Five children who were at risk for atlanto-axial instability underwent
computerized tomography scanning of the cervical spine in flexion and
extension to document the degree of bone instability and the presence or
absence of spinal cord compression. Two patients had Morquio's syndrome,
two had os odontoideum , and one had Klippel-Feil syndrome, and in all five
the lateral radiographs of the cervical spine in flexion and extension were
equivocal with regard to instability or were difficult to interpret because
of the bone anomalies. The computerized tomography scan then provided a
diagnosis by a non-invasion technique and quantitated the amount of
compromise of the spinal cord by delineating flattening of the cord. The
scan therefore helped the surgeon to decide if the spinal cord was at
significant risk and if atlanto-axial fusion was advisable.