Chiari II Malformation

Summary

Chiari II malformations are a type of malformation in the posterior fossa of the brain. It involves the downward displacement of both the medulla and the cerebellum. This severe anatomical displacement can block CSF outflow to cause non-communicating hydrocephalus. Cases of Chiari II malformations are commonly seen early in childhood, and are associated with myelomeningocele. Patients may present with cerebellar symptoms like severe ataxia, medullary symptoms like vomiting, as well as headaches.

Key Points

• Chiari II malformation
  • Type of posterior fossa malformation
  • Pathophysiology
    • Downward displacement (herniation) of cerebellum (vermis and tonsils) and medulla through foramen magnum
    • Causes non-communicating hydrocephalus
    • Associated with
      • lumbosacral myelomeningocele
  • Presentation
    • Seen in children
    • Cerebellar symptoms (severe ataxia)
    • Medullary symptoms
    • Headaches