Cervical spine injury with negative computed tomography finding

The case

A 40-year-old male was brought to our hospital following a high-speed motor vehicle collision which caused him to be ejected approximately 8 m from the vehicle. The patient was found somewhat agitated with agonal respirations. Pre-hospital providers placed the patient in a rigid cervical collar on a long backboard. On arrival to our trauma admitting area, the patient was initially hypertensive with a systolic blood pressure of 170 mm Hg and a heart rate of 130 beats per minute. Neurologically, the patient was noted to be moving all extremities spontaneously but not to commands. He localized to painful stimuli, making incomprehensible sounds and opened his eyes to pain. His initial Glasgow Coma Score (GCS) was 9. Physical examination of the neck region revealed no step offs. The patient was intubated to provide a secure airway and facilitate work-up. Initial trauma radiographs demonstrated bilateral pneumothoraces and no pelvic fractures.

Q: Would plain films of the cervical spine be indicated at this time?

A: If the patient meets the National Emergency X-Radiography Utilization Study (NEXUS) criteria, then clinical examination is sufficient to clear the cervical spine (CS). When the NEXUS criteria are not met, plain films of the CS are no longer a part of routine trauma workup due to their low sensitivity. With more advanced diagnostic imaging available, plain films have become obsolete. In hospitals lacking such advances, plain films can be used for diagnosis but should not be relied upon for clearing the CS spine. In such cases, CS precautions should be followed till cleared by advanced imaging at higher centers.

Following intubation and initial radiographs, the patient was taken for a full body CT scanning. CT of the head demonstrated a left-side intraventricular hemorrhage along with a left tentorial subdural hematoma; the CS showed no acute fracture or malalignment, but there was multilevel degenerative disease (Figure 1). The chest scan again demonstrated bilateral pneumothoraces as well multiple rib fractures and areas of lung contusion – there were no other positive CT findings. Following scanning, bilateral chest tubes were placed by the trauma service and an intracranial pressure monitored placed by the neurosurgical team. Due to the patient’s neurological status and the inability to obtain a reliable clinical examination, the cervical collar remained in place. The patient was admitted to the neurotrauma intensive care unit.

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Figure 1.

Sagittal CT scan of the cervical spine taken in the immediate post-injury work-up revealing no significant injury.

On hospital day 6, the intracranial monitor was removed but the patient’s neurological examination remained poor with a persistent GCS of 6T. Due to the patient’s poor pulmonary status, an MRI of the CS was not obtained until hospital day 10, which showed a ‘near complete disruption of the ligamentum flavum at C1/C2’ (Figure 2). Neurosurgery was re-consulted and based on the MRI findings recommended to maintain the cervical collar for six weeks and clinical follow-up for re-evaluation. After a protracted hospital course, the patient was transferred to a rehabilitation center for continued care.

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Figure 2.

Sagittal cervical spine MRI taken on day 10 after injury showing the disruption of the ligamentum flavum at the C1/2 level.

Discussion

The incidence of CS injuries resulting from blunt trauma ranges from 2 to 6% ¹ and failure to identify them in a timely fashion can lead to catastrophic consequences. ² Given the criticality of the injuries, many studies have focused on accurate and timely diagnosis leading to evolving standards of care. Prior to the NEXUS study, radiographic spine imaging was extensively used to clear CS in virtually all blunt trauma patients ³ ; while detecting small number of CS injuries, it resulted in unnecessary radiation exposure in the majority of screened patients. Following NEXUS, the standard of care has shifted to clearing CS clinically without radiographic evaluation but is limited to blunt trauma patients who are awake, alert, oriented, asymptomatic and who do not have neurologic deficits, distracting injuries and do not complain of CS tenderness on palpation or pain on full range of motion.^3,4 However, the subset of patients with unreliable examination due to altered mental status and those with neurologic deficit or persistent pain cannot be cleared clinically and remain in hard cervical collar till cleared by diagnostic imaging. Since immobilization is not without side effects such as pressure ulcer formation, compromised pulmonary toilet and airway management, new interest is focused on accurately and expeditiously clearing the CS in obtunded blunt trauma patients. ⁵

Como et al. ⁵ reviewed 52 articles to construct guidelines for the Eastern Association for the Surgery of Trauma (EAST); they noted that CT has replaced plain radiography as primary screening modality for those who required imaging. Positive CT scan findings lead to specialist consultation, and further management is dictated by them. There is no universal algorithm in place to dictate the future course of an obtunded blunt trauma patient with negative CT finding. There is significant debate regarding use of MRI to diagnose ligamentous or soft tissue injuries which are not identified by the CT scan. Patel et al. ⁶ performed a systematic review of literature on the evaluation of the CS in obtunded blunt trauma patients for the EAST. They reviewed 52 scholarly articles but based on the inclusion criteria included four prospective and eight retrospective papers in the study. Due to the very low-quality evidence, they ‘conditionally’ recommended clearing the CS in obtunded patients after a negative CT scan (axial thickness ≤ 2 mm) placing emphasis on high negative predictive value (NPV) of high-quality CT in identifying unstable CS injuries (100%). ⁶ While NPV of CT for identifying stable CS injuries ranged between 50.7% and 100% (average 90.6%), the NPV for any cervical injuries ranged between 50.7% and 100% (average 88.5%). Como et al. conducted two prospective studies on the use of MRI in clearing the CS: in 115 obtunded patients with negative CT finding, six acute injuries were identified by MRI, but none of which changed the management or required long-term cervical collar. ⁷ The second study cleared 179 obtunded patients who had gross movements in all four extremities using CT scan alone and followed them up for neurologic complications which revealed no critical neurologic injuries ⁸ – hence the authors recommended CT as a safe and efficacious way to clear the CS concluded that supplemental MRI CS is not needed.

In contrast to Como et al., Menaker et al. conducted two retrospective studies comparing the use of CT and MRI to clear the CS in obtunded patients and found that MRI CS identified 8.9% ⁹ and 24.4% ¹⁰ abnormal findings in spite of negative CT reports. Based on these findings, some of these patients required operative management or remained in cervical collar for an extended time period.

There are a number of concerns and risks with the use of MRI; it is considerably more expensive than CT, and the MRI suite is often a considerable distance from the ICU which means less than optimal monitoring and staff, which can potentially place the patient at risk for an adverse event.

Summary

The algorithm to clear the CS in a blunt patient with an unreliable clinical examination remains unclear. Some advocate that CT scan alone is sufficient to rule out any clinically significant unstable injury, whereas others advocate that it is insufficient to diagnose all injuries and that MRI is still required as it alters treatment. We recommend the use of MRI–CS in blunt trauma patients with an unreliable examination even if the CS–CT demonstrates no acute injury.