Pediatric lateral atlantodental interval: how much asymmetry is normal?

Imaging of the cervical spine is commonly performed in the pediatric patient population, typically after trauma, as well as for a variety of nontraumatic reasons. There are many challenges in the interpretation of these studies, particularly at the level of the atlantoaxial joint. We recognized a particular problem with assessing the lateral atlantodental interval in our emergency radiology department. Mild lateral atlantodental interval asymmetry in relatively asymptomatic patients was being interpreted as indicative of atlantoaxial rotatory fixation, which leads to the recommendation for dynamic computed tomographic examinations. The goal of this study was to define the reference range of the lateral atlantodental interval in pediatric patients to help avoid misinterpretation of radiographic findings and resultant excessive imaging.