High-quality CT is adequate for clearing c-collar in obtunded patients.
A follow-up exam before discharging the patient strengthens your decision making and documentation.
MRI can be reserved for high-risk patients, patients who are being admitted to surgical critical care units, and those who have residual findings once alert.
Many ED practitioners are not comfortable clearing the C-spine of mentally altered patients even after a negative high-quality CT scan. In 2015, the Eastern Association for the Surgery of Trauma (EAST) published an article that addresses this issue. The authors’ conclusion is summarized as follows: "In obtunded adult blunt trauma patients, we conditionally recommend cervical collar removal after a negative high-quality C-spine CT scan result alone. This conditional recommendation is based on very low-quality evidence but places a strong emphasis on the high negative predictive value of high-quality CT imaging in excluding the critically important unstable C-spine injury.” They went on to point out that adjunctive imaging after CT increases the number of low-value diagnoses, increases the possibility of unnecessary treatment plans, and increases risks for injured patients during transport to the imaging suite. However, they acknowledged that this approach could result in neurologic deterioration in some patients.
In 2016, the Western Trauma Association published the results of a prospective observational study that evaluated patients who did not meet the NEXUS low-risk criteria and who had a CT scan of their C-spine. Of the over 5,000 patients who had midline tenderness, only 3 had significant injuries that were missed by CT (those 3 patients had an initial exam consistent with central cord syndrome).
In 2017, the Research Consortium of New England Centers for Trauma (ReCONECT) calculated the rate of abnormal MRI after negative c-spine CT among blunt trauma patients who could not be evaluated or had persistent cervicalgia. MRI detected ligamentous injury, soft tissue swelling, vertebral disc injury, or dural hematoma in almost one-fourth of the 767 patients in this study. Only eleven (11) of them underwent cervical spine surgery, based on the MRI results. Because the clinical significance of the injuries remains unclear, the ReCONECT authors called for further consideration by trauma specialists and spine surgeons.
High-quality CT of the C-spine catches most of the injuries that would require surgical correction, and MRI is not needed in most causes to clear the c-spine even in patients that are mentally altered.
J Trauma Acute Care Surg. 2015 Feb;78:430-41. doi:10.1097/TA.0000000000000503.
J Trauma Acute Care Surg. 2016 Dec; 81: 1122–30. doi:10.1097/TA.0000000000001194
J Trauma Acute Care Surg. 2017 Feb;82:263-9. doi:10.1097/TA.0000000000001322.