Forward displacement of the atlas on the axis is a comparatively rare condition, ordinarily treated by conservative methods. Operative intervention has been recorded in but few cases and only when pressure myelitis has developed. The more common unilateral or rotary dislocation will not be considered here, since it is a less serious lesion, with a far better prognosis, and ordinarily responds to the manipulative method of Walton.1
The condition we are considering is frequently immediately fatal. In cases in which death does not occur the diagnosis at first may be easily overlooked, since there is usually no evidence of spinal cord injury. The dislocation is ordinarily a progressive one the seriousness of which is attested only by increasing pressure myelitis or sudden death.
At the time of the original trauma, the common lesion is a fracture of the odontoid process at its base and loosening of the atlanto-axial ligaments
KAHN EA, YGLESIAS L. PROGRESSIVE ATLANTO-AXIAL DISLOCATION. JAMA. 1935;105(5):348-352. doi:10.1001/jama.1935.02760310022006