonfly-shaped cerebellum. This comprehensive review aims to assist radiologists, neuropediatricians, and general neurologists in recognizing and describing PF malformations, thereby facilitating appropriate management strategies.