Basilar invagination
Basilar invagination is invagination of the base of the skull that occurs when the top of the C2 vertebra migrates upward. It can cause narrowing of the foramen magnum. It also may press on the lower brainstem.
This is similar to Chiari malformation. That, however, is usually present at birth.
Diagnosis
A doctor will base his or her diagnosis on the symptoms the patient has and the results of tests, including:- An X-ray
- Magnetic resonance imaging, which usually provides the most information
- Computed tomography scan