Chiari malformation

Chiari malformation is a developmental abnormality of the brain.

General

• Usually a radiologic diagnosis.
• May be seen in a fetal autopsy.

Classification

Numbered from least severe to most severe:

• Chiari type I - tonsils herniated (radiologic definition: 4-6 mm below the plane of the foramen magnum).
  • Associated with: sudden death, sleep apnea, cerebellar ataxia.
• Chiari type II - often assoc. with hydrocephaly at birth.
• Chiari type III - cerebellum + brain stem herniate through foramen magnum +/- encephalocele.
• Chiari type IV - cerebellar hypoplasia or no cerebellum.

See also

• Fetal autopsy.
• Neuropathology.