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Is MRI Needed for Obtunded Trauma Patients with Normal Cervical CT Scans?
One study says yes and another, no.
Determining the best method for clearing the cervical spine (C-spine) in obtunded blunt trauma patients, particularly for cervical ligamentous injury and cord injury, is a conundrum. Failing to identify injuries can be catastrophic, and keeping patients in hard cervical collars for prolonged periods leads to decubiti and infection. Two recent studies addressed this issue.
Researchers conducted a prospective observational study of 115 obtunded blunt trauma patients who had normal 16-slice helical computed tomography (CT) scans of the neck and underwent magnetic resonance imaging (MRI) of the C-spine during a 2-year period at a single level I trauma center. Patients were defined as obtunded at the discretion of the treating physician. Patients had a mean age of 43.9, mean injury severity score (ISS) of 24.4, and mean Glasgow Coma Scale score at the time of MRI of 8.3. MRI of the C-spine identified injuries in six patients (5.2%); these included microtrabecular injury (3 patients), intraspinous ligament injury (2), cord signal abnormality (1), and cervical epidural hematoma (1). None of the injuries required intervention, and none required continued cervical collar use. The authors conclude that MRI of the C-spine might not be necessary in patients with normal CT scans. They estimate that eliminating MRI would have saved US$250,000 during the study period.
Another group of researchers conducted a retrospective study of 254 trauma patients (mean age, 42; mean ISS, 18) who underwent CT and MRI of the C-spine at a single trauma center during a 2-year period. Among 164 patients with normal CT results, MRI identified 27 cervical ligamentous or cord injuries. These injuries required surgery in 9 patients and continued use of a rigid cervical collar in 22. Among a subgroup of 46 patients deemed to be unexaminable (because of depressed mental status or significant traumatic brain injury), MRI identified cervical ligamentous injury in 4 and herniated disc in 1. The ligamentous injuries required continued use of a rigid cervical collar. The authors conclude that MRI of the C-spine is necessary in unexaminable or symptomatic patients with normal CT scans.
Comment: The debate isn’t over. The prospective study was methodologically superior to the retrospective one, but both studies, as well as others in the literature, suffer from the potential for type II error (i.e., the samples are too small to exclude the possibility of missed injury). A Nexus-like prospective multicenter analysis is needed to resolve this integral and vexing clinical concern. Until a definitive answer is available, the best approach might be to conduct MRI on obtunded patients with normal CT scans, which, at the least, will get most patients out of the collar.
— John A. Marx, MD, FAAEM, FACEP
Published in Journal Watch Emergency Medicine October 26, 2007
Citation(s):
Como JJ et al. Is magnetic resonance imaging essential in clearing the cervical spine in obtunded patients with blunt trauma? J Trauma 2007 Sep; 63:544.
- Medline abstract (Free)
Sarani B et al. Magnetic resonance imaging is a useful adjunct in the evaluation of the cervical spine of injured patients. J Trauma 2007 Sep; 63:637.
- Medline abstract (Free)