Intermediate
Technical
In the Industry Vocabulary Test
Chiari malformation
Pronunciation: kee-AH-ree mal-for-MAY-shun
Congenital condition where cerebellar tissue extends below the skull into the spinal canal.
Full Definition
Chiari malformation is a structural defect in which cerebellar tissue protrudes through the foramen magnum into the upper spinal canal. Type I is the most common variant in adults, characterized by cerebellar tonsillar herniation greater than 5mm below the foramen magnum. This condition can cause symptoms including occipital headaches, neck pain, and neurological deficits. Treatment may require posterior fossa decompression surgery to relieve compression and restore normal cerebrospinal fluid flow.
Usage
Usage note: Specify the type (I, II, III, or IV) when documenting Chiari malformations.
In Context
- "MRI demonstrated Chiari malformation Type I with 8mm tonsillar descent." — radiology report
- "The patient underwent suboccipital craniectomy for symptomatic Chiari malformation." — operative summary
Also known as
Chiari I malformation
cerebellar tonsillar herniation
Contrasted with
normal posterior fossa anatomy
Don't confuse with
basilar invagination
syringomyelia