Chiari II refers to which phenomenon in spina bifida?

Chiari II refers to which phenomenon in spina bifida?

• A. Hindbrain herniation
• B. A type of heart defect
• C. A metabolic disorder
• D. A placental abnormality

Answer: (A)

Chiari II malformation is the hindbrain herniation that occurs with spina bifida. In this condition, parts of the hindbrain—the cerebellar tissue and brainstem—are pushed downward through the foramen magnum. This downward displacement is tied to altered CSF dynamics and a crowded posterior fossa, and it often comes with hydrocephalus from aqueductal stenosis. This makes hindbrain herniation the hallmark of Chiari II, setting it apart from other issues like heart defects, metabolic problems, or placental abnormalities.

Chiari II malformation is the hindbrain herniation that occurs with spina bifida. In this condition, parts of the hindbrain—the cerebellar tissue and brainstem—are pushed downward through the foramen magnum. This downward displacement is tied to altered CSF dynamics and a crowded posterior fossa, and it often comes with hydrocephalus from aqueductal stenosis. This makes hindbrain herniation the hallmark of Chiari II, setting it apart from other issues like heart defects, metabolic problems, or placental abnormalities.