chiari malformation
Pronunciation: key-ARE-ee
A structural defect where brain tissue extends into the spinal canal due to skull abnormality or smaller than normal skull size.
Full Definition
A group of structural defects affecting the cerebellum, brainstem, and upper spinal cord. Type I Chiari malformation involves herniation of cerebellar tonsils through the foramen magnum, while Type II (Arnold-Chiari) is more severe with additional brainstem displacement and is typically associated with spina bifida. Symptoms may include headaches, neck pain, balance problems, and in severe cases, breathing or swallowing difficulties. Treatment may require surgical decompression to create more space for the brain and restore normal cerebrospinal fluid flow.
Usage
Usage note: Capitalize 'Chiari' as it is an eponym; specify type when known (Type I, II, etc.).
In Context
- "The MRI revealed a Type I Chiari malformation with 8mm tonsillar herniation below the foramen magnum." — Imaging report
- "Posterior fossa decompression was recommended for the symptomatic Chiari malformation causing recurrent headaches." — Surgical consultation note