Fig. 1

A Pre-operative lateral X-ray of the cervical spine demonstrating the classic “sandwich fusion” of both C0-1 and C2-3 and atlantoaxial dislocation. B Pre-operative sagittal reconstruction of MRI of the cervical spine demonstrating basilar invagination as well as anterior compression of the medulla by the cranially migrated odontoid tip. There was also significant syringomyelia. C Post-operative lateral X-ray of the cervical spine at the one-year follow-up demonstrating maintenance of reduction of atlantoaxial dislocation by occipito-cervical fixation consisting of six occipital screws, two C2 pedicle screws, and two C3 lateral mass screws