Which statement best describes the prevalence of symptoms in atlantoaxial instability among children with Down syndrome?

• A. Most are asymptomatic
• B. Most are symptomatic
• C. Some are asymptomatic
• D. None are symptomatic

Answer: (A)

In Down syndrome, the laxity of the ligaments around the upper cervical spine makes atlantoaxial instability relatively common on imaging, but this does not usually produce symptoms. The spinal cord and brainstem can tolerate a fair amount of instability, so many children have radiographic signs without neurological problems. Only a small subset develops symptoms after significant subluxation or trauma, so the usual clinical picture is that most individuals are asymptomatic. This is why radiographic instability can be present without a need for urgent intervention unless new or progressive neurologic signs appear.