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Authors: S.V. Mahadevan, MD, FACEP, Assistant Professor of Surgery/Emergency Medicine, Stanford University School of Medicine;
Associate Chief, Division of Emergency Medicine, and Medical Director, Stanford University Emergency Department, Stanford, CA; and Misty Navarro, MD, Senior Emergency Medicine Resident, Stanford-Kaiser Emergency Medicine Residency, Stanford, CA.
Reviewer: Andrew D. Perron, MD, FACEP, FACSM, Residency Program Director, Maine Medical Center, Portland, ME.
Dealing with potential cervical spine injuries (CSIs) is a frequent occurrence for any physician who manages trauma patients. The importance of the routine practice of clearing the cervical spine should not be underestimated. Missed spine fractures may have devastating consequences for both the patient and the physician. Although evaluating a patient with a potential CSI is common, many controversies exist regarding immobilization, imaging selection, and management strategies. Since, fortunately, CSIs are relatively uncommon, large, controlled series with definitive answers do not yet exist. The author has created an outstanding, two-part article that presents the evidence currently available for evaluation and clearance of the cervical spine in adult trauma patients. The first part of this series reviews cervical spine immobilization, patient selection for imaging and clinical decision rules for cervical spine radiography. This two-part article is critical for any physician who manages patients with potential cervical spine trauma.—The Editor
The evaluation of the cervical spine for potential injury is viewed widely as one of the most challenging aspects of trauma care. Though neck pain and tenderness are common findings in trauma patients presenting to the emergency department (ED), CSI is found in only 0.9-6% of all blunt trauma patients.1-5 The emergency physician’s goal is to identify patients with injuries that could result in permanent dysfunction or catastrophic disability. The implications of a missed injury are profound and could have life-altering consequences for the both the patient and physician. Lifetime medical care costs exceed $1 million per injury victim, while the annual nationwide care costs for these patients exceed $2 billion.6 In one series, missed spinal fractures were responsible for 3% of malpractice claims, and ensuing spinal cord injuries accounted for more than 9% of total dollars paid in claims.7
Therefore, it is not surprising that this area has been the subject of extensive research and controversy in an attempt to define the most accurate and cost-effective approach to clearing the cervical spine. This two-part review article will describe the evaluation of traumatic CSIs, including when to suspect CSIs, how to protect the cervical spine from further injury, the practice of clinical cervical spine clearance, radiographic clearance of the cervical spine, the diagnosis of isolated ligamentous injury, and the syndrome of spinal cord injury without radiographic abnormality (SCIWORA). This review will focus primarily on patients 14 years and older as anatomic and biomechanical features of the pediatric cervical spine differ significantly from those of the adult. For further information regarding pediatric cervical spine injuries please refer to the July 2003 edition of Trauma Reports, "Pediatric Cervical Spine Injuries: Avoiding Potential Disaster."
Suspicion of Cervical Spine Injuries
More than 1 million blunt trauma patients with potential CSIs are evaluated in U.S. EDs each year; approximately 30,000 of these patients have cervical spine fractures or dislocations, and 10,000 of these patients suffer spinal cord injury.3,8,9 Fractures of the cervical spine are not always readily apparent. CSIs are the most commonly missed severe injury with serious implications for the patient and physician.10 Failure to identify the neurologically intact patient with an unstable fracture or ligamentous injury may lead to the development or progression of severe neurologic compromise. Patients with a delayed or missed initial diagnosis of CSI have been found to have an associated 7.5-fold increase in the incidence of secondary neurologic injury as compared with patients in whom the diagnosis is made initially.9 One group of authors emphatically states, "A single missed unstable CSI is an unacceptable disaster."11 Considering the large number of trauma patients evaluated each year and the potential consequences of a missed CSI, the question arises: In whom should we suspect CSI? While it is true that all blunt trauma victims are potentially at risk, certain historical and clinical features may raise the clinician’s level of suspicion.
On a global level, traffic accidents involving motor vehicles, bicycles, or pedestrians account for the majority of CSIs and almost 50% of all spinal cord injuries.12 Falls, sporting and recreational accidents, work related injuries, and violence are responsible for the remainder of adult spinal cord injuries.12 Falls account for the most frequent cause of cervical spine injuries in adults older than 65 years.13-15 Some authors have attempted to identify patients with characteristics placing them at increased risk for CSI. (See Table 1.)
Table 1. High-risk Criteria for CSI
Generally accepted, high-risk mechanisms of injury include high-velocity blunt trauma (e.g., motor vehicle accidents at speeds more than 35 mph), motor vehicle accidents with a death at the scene, a drowning or diving accident, and falls from higher than 10 feet.16-19 While the mechanism of injury alone has not been shown to be a predictor of clinically significant CSI, providers should maintain a high index of suspicion when evaluating patients from such accidents.17,20 Concomitant use of alcohol or other intoxicants in these settings also should raise the possibility of injury, as their use is associated with increased risk-taking behavior and may produce an unreliable clinical examination. High-risk physical exam findings include evidence of direct cervical injury, the presence of pelvic or extremity fractures, altered mental status, significant head or facial injury, evidence of a thoracic or lumbar fracture, and paresthesias or burning in the extremities.16-19
Patients with a history of a prior cervical spine disease or surgery, or disease states characterized by a rigid spine (e.g., ankylosing spondylitis, diffuse idiopathic hyperostosis) are also at increased risk of CSI. In this subset of patients, less force generally is required to produce an injury; therefore, what might be considered relatively minor trauma actually may result in a significant CSI.21 These patients generally suffer from chronic pain; therefore, differentiating an acute vertebral injury from a chronic process may be more difficult.
Patients older than 65 years have an increased relative risk (RR 2.09; 95% CI 1.77-2.59) of CSI.22 The prevalence of cervical spine fractures among elderly patients is greater than all other age groups.23 This fact has been attributed to the tendency of elderly patients to fall, their increased risk for motor vehicle accidents, and the significant incidence of senile osteopenia.13,14 Unlike young adults, elderly patients are more likely to sustain injuries from low-energy mechanisms. In one study, falls from standing or seated heights—a mechanism unlikely to produce injury in young adults—accounted for 30% of CSIs in those 65 years or older and 40% of injuries in patients older than 75 years.13
Protecting the Cervical Spine
During the initial evaluation of any trauma patient, assume that the cervical spine may be injured. An important consideration in such patients is the prevention of pathological motion of injured cervical vertebrae, which may create or exacerbate a spinal cord injury. (See Figures 1A and 1B.) It is estimated that 3-25% of spinal cord injuries occur after the initial traumatic insult, either during transport or early in the course of management.24 Rogers et al found that 10% of spinal cord injuries occurred or were exacerbated following the initiation of medical care.25 The mishandling of such patients has been associated with poor clinical outcomes.24
As the unstable cervical spine is prone to additional injury from manipulation, complete spinal immobilization has been utilized to limit motion until a spinal injury has been excluded. Proper and secure spinal immobilization is accomplished with a long backboard, a rigid cervical collar, lateral support devices (e.g., tape blocks or towel rolls), and tape or straps to secure the patient to the backboard.26 Padding may improve positioning and comfort.
Early management of the patient with a potential CSI begins with proper immobilization at the scene of an injury. Emergency medical service personnel are trained to immobilize any trauma victim with potential for CSI—symptomatic or not. As a result, cervical spine immobilization is one of the most frequently preformed prehospital procedures.26 An estimated 5 million patients are immobilized at a cost of $75 million a year in the United States.27 This conservative practice arose from reports citing lack of immobilization as the cause of neurological deterioration among acutely injured trauma patients transported to medical facilities for definitive care. In a retrospective case series report, 26% of the 123 trauma patients reviewed suffered major neurologic deterioration prior to admission to the hospital as a result of patient mishandling. The report cited failure to immobilize the patients as the primary cause.28 Though immobilization makes sense and provides theoretical protection, no case control studies or randomized trials have addressed the effect of spinal immobilization on clinical outcomes after CSI.24
Furthermore, spinal immobilization carries inherent risks and has a modest morbidity. Complaints of occiput and back pain are common following immobilization, and immobilization also may result in unnecessary radiographic evaluation.29 Immobilization increases the risk for aspiration, impairs normal respiratory function, and places patients at risk for pressure sores.30,31 Patients at greatest risk for pressure sores are those who remain on the spine board for more than two hours without being turned.32 The application of rigid cervical collars is associated with elevation of intracranial pressure (ICP) and potentially could exacerbate a concomitant head injury.33 In certain cases, the application of the hard collar itself actually may do more harm than good. Papadopoulos et al describe a case of an 82-year-old male with ankylosing spondylitis and a fixed flexion deformity of the cervical spine who walked into an ED complaining of neck pain after a fall. After plain films revealed a fracture at C6, the patient was placed in a rigid cervical collar (See Figure 2A.), subsequently leading to an iatrogenic spinal cord injury and death.34 Rather than forcing a patient with fixed flexion deformity into a neutral position, it may be better to simply immobilize the patient in flexion to prevent further injury. (See Figure 2B.)
Figure 2. Immobilization of Patient
with Fixed Flexion Deformity
While evaluating a patient with a potential CSI, it is important to maintain cervical spine precautions until an injury has been excluded. Techniques for moving patients with spine fractures are designed to protect and preserve neurologic function. The logroll maneuver commonly is employed to remove a patient from the backboard or examine the thoracic and lumbar spine. In this technique, one person stabilizes the head and neck while assistants turn the body, turning the patient as one unit. (See Figure 3.) The logroll maneuver should be performed with care as it presents an opportunity for movement of the spine at an unstable segment.35 Alternatives to the logroll maneuver include the HAINES method (High Arm IN Endangered Spine) and the multihand/fireman lift.
If the patient requires emergent airway management, precious time should not be wasted obtaining a single lateral radiograph of the cervical spine to exclude a CSI. This approach delays definitive airway management and provides a false sense of security; a single view is inadequate to exclude a CSI. Numerous studies have shown that the proper, safe, and effective approach to managing these patients is rapid sequence intubation with in-line immobilization.36-40 This approach does not significantly increase the risk of neurologic injury in unstable cervical spine fractures. Paralyzing the patient reduces the risk of patient movement during intubation while immobilization of the head and neck in the neutral position throughout the procedure prevents hyperextension of the neck by the laryngoscopist. (See Figures 4A and 4B.)
Clinical Decision Rules for Cervical Spine Radiography
In addition to maintaining a high level of suspicion of possible CSI, trauma care providers should have an organized, thoughtful approach to the evaluation of these patients. The high-risk nature of these injuries raises the question: Do all blunt trauma victims need routine cervical spine imaging?
During the 1970s and 1980s, several papers cautioned physicians about the occurrence of occult or painless CSIs in blunt trauma victims.41-46 Researchers in one study went as far as to recommend that all blunt trauma patients should have a lateral radiograph to exclude CSI, a recommendation that persists in Advanced Trauma Life Support training to date.47 However, careful review of the literature finds these occult or painless injuries were not truly asymptomatic;48 that in each of these cases, either the patient was evaluated inadequately or had a clinical finding that increased the risk for a CSI.
Fear of missing an occult CSI in the multi-system trauma patient has prompted many physicians to order cervical spine radiography on virtually all blunt trauma patients, regardless of their clinical presentations. The result is that many cervical spine x-rays are ordered to detect a few injuries; 98% of these radiographic studies are normal or negative.49 Each year in the United States, an estimated 800,000 cervical spine radiographs are ordered by 25,000 emergency physicians at a cost of $180 million per year.49 It is predicted that the radiation from these studies will lead to 3,760 thyroid cancers.2
Imaging all blunt trauma victims also leads to prolonged ED work-ups, lengthy immobilization, and may delay other therapeutic interventions and the care of other ED patients. To conserve resources, prevent morbidity, and act in a cost- and time efficient manner, a risk stratification approach is necessary to determine which patients require imaging.
During the late 1980s and early 1990s results from several small studies suggested that patients with certain low-risk clinical criteria have a low probability of CSI.17,20,50-59 The largest of these studies had a sensitivity of 100% for excluding injury, but did not include enough patients (n=974) or cervical spine fractures (n=27) to justify widespread use.49
National Emergency X-Radiography Utilization Study (NEXUS). Results from the NEXUS trial presented clinicians with strong evidence to support the selective exclusion of cervical spine imaging in low-risk, blunt trauma patients. NEXUS consisted of a large, federally supported, multi-center, observational study designed to validate a clinical decision rule comprising five clinical criteria, commonly known as the NEXUS low-risk criteria.
The five clinical criteria (See Table 2.) include: 1) tenderness at the posterior midline of the cervical spine; 2) focal neurologic deficit; 3) abnormal level of alertness; 4) any evidence of intoxication; and 5) clinically apparent painful injury that might distract the patient from the pain of a CSI. The presence of any one criterion mandates the need for cervical spine radiography. The absence of all five clinical criteria strongly suggests that a patient has a low probability of CSI and, therefore, does not require cervical spine radiographs.
Table 2. NEXUS Criteria
This NEXUS trial enrolled 34,069 patients at 21 different EDs across the United States—more than 20 times as many patients with CSI than any previous study. Of the 818 patients in this study with CSIs, all but eight injuries were identified by the presence of one of the five aforementioned criteria. Of the eight missed injuries, only two were considered clinically significant and only one required surgery. The patient requiring surgery was a 57-year-old male who was a belted driver involved in a head-on collision. He briefly lost consciousness; had scapular and clavicular tenderness and right arm paresthesias; and was diagnosed with a clavicle fracture and a C6 lamina fracture. In retrospect, this patient actually may represent a misapplication—rather than a failure—of the clinical decision rule as the patient had a loss of consciousness, a clavicle fracture, and paresthesias.60
Overall, the five clinical criteria had a sensitivity of 99.0% and a negative predictive value of 99.8%. Using this clinical decision rule, the authors found that cervical spine x-rays could have been avoided in 4,309 patients (12.6%)—translating into a substantial reduction (approximately 100,000) in the number of cervical spine radiographs ordered in the United States each year, a cost savings of approximately $100 million annually and 474 fewer predicted thyroid cancers. The NEXUS trial’s findings subsequently were validated in both the pediatric and geriatric populations.61,62
Though the five clinical criteria were not defined explicitly, the individual criteria and decision rule as a whole showed good to excellent interobserver reliability.63 A distracting painful injury (DPI) was not defined explicitly, but described as any painful injury that potentially could distract the patient’s attention from a CSI. (See Table 3.) On data analysis of a subset of patients’ from the NEXUS database, researchers found that fractures (58%) and soft-tissue injuries (16%) accounted for the majority of DPIs.64
Table 3. Distracting Painful Injuries
Canadian C-spine Rule (CCR). In hopes of narrowing the scope of patients requiring imaging, the Canadian C-spine group conducted a large, prospective, cohort study to generate data for a new decision rule. The group’s paper contended that although the NEXUS criteria were highly sensitive (99.6%), the rule’s reduced specificity (12.9%) could lead to patients being imaged unnecessarily.65
Results from the CCR derivation study generated a decision rule comprising three sequential questions to determine if imaging is necessary.65 (See Figure 5.) The first question screens the patient for any high-risk factors that mandate radiography. These high-risk factors include age older than 65 years, a dangerous mechanism, and paresthesias in the extremities. The authors clarify what constitutes a dangerous mechanism to include such events as a fall from higher than 3 feet, axial load to the head, a high-speed motor vehicle collision (MVC), a bicycle collision, and a motorized recreational vehicle accident. If a high-risk factor is deemed present, the patient should undergo an imaging study; if not, one proceeds to the next question.
The second question seeks to determine if there is a single, low-risk criterion that might allow for safe assessment of range of motion. The low-risk criteria are defined as a simple, rear-end MVC, patient in a sitting position in the ED, patient ambulatory at any time, delayed onset of neck pain, or absence of midline cervical spine tenderness.
If any one of these low-risk factors is present and all high-risk factors are absent, the third question is asked: Can the patient actively rotate the neck 45° both to the left and right? If the patient is able to complete this task, the CCR states cervical spine imaging is not required.
This derivation study consisted of 8,924 patients with 151 clinically important fractures. The authors determined that the CCR had a sensitivity of 100%, identifying all 151 clinically important fractures, and had a specificity of 42%. They estimated that use of the CCR would result in a 15.5% reduction in cervical spine radiography, compared with a 12.6% reduction using the NEXUS clinical decision rule.
However, the CCR has explicit exclusion criteria and cannot be used with any of the following patient populations: 1) age younger than 16 years; 2) abnormal Glasgow Coma Scale score; 3) abnormal vital signs; 4) injury older than 48 hours; 5) penetrating trauma; 6) paralysis; 7) history of vertebral disease; 8) patient seen previously for the same injury; or 9) pregnancy.
NEXUS VS CCR. The CCR validation study consisted of 8,283 patients with 169 clinically important injuries and dealt with the confirmed results of the derivation study. The authors found the Canadian C-spine Rule had a sensitivity of 99.4% and a specificity of 45.1%. One of the 169 clinically important injuries was missed using the CCR.66 However, in 845 cases —almost 10% of the study’s patients—the study physicians were uncomfortable testing the patient’s range of motion for unclear reasons. The inclusion of these patients could have affected the CCR’s sensitivity or specificity adversely. Additionally, using the CCR, the study physicians misinterpreted the need for radiography in 5.2% of cases.
In addition to validating their rule, the CCR authors decided to retest the NEXUS low-risk criteria against their derivation and validation study populations.66,67 They found NEXUS low-risk criteria had only a 90.7-92.7% sensitivity, and that use of the NEXUS rule would have missed 7-10% of patients with clinically important cervical spine injuries. These findings were in stark contrast to the NEXUS validation study, which found the rule to be 99.6% sensitive and was inconsistent with the large body of literature collected prior to the NEXUS trial.68 Considering there are approximately 11,000 CSIs in the United States each year and based upon CCR studies’ findings, the NEXUS decision rule could miss as many as 1,000 injuries each year. Yet, since the publication of the NEXUS validation study, there have been no case reports of injuries missed by the NEXUS criteria.
What could account for such a discrepancy? A number of methodological issues make interpretation of the NEXUS rule using CCR data suspect. The study physicians’ failure to detect certain physical findings and the use of surrogate criteria introduces the potential for misclassification errors. For example, a fractured mandible and distal radius fracture were not classified as distracting injuries, and patients with extremity paresthesias were documented as not having a focal neurologic deficit. Such misclassification errors could result in inappropriate use of any clinical decision rule and serious medical errors.
Rather than being forced to choose one rule or the other, the astute clinician should be familiar with both, and employ them based upon the clinical scenario. In some instances, the combination of the rules may improve the positive predictive value while maintaining a high sensitivity.68 As Mower and Hoffman positively note, "the development and validation of the NEXUS criteria and Canadian C-spine rule represent an embarrassment of riches for emergency physicians, who will have the luxury of choosing to use either or both of these instruments, depending on their clinical setting, ease and applicability, and individual practice styles."68
The first part of this two-part series has focused on the identification of patients at risk for CSI, immobilization, and controversies regarding the indications for radiographs. Early identification of patients who are high-risk for CSI, either based on the mechanism of injury, age, previous cervical spine disease process, or use of mind-altering substances will facilitate an early diagnosis and protection of the spine. Complete immobilization of the cervical spine will prevent additional injury to an unstable cervical spine and minimize further neurologic deterioration. In addition, physician awareness of the currently available clinical decision rules for cervical spine radiography may assist in a timely diagnosis for injuries and eliminate unnecessary radiographs in the appropriate patient categories. Part two of this series will include a discussion of imaging modalities for cervical spine trauma including plain radiographs, flexion/extension films, CT, and MRI. A thorough discussion on ligamentous CSIs will be presented as well as a discussion of SCIWORA.
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