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What Is the Best Way to Rule Out Spine or
Spinal Cord Injury in a Trauma Patient,
Especially When Head Injury Is Present?

Donald W. Marion

BRIEF ANSWER

Background

In 2000, the Cervical Spine Clearance ad hoc committee of the Eastern Association for the Surgery of Trauma (EAST) updated the evidence-based guidelines that it had produced in 1998.¹ The committee had identified two groups of trauma patients for whom clearing the cervical spine was difficult: individuals who were alert and awake, with normal mental status not altered by drugs or alcohol, and with no painful injuries that might distract their attention from possible cervical spine injuries; and those who had an altered mental status, most commonly due to a closed head injury. The former group was capable of describing the presence or absence of neck pain, whereas the latter group was not. The literature indicates that the ability to verify the presence or absence of neck pain in a reliable manner is very useful in identifying significant cervical spine injuries. A large amount of prospectively collected data (over 6000 trauma patients) suggests that no patient who was alert and awake at the time of evaluation and who was free of distracting pain had a clinically significant cervical spine injury in the absence of neck pain. The committee, therefore, concluded that cervical spine radiographs were not necessary for clearance of the cervical spine in these patients. However, debate persists about the most appropriate studies for clearance of the cervical spine for those patients who are unable to reliably describe the presence or absence of neck pain.

Several large studies published since 1995 support the original recommendations of the EAST guidelines regarding clearance of the cervical spine in alert, awake patients. Velmahos et al2 reported a prospective study of 549 consecutive alert, oriented, and clinically nonintoxicated blunt trauma victims with no symptoms of neck injury (class II data). In all patients, three-view plain radiographs were supplemented by axial CT through suspicious or inadequately visualized areas of the lower cervical spine. No patient was found to have a significant cervical spine injury. In a retrospective study of 267 nonintoxicated, fully oriented trauma patients, Ersoy et al³ found that no patient without neck pain or tenderness had a cervical spine injury (class III data). In a prospective study of 118 patients, Mahadevan et al⁴ documented relatively good interrater reliability (87.7%) of emergency medicine physicians for identifying altered mental status, intoxication, posterior midline tenderness, and distracting pain as clinical risk factors for cervical spine injury (class II data). Hoffman et al⁵ conducted a prospective, observational, multicenter study of 34,069 patients to determine the ability of a decision instrument employing the five criteria of no midline cervical tenderness; no focal neurologic deficit; normal alertness; no intoxication; and no painful, distracting injury to identify those blunt trauma patients who do not require cervical spine radiography. The decision instrument incorrectly identified only two patients as unlikely to have a clinically significant cervical spine injury (99.6% sensitivity, 99.9% negative predictive value); only one of these two patients underwent surgery (class I data). Despite disparities between emergency medical technicians and emergency medicine physicians in identification of those trauma patients who do not need prehospital cervical spine immobilization,⁶ there seems to be increasing support for using criteria of this type to determine which patients may be treated safely without prehospital spinal immobilization.^7,8

Clearance of the Cervical Spine in Obtunded or Comatose Patients

The recent literature provides further support for the recommendation that the upper cervical spine (C1-C2) be routinely imaged with axial CT scanning during the initial CT evaluation of the cranium (class III data).⁹ In a study of 202 patients with traumatic brain injury (TBI), Link et al¹⁰ found that 5.4% had C1 or C2 fractures that were not visualized on three-view radiographs and 4.0% had occipital condyle fractures that were not visualized by plain radiography (class II data). Blacksin and Lee¹¹ evaluated 100 consecutive trauma patients and found an 8% incidence of fractures of either the occipital condyle (3%) or C1-C2 (5%) not detected on cross-table lateral cervical spine radiographs (class II data). Further evidence also supports the conclusion that three views of the cervical spine (lateral, anteroposterior, and open-mouth odontoid) are more likely to detect cervical spine fractures than is a single lateral view (class II data).¹²

No prospective study has clearly defined the incidence of missed cervical spine injuries in obtunded patients. Although most trauma centers routinely obtain three-view cervical spine radiographs for all trauma patients admitted to the hospital, none has reported the results of follow-up imaging studies obtained at some interval after the initial three-view studies in all of these patients. As a result, the true incidence of occult instability cannot be reliably determined.

Several authors have attempted to determine the incidence of occult ligamentous instability in TBI patients with impaired consciousness. Ajani et al¹³ prospectively studied 100 trauma patients with standard three-view plain radiographs as well as a swimmer’s view if needed to visualize C7-T1 (class II data). Patients also underwent CT scanning and/or MRI for further evaluation of actual or suspected abnormalities on plain radiographs. If these studies were interpreted as normal, the patients had flexion and extension radiographs. Of the 91 patients who survived long enough for data collection, six were found to have “unstable” cervical spine injuries. In five patients, the instability was identified by the screening radiographs, but in one patient it was detected only with passive flexion/extension radiographs (although the authors also state that thin-cut CT scan of the entire cervical spine would likely have been an adequate substitute for flexion/extension radiographs in this patient, who had an abnormal neurologic examination). Sees et al14 reported a retrospective study of 20 obtunded trauma patients evaluated with flexion/extension fluoroscopy (class III data). All 20 patients had technically acceptable three-view cervical spine radiographs that were interpreted as normal prior to the flexion/extension studies. The complete cervical spine could not be visualized with flexion/extension studies in six patients. The flexion/extension studies identified subluxation at C4–5 in one of the 20 patients.

Beirne et al¹⁵ attempted to determine prospectively the incidence of cervical spine injury in 582 patients with facial fractures who presented to their trauma center over a 1-year period (class II data). Six patients were found to have cervical spine injuries, but the injuries were identifiable on three-view radiographs in only two of the six. In two patients, the injuries could be detected only with flexion/extension radiographs. Davis et al¹⁶ prospectively evaluated the utility of dynamic flexion and extension cervical spine studies performed via fluoroscopy in 301 patients with a Glasgow Coma Scale score <13 for greater than 48 hours (class II data). All patients were initially thought to have normal and adequate five-view cervical spine films, supplemented with axial CT images through any suspicious areas identified on plain films and, in the more recently enrolled patients, through the occiput-C2 region. Only two patients (0.7%) demonstrated significant instability on fluoroscopic evaluation. Another patient had a false-negative evaluation. In that case, the fluoroscopic examination visualized only C1-C6. Despite the inadequacy of the fluoroscopic study, cervical spine precautions were discontinued in that patient. She was allowed to sit up in a chair, whereupon she became quadriplegic from C6–7 and C7-T1 subluxations. Review of her initial cervical spine x-rays revealed that they had been incorrectly misinterpreted as normal even though subluxations were present at C6–7 and at C7-T1.

In three of the four studies cited above, it is possible to determine the total number of trauma patients who had flexion/extension radiographs.^13,14,16 Meta-analysis of these three studies reveals an incidence of 5/412 (1.2%) of occult cervical spine injury not identified with three-view radiographs plus CT supplementation. It is important to note that spinal cord injury was not caused by passive flexion/extension in any of these patients.

A practical difficulty that is commonly encountered during attempted fluoroscopic flexion and extension cervical spine studies in the supine position is inability to visualize the lower cervical spine. Bolinger et al¹⁷ described their attempts to perform fluoroscopic flexion/extension cervical spine studies in a series of 56 consecutive, comatose, pharmacologically paralyzed head-injured patients (class II data). They were able to visualize the entire cervical spine in only two of these 56 patients. In such cases in which the lower cervical spine cannot be visualized by bedside fluoroscopy, the best alternative may be MRI. Unfortunately, although MRI is very sensitive for detecting soft tissue injuries, particularly within the first 48 hours of injury (class II and class III data),^18–21 there exists no good evidence to show that minor injuries detected with MRI represent true instability. In fact, it has been stated that MRI may overestimate true instability in as many as 25 to 40% of patients (class III data).²²