Fetal and perinatal neuroimaging of midbrain and hindbrain malformations

Midbrain and hindbrain malformations comprise a heterogeneous group of developmental disorders with overlapping clinical and imaging features that can pose diagnostic challenges in the fetal and perinatal periods. While some of these malformations are associated with favorable outcomes, others are indicative of poor viability. Accurate and comprehensive imaging evaluation is critical to guide prognostication and optimize perinatal management. This pictorial review illustrates the prenatal and postnatal imaging spectrum of these uncommon disorders and highlights characteristic findings that facilitate diagnosis and differentiation. Representative cases include diencephalic-mesencephalic junction dysplasia, Möbius sequence, rhombencephalosynapsis, microcephaly with disproportionate cerebellar and brainstem hypoplasia syndrome, Walker-Warburg syndrome, Joubert syndrome–related disorders, horizontal gaze palsy with progressive scoliosis, pontine tegmental cap dysplasia, medullary malformations, pontocerebellar hypoplasia, and cerebellar hemisphere hypoplasia, organized based on a previously proposed classification system.