In Down syndrome, up to what percentage have occipito-atlantal hypermobility?

In Down syndrome, up to what percentage have occipito-atlantal hypermobility?

• A. 40%
• B. 61%
• C. 20%
• D. 75%

Answer: (B)

The key idea is that the craniovertebral junction tends to be unusually lax in Down syndrome, so the occipito-atlantal joint often shows increased mobility. Because of this ligamentous laxity, a substantial portion of individuals with Down syndrome have some degree of occipito-atlantal hypermobility on dynamic imaging, and the best estimate reported is about 61%. This relatively high prevalence helps explain why clinicians are particularly attentive to neck stability in Down syndrome, especially before procedures that involve neck positioning or in cases with neurologic symptoms. The other percentages are less representative across typical patient populations, whereas 61% aligns with the common finding of notable but not universal hypermobility at this joint.

The key idea is that the craniovertebral junction tends to be unusually lax in Down syndrome, so the occipito-atlantal joint often shows increased mobility. Because of this ligamentous laxity, a substantial portion of individuals with Down syndrome have some degree of occipito-atlantal hypermobility on dynamic imaging, and the best estimate reported is about 61%. This relatively high prevalence helps explain why clinicians are particularly attentive to neck stability in Down syndrome, especially before procedures that involve neck positioning or in cases with neurologic symptoms. The other percentages are less representative across typical patient populations, whereas 61% aligns with the common finding of notable but not universal hypermobility at this joint.