Findings are suggestive of Arnold Chiari malformation type II associated with corpus callosum dysgenesis and severe ventriculomegaly.

MRI is the modality of choice for detecting and characterizing the full constellation of findings associated with Chiari II malformation. The key features are myelomeningocele (lumbosacral spina bifida aperta) and a small posterior fossa with descended brainstem and cerebellar tonsils. Numerous associated abnormalities are also frequently encountered.