[Static-dynamic computerized tomography in the diagnosis of traumatic lesions of alar ligaments. Preliminary results]

The patients affected with cervical injuries often complain of cervical pain, headache and dizziness even when no bone fractures are detected. Such patients are likely to have a post-traumatic injury of the cervical ligaments. Twenty-five symptomatic patients (19 women and 6 men) were examined with upper spine CT and functional CT scans (right and left rotation) to detect ligament injuries and hypermotility of the craniocervical junction, both related to traumatic events. Eleven patients showed no alterations, while unilateral densitometric alterations of the alar ligaments were observed in 14 cases and thought to be related to trauma. On axial CT scans, the normal alar ligaments were identified as paramedian, quadrangular soft-tissue structures at the apex of the dens epistrophei and right above it. In 14 patients with alar ligament injuries, CT showed incomplete ligament interruption and thinning in 12 cases and its total absence on all images in 2 cases. The laterodental space in the affected side was hypodense due to fat tissue replacement. Of 14 patients with alar ligament injuries, only 14 patients with alar ligament injuries, only 4 exhibited rotatory hypermotility at C0-C1 and C1-C2. The low frequency of rotatory hypermotility is probably due to the high rate of incomplete alar ligament injuries as well as to cervical muscle stiffness, which is marked in some subjects. In conclusion, static and functional CT of the upper spine is not only useful to predict trauma outcome, but also allows the detection of the alar ligaments, of their morphodensitometric changes and of the segmental instability of the craniocervical junction.