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Cervical spine injury (CSI) is relatively rare, seen in only 2 to 3 percent of patients x-rayed for blunt trauma to the spine. However, because failure to diagnose acute CSI could lead to neurologic disability, doctors often order cervical spine x-rays. Since from 97 to 99 percent of these x-rays are normal, this approach is costly and subjects patients to excess radiation exposure.
Researchers involved in the National Emergency X-Radiography Utilization Study (NEXUS) prospectively studied the use of x-rays in CSI patients with blunt trauma seen at 21 emergency departments (EDs). Five NEXUS studies supported by the Agency for Healthcare Research and Quality (HS08239) and led by William R. Mower, M.D., Ph.D., of the University of California, Los Angeles School of Medicine, examined the prevalence and patterns of spinal injury among CSI patients x-rayed for blunt trauma to the spine. They also examined the usefulness of x-rays for diagnosing spinal injury in these patients. These studies are described here.
Lowery, D.W., Wald, M.M., Browne, B.J., and others. (2001, July). "Epidemiology of cervical spine injury victims." Annals of Emergency Medicine 38(1), pp. 12-16.
These researchers examined demographics and injury patterns among CSI patients undergoing ED cervical spine x-rays for blunt traumatic injury as part of the NEXUS study. Overall, CSI was
more common among the elderly, males, and patients of white or "other" ethnicity. For example,
people aged 65 or older were twice as likely to have CSI as younger people. In fact, CSI due to blunt trauma increased progressively with age. Elderly white men had the highest prevalence (5.5 percent) of any demographic group, followed by elderly white women (4.3 percent), who are prone to fractures from osteoporosis (severe loss of bone mass) that often accompanies estrogen loss during menopause.
The rate of CSI also varied by ethnicity, with the highest injury prevalence among white and Middle Eastern patients, at about 3 percent each, and lowest among blacks (1.5 percent). Also, those with "other" ethnicity (individuals who could not be classified into one of the existing categories) were nearly twice as likely to have CSI (relative risk, RR of 1.79) as other groups. Males and whites were nearly twice as likely to have CSI (RR 1.72 and 1.50, respectively). On the other hand, Hispanics were 36 percent less likely (RR 0.64) and women were 42 percent less likely (RR 0.58) to have CSI, as were blacks (RR 0.55) and those less than 18 years of age (RR 0.39).
Since CSI occurred in patients in all demographic categories, this information cannot be used to select patients with blunt trauma to the spine who should or should not undergo x-rays, conclude the researchers. Of the 34,000 patients enrolled in the NEXUS study, CSI was present in 818 (2.4 percent) of patients. Most enrolled patients were males (59 percent), as were the majority of patients with CSI (71 percent).
Goldberg, W., Mueller, C., Panacek, E., and others. (2001, July). "Distribution and patterns of blunt traumatic cervical spine injury." Annals of Emergency Medicine 38(1), pp. 17-21.
This study examined the patterns of spinal injury in the 818 patients with CSI among the 34,000 NEXUS patients x-rayed. Results showed that CSI occurred in only 2.4 percent of patients with blunt trauma who were x-rayed. The second cervical vertebra was the most common site of injury, and the sixth and seventh cervical vertebrae were involved in over one-third of all injuries. However, other spine levels were involved more often than had previously been thought.
Overall, CSI patients had a total of 1,496 distinct cervical spine injuries to 1,285 different cervical spine structures. The second cervical vertebra (C2) was involved in 24 percent of fractures, including 92 odontoid fractures. The relatively high rate of C2 injuries, particularly among the elderly, has been documented by others. Also, 39 percent of fractures occurred in the two lowest cervical vertebrae (C6 and C7). Injuries to the pedicles of the vertebral arch were relatively rare, occurring in only 6 percent of CSI patients. The vertebral body, injured in 235 patients, was the most frequent site of fracture. Nearly one-third (29 percent) of spinal injuries identified by x-ray were considered clinically insignificant.
Mower, W.R., Hoffman, J.R., Pollack, Jr., C.V., and others. (2001, July). "Use of plain radiography to screen for cervical spine injuries." Annals of Emergency Medicine 38(1), pp. 1-7.
Patients with blunt trauma to the spine usually undergo a standard three-view series of x-rays (cross-table lateral, antero-posterior, and odontoid views), as well as any other imaging tests deemed necessary by their doctors to identify CSIs. A comparison of injuries detected by screening x-rays with final injury status for each of the 818 NEXUS patients with CSIs showed that standard three-view x-rays provided reliable screening for bony CSIs among most patients with blunt spinal trauma. However, on rare occasions, these x-rays failed to detect significant unstable injuries. Furthermore, in many patients with blunt trauma, plain x-rays were not technically adequate, and additional tests such as computed tomography (CT) or magnetic resonance imaging (MRI) were needed before CSI could be excluded, thus delaying diagnosis and care, according to this study.
Plain x-rays revealed 932 injuries in 498 patients (1.46 percent of all blunt trauma patients) but missed 564 injuries in 320 patients (0.94 percent of all patients). The majority of missed injuries occurred in cases in which plain x-rays were interpreted as abnormal (but not diagnostic of injury) or inadequate. However, 23 patients had 35 injuries (including three potentially unstable injuries) that were not visualized on adequate plain film imaging. These patients represent 2.81 percent of all CSI victims.
Panacek, E.A., Mower, W.R., Holmes, J.F., and others. (2001, July). "Test performance of the individual NEXUS low-risk clinical screening criteria for cervical spine injury." Annals of Emergency Medicine 38(1), pp. 22-25.
Reducing unnecessary x-rays for patients with blunt trauma to the spine would require criteria for identifying patients at low risk for cervical spine injury. To accomplish this, NEXUS researchers identified five low-risk criteria. They concluded that cervical spine x-rays are indicated for trauma patients unless they exhibit all of the following criteria: no posterior midline cervical spine tenderness, no evidence of intoxication, normal level of alertness (for example, no disorientation or failure to remember or recall items), no focal neurologic deficit, and no painful distracting injuries (for example, long bone fracture or large burns that would impair the patient's ability to note spinal injuries).
Overall, these criteria were more than 99 percent sensitive for CSI and almost 100 percent sensitive for clinically significant CSI among NEXUS patients. All but 8 of the 818 NEXUS patients with CSI and all but 2 of the 578 patients with significant CSI were identified by using these five criteria for identifying blunt trauma patients who are at low risk for CSI. Furthermore, all of the criteria are needed if the decision instrument is to retain high sensitivity. Eliminating any single criterion would have resulted in the failure to identify some injuries.
Pollack, C.V., Hendey, G.W., Martin, D.R., and others. (2001, July). "Use of flexion-extension radiographs of the cervical spine in blunt trauma." Annals of Emergency Medicine 38(1), p. 8-11.
When standard three-view x-rays are negative for CSI in patients with blunt trauma but the doctor remains concerned about bony or ligamentous injuries, flexion-extension (F/E) x-rays of the cervical spine are often used. But F/E imaging adds little to the acute evaluation of patients with blunt trauma, according to this study. Other approaches—including MRI, CT, or delayed F/E—in the presence of specific clinical concerns would seem to provide a more reasonable approach to adjunctive imaging.
F/E views are specifically recommended most often for patients with an acceleration-deceleration mechanism and patients with pain or tenderness. These patients have the potential for a ligamentous injury that may not be apparent in a static, neutral view of the cervical spine. However, F/E views require movement of the spine, which could provoke or exacerbate neurologic injury among such patients, explain the researchers.
They reviewed the x-ray findings of NEXUS patients with CSI and tabulated how frequently F/E imaging provided diagnostically important information that was not evident on other x-rays. Of 818 patients ultimately found to have CSI, 86 (10.5 percent) underwent F/E testing. Two patients sustained stable bony injuries detected only on F/E views. Four other patients had a subluxation (partial or complete dislocation) detected only on F/E views, but all had other injuries apparent on routine cervical spine imaging.
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