Instability of the upper cervical spine in Down syndrome.

This study of 64 Down syndrome children at British Columbia's Children's Hospital established that ligamentous laxity of the upper cervical spine may exist at more than one location. Instability at the atlantooccipital level is common and must be considered along with the previously documented atlantoaxial instability. Treatment should depend on room available for the spinal cord instead of absolute values of displacement.