Which hindbrain malformation is classically associated with myelomeningocele?

Which hindbrain malformation is classically associated with myelomeningocele?

• A. Chiari I malformation
• B. Chiari II malformation
• C. Dandy-Walker malformation
• D. Arnold-Chiari III malformation

Answer: (C)

The link between a spinal neural tube defect like myelomeningocele and hindbrain malformations is most classically seen with Chiari II malformation. In this condition, the brainstem and cerebellar vermis herniate downward through the foramen magnum, often accompanied by a small posterior fossa and hydrocephalus from aqueductal stenosis. This pattern arises from disrupted CSF dynamics and abnormal neural development associated with the spinal defect. Dandy-Walker malformation, by contrast, features a cystic dilation of the fourth ventricle and hypoplasia of the cerebellar vermis in the posterior fossa and is not the typical partner with myelomeningocele. Other forms of Chiari have different clinical contexts and are not the classic association here.

The link between a spinal neural tube defect like myelomeningocele and hindbrain malformations is most classically seen with Chiari II malformation. In this condition, the brainstem and cerebellar vermis herniate downward through the foramen magnum, often accompanied by a small posterior fossa and hydrocephalus from aqueductal stenosis. This pattern arises from disrupted CSF dynamics and abnormal neural development associated with the spinal defect. Dandy-Walker malformation, by contrast, features a cystic dilation of the fourth ventricle and hypoplasia of the cerebellar vermis in the posterior fossa and is not the typical partner with myelomeningocele. Other forms of Chiari have different clinical contexts and are not the classic association here.