Summary of VA anomalies in 12 patients with occipitalization of the atlas.
| Case No. | Fusion Type | Morphology of the VA | Hypoplastic Side of the Transverse Foramen | Course of the V3 Segment of the VA into the Cranium |
|---|---|---|---|---|
| 1 | partial | rt, hypoplasia | both sides: extraspinal canal | |
| 2 | complete | rt, hypoplasia | both sides: extraspinal canal | |
| 3 | partial | no laterality | both sides: normal | |
| 4 | complete | rt, agenesis | rt | lt: intraspinal canal under the atlas |
| 5 | complete | lt, agenesis | lt | rt: extraspinal canal |
| 6 | complete | rt, hypoplasia | both sides: extraspinal canal | |
| 7 | partial | lt, agenesis | lt | rt: normal |
| 8 | complete | no laterality | rt: extraspinal canal lt: intraspinal canal under the atlas | |
| 9 | complete | rt, hypoplasia | both sides: extraspinal canal | |
| 10 | partial | rt, agenesis | rt | lt: normal |
| 11 | complete | rt, hypoplasia | both sides: extraspinal canal | |
| 12 | complete | rt, hypoplasia | rt | both sides: extraspinal canal |