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MRI is unnecessary to clear the cervical spine in obtunded/comatose trauma patients: the four-year experience of a level I trauma center.

BACKGROUND
Cervical (C)-spine clearance protocols exist both to identify traumatic injury and to expedite rigid collar removal. Computed tomography (CT) of the C-spine in trauma patients facilitates the removal of immobilization collars in patients who are neurologically intact, and magnetic resonance imaging (MRI) has become an indispensable adjunct for evaluating trauma patients with neurologic deficits. Yet, the management of patients with impaired mental status who lack neurologic deficits attributable to the spinal cord remains controversial. C-spine MRI has been suggested and employed as an imaging modality to exclude occult C-spine instability in this population of patients. However, currently available data are inconclusive as to the necessity of MRI in the C-spine clearance of obtunded or comatose trauma patients with a normal CT.


METHODS
The records of patients undergoing contemporaneous CT and MRI of the C-spine in a level I trauma center from January 2003 to December 2006 were retrospectively analyzed. From this group, patients admitted with a Glasgow Coma Scale score </=13 and a normal C-spine CT with sagittal and coronal reconstructions were identified. Patients were excluded if a neurologic deficit potentially referable to the spinal cord was identified. The results of C-spine MRI in this group were tabulated and analyzed.


RESULTS
A total of 690 patients were identified who had undergone contemporaneous C-spine CT and MRI. Of this group, 180 patients (26.2%) were identified as having a normal CT with sagittal and coronal reconstructions, no neurologic deficit, and Glasgow Coma Scale score </=13. Within this group, the average time interval between CT and MRI was 4.6 days (median, 4 days). Among these 180 patients, C-spine MRI identified 38 patients (21.1%) with acute traumatic findings in the cervical spine. However, none of these patients had a missed unstable injury and no patient required surgery or developed evidence of delayed instability.


CONCLUSION
Our data suggests that, outside of its appropriate application to patients with a neurologic deficit, MRI is unlikely to uncover unstable C-spine injuries in patients who are obtunded or comatose when C-spine CT using modern imaging protocols is normal.