Postnatal Intracranial Findings Following Fetal Repair of Spinal Dysraphisms

OBJECTIVE: Our objective is to document the imaging appearance in the intracranial compartment at the time of the infants' first postnatal brain MR imaging after fetal repair for spinal dysraphisms. METHODS: Twenty-nine patients were evaluated on fetal and postnatal magnetic resonance imaging for a series of features of Chiari II malformation. RESULTS: Of the 29 infants, 55% had resolution of tonsillar ectopia, and 62% showed a dorsal outpouching of the near the foramen magnum on postnatal magnetic resonance imaging. The majority had persistence of Chiari II features including: prominent massa intermedia (93%), tectal beaking (93%), towering cerebellum (55%), flattening of the fourth ventricle (90%), hypoplastic tentorium (97%), and tonsillar hypoplasia (59%). CONCLUSIONS: Normally positioned or minimally descended, oftentimes hypoplastic tonsils in the presence of a posterior fossa configuration typical of Chiari II, was the most common presentation. An additional documented feature was an outpouching of the dorsal thecal sac between the opisthion and the posterior arch of C1.