Imaging description

Open mouth odontoid radiographs or cervical spine CT demonstrate asymmetric position of the dens between the lateral masses of C1 [1]. The C1 lateral mass contralateral to the direction of head rotation is subluxed anteriorly relative to the C2 lateral mass, while the ipsilateral C1 lateral mass might be posteriorly displaced. This asymmetry can be normal during head rotation, and is very frequently encountered on imaging. If, however, the asymmetric relationship persists when the head is then turned to the contralateral side, atlantoaxial rotatory fixation (AARF) is diagnosed.

Importance

At our institution, far more trauma patients are transferred from outside institutions for further evaluation for AARF than are ultimately diagnosed with it. Differentiation between AARF and acute torticollis, however, is important because torticollis responds to analgesics and conservative management, while AARF requires reduction. Furthermore, reduction has been more successful when performed early in the course of the condition.