atlantoaxial instability
Pronunciation: at-LAN-toe-AK-see-al in-sta-BIL-i-tee
Abnormal movement between the first and second cervical vertebrae (C1-C2), often requiring surgical stabilization.
Full Definition
Atlantoaxial instability refers to excessive mobility or displacement between the atlas (C1) and axis (C2) vertebrae at the craniovertebral junction. This condition can result from congenital abnormalities, trauma, inflammatory conditions, or degenerative changes. The instability may compress the spinal cord or brainstem, potentially causing neurological deficits. Surgical treatment typically involves posterior fusion with instrumentation to stabilize the atlantoaxial joint.
Usage
Usage note: Always hyphenate when used as a compound adjective; distinguish from atlanto-occipital instability which involves C0-C1.
In Context
- "The patient presented with atlantoaxial instability secondary to rheumatoid arthritis." — surgical consultation note
- "MRI demonstrated significant atlantoaxial instability with cord compression at the C1-C2 level." — radiology report