Chiari malformation
Structural cerebellar defect causing brainstem compression and varied neurological symptoms.
Chiari malformation (CM) is a structural defect in the cerebellum, characterized by downward displacement of one or both cerebellar tonsils through the foramen magnum. It is named after Austrian pathologist Hans Chiari, who described related hindbrain anomalies in the late 19th century. The condition can cause a range of neurological symptoms, including headaches, difficulty swallowing, dizziness, and in severe cases, paralysis.
- field
- Neurology
- named_after
- Hans Chiari (Austrian pathologist)
- also_known_as
- Arnold–Chiari malformation (type II)
- classification
- Types I–IV, with additional subtypes Chiari 0, 1.5, 3.5, and 5
- common_symptom
- Headache, often occipital and aggravated by Valsalva maneuvers
- diagnostic_tool
- Magnetic resonance imaging (MRI)
Lore & Background
Hans Chiari, an Austrian pathologist, first described the malformations that bear his name in the late 19th century, categorizing them as types I, II, and III. Later investigators added a type IV. The type II malformation is also called Arnold–Chiari malformation, after Chiari and German pathologist Julius Arnold. The condition involves herniation of cerebellar tonsils through the foramen magnum, often due to a congenitally small posterior fossa or increased intracranial pressure.
Reader's Guide
Chiari malformation is significant as a common cause of headache, brainstem dysfunction, and syringomyelia. Its pathophysiology includes congenital small posterior fossa, hydrocephalus, or negative pressure from tethered cord or CSF leak. Diagnosis relies on MRI, with tonsillar displacement greater than 5 mm often considered abnormal. The condition can present in childhood with rapid neurological decline or in adulthood with more subtle symptoms. Syringomyelia occurs in 25% of type I cases. Treatment focuses on decompression, but the article does not detail management. The legacy of Chiari and Arnold endures in the classification and understanding of hindbrain herniation syndromes.
Did You Know?
- Chiari malformation is named after Austrian pathologist Hans Chiari.
- Type II CM is also known as Arnold–Chiari malformation after Chiari and German pathologist Julius Arnold.
- Headache is the most common symptom, typically occipital and aggravated by Valsalva maneuvers.
- Syringomyelia is present in 25% of patients with type I Chiari malformation.
More in Diseases named after discoverers 1-24
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