Asymmetry of the Odontoid Lateral Mass Interval in Pediatric Trauma CT: Do We Need to Investigate Further?

BACKGROUND AND PURPOSE Odontoid lateral mass interval asymmetry can be within the normal spectrum or the result of traumatic atlantoaxial injury. We sought to set radiographic guidelines for further investigation of odontoid lateral mass interval asymmetry in cervical spine CT studies of pediatric trauma patients. MATERIALS AND METHODS Fourteen children with C1-2 ligamentous injury or atlantoaxial rotational fixation/subluxation were retrospectively identified. We identified an additional 56 children fulfilling the following inclusion criteria: 1) They underwent C-spine CT to exclude traumatic injury, and 2) C-spine clearance and follow-up. Those were matched for age, sex, and severity of traumatic insult with the injured group. Clinical data were collected, and we measured the following parameters: anterior atlantodental interval; odontoid lateral mass interval; and the rotation of the head, C1, and C2. RESULTS A significant difference (P < .001) was found between the groups in cervical tenderness and torticollis. There was a significant difference in the atlantodental interval value (3.3 ± 0.8 mm in injured and 2.2 ± 0.5 mm in noninjured). The directionality of head, C1, and C2 rotation was significantly (P < .05) more toward the same direction in the noninjured group. We found significant linear correlation between head rotation and ipsilateral odontoid lateral mass interval asymmetry only in the noninjured at C1-2. With multivariant analysis, the presence of cervical tenderness and an abnormal atlantodental interval were the most significant variables. CONCLUSIONS Odontoid lateral mass interspace asymmetry in the absence of cervical tenderness and with a normal atlantodental interval is likely in the normal range and need not be further investigated.