ED use of flexion-extension cervical spine radiography in the evaluation of blunt trauma

ED Use of Flexion-Extension Cervical Spine Radiography in the Evaluation of Blunt Trauma WILLIAM J. BRADY, MD,* JOHN MOGHTADER, MD,* DANIEL CUTCHER, CHARLIE EXLINE, RN,I" JEFFREY YOUNG, MD::I: Dynamic cervical spine radiography (CSR) is used to detect ligamentous instability. We investigated the ED use of dynamic CSR through a retrospective descriptive review using a convenience sample study design at a university emergency department. Adult blunt trauma patients with static (lateral, AP, odOntoid) and dynamic (flex, extend) CSR participated. 451 patients (52% male with mean age of 33.6 years) met entry criteria. Injury mechanisms were 74% MVA, 12% fall, 8% direct trauma, and 6% other. Indications for dynamic CSR were 100% traumatic mechanism, 86% neck pain, 70% midline neck tenderness, and 18% abnormal static CSR. Static CSR were normal in 372, 5 of which had abnormal dynamic CSR (5 cervical contour line disruption [CCLD], 2 posterior element abnormality [PEA]); of these 5 patients, none required invasive stabilization. Static CSR were abnormal in 79:patients (38 CCLD, 30 lordotic curve reversal, 17 PEA, 4 soft tissue swelling) of which 16 had abnormal dynamic CSR (9 increased CCLD, 4 PEA, and 4 fracture); of these 16 patients, 4 required invasive stabilization. Final diagnoses were 428 cervical soft tissue injury, 11 subluxation, 8 fracture, 2 fracturesubluxation, and 2 spinal cord injury without radiographic abnormality. Spine consultation was made in 12%. Stabilization therapy was required: 21 soft collar, 4 surgical, 3 halo-device, and 5 other. No complications of dynamic CSR were noted. The blunt trauma patient with neck complaints and an abnormal static CSR was more likely to have an abnormal dynamic CSR demonstrating a cervical injury requiring stabilization compared to patients with normal static CSR. (Am J Emerg Med 1999;17:504-508. Copyright © 1999 by W.B. Saunders Company)

injury, Traditional cervical spine radiography--ie, the threeview trauma series---detects the cervical spine fracture with reasonable accuracy; such detection of ligamentous injury, however, is less impressive. Much of the recent literature has focused on correct patient selection as well as the optimal radiographic approach. 1-6 Unfortunately, little emphasis has been placed on the issue Of flexion-extension cervical spine radiography. 7,8 Flexion-extension (FE) cervical spine films are termed dynamic in that the technique places mechanical stress on the cervical spine via movement. With significant ligamentous injury, movement of one vertebral body relative to adjacent vertebral structures is encountered. The standard 3-view trauma series demonstrates fracture reliably yet is quite poor in its detection of ligamentous injury. The use of FE views has been theorized to improve the clinician's ability to detect such injury, v,8 Unfortunately, despite widespread use 9 of the technique by emergency physicians and other clinicians evaluating the blunt trauma patient, little scientific information is found in the literature supporting their correct use. We undertook the following retrospective study of FE cervical spine radiography in the blunt trauma patient to determine the utility of such views.

Accurate, rapid detection of cervical spine injury is mandatory in the initial evaluation and management of the blunt trauma patient. Patients with neck pain presenting to the emergency department (ED) after a blunt traumatic incident may have a clinically insignificant soft tissue disorder (ie, muscular spasm), bony fracture, or ligamentous

METHODS

From the *Department of Emergency Medicine, University of Virginia School of Medicine, the 1"Department of Emergency Medicine, University of Virginia Health Sciences Center, and the :l:Department of Surgery, University of Virginia School of Medicine, Charlottesville, VA. Manuscript received March 27, 1998, returned May 12, 1998; revision received June 12, 1998, accepted July 9, 1998. Presented in part at the Society for Academic Emergency Medicine, New England Regional Meeting, Providence, RI, April 1997, the American College of Emergency Physicians Scientific Assembly and Research Forum, San Francisco, CA, October 1997, and Trauma Tactics, Orlando, FL, April 1998. Address reprint requests to Dr Brady, Department of Emergency Medicine, Box 523-21, University of Virginia Health Sciences Center, Charlottesville, VA 22908. Key Words: Cervical spine injury, subluxation, ligament, cervical spine radiography, trauma, blunt trauma. Copyright © 1999 by W.B. Saunders Company 0735-6757/99/1706-0002510.00/0 504

A retrospective descriptive study was performed over a 2-year period from July 1, 1992, to June 30, 1994 in the ED of an academic medical center with an approximate annual volume of 60,000 patient-visits. The patient population represented a convenience sample of blunt trauma patients who underwent cervical spine radiography (CSR) as defined below; entry criteria included the adult blunt trauma patient aged greater than 18 years who underwent CSR, including both static (lateral, anteroposterior, and odontoid) and dynamic views (lateral flexion and extension). The radiographic studies were obtained at the discretion of the treating and attending physicians. The study was reviewed and approved by the Human Investigation Committee of the study institution or a retrospective investigation. Information obtained from the emergency department, hospital, and radiology records included patient age and gender; type of traumatic mechanism (motor vehicle accident, fall from a height, or direct head-neck trauma); transport method to ED (ground ambulance, air ambulance, or private automobile); presence of cervical immobilization in prehospital setting; time to onset of pain after injury and time to ED evaluation after injury; indications for dynamic cervical spine radiography (neck pain, tenderness, or abnormal static cervical spine radiography); attending radiologists' interpretation of cervical spine radiographs (static and dynamic); ultimate hospital diagnoses related to cervical spine; complications

BRADY ET AL • FLEXION/EXTENSION CERVICAL SPINE RADIOGRAPHY

of dynamic cervical spine radiography; and neurosurgical consultation performed in the ED for cervical injury; and neurosurgical therapy. No determinations of outcome beyond the ED (in discharged patients) and/or hospital admission were made in this convenience sample. Dynamic CSR at the study institution was performed by radiology technologists in the following fashion. The patient actively first flexes and then extends the neck to the point at which pain is encountered; radiographs are obtained at the 2 points of maximal movement and then compared to the static lateral view. Abnormalities of the cervical spine noted on the static 3-view series included disruption of the lines of cervical contour (anterior and posterior vertebral lines, spinolaminar line, and spinous process line), soft tissue swelling (greater than 7 rnm adjacent to vertebral body C-2 and greater than 22 mm at C-7), and reversal of the lordotic curve. Disruption of the lines of cervical contour included any degree of subluxation greater than 3 ram. Obvious pathological subluxation was considered a diagnostic finding and did not undergo dynamic cervical radiography in the El). The criteria for abnormality included: (1) movement of the anterior and/or posterior vertebral lines of one vertebral body by greater than 3 mm relative to the adjacent vertebral boy; (2) divergence of spinous processes; and (3) widening of the atlanto-dental interval by more than 3 ram. Adequacy of dynamic CSR was not made unless remarked upon by the attending radiologist.

RESULTS There were 467 patients who met entry criteria; 16 (3.5%) patients were excluded from the study due to incomplete medical records. There were 451 patients used for data analysis. The mean age was 33.6 years (range 18-82 years of age), with 52% male patients. The traumatic mechanism responsible for the neck injury was motor vehicle accident in 334 (74%) patients, falls from a height in 54 (12%), direct trauma to head-neck region in 36 (8%), and other in 27 (6%). See Table 1 for additional demographic information. The abnormalities noted on static CSR are listed in Table 2. Abnormalities noted on dynamic CSR are listed in Table 3. Of note, 372 patients (82.5%) had a normal static CSR series with only 5 (1.3%) of these patients with abnormal dynamic CSR. Seventy-nine patients (17.5%) had abnormal static CSR with 16 patients (20.3%) of this group revealing abnormality on dynamic views (P < 0.001 for normal static v abnormal static CSR as a predictor of abnormal dynamic CSR). Figure 1 depicts the results of both static and dynamic CSR in the study group. No complications were observed resulting from dynamic CSR performance; no deaths were reported in the patient group. Ultimate diagnoses related to the cervical spine are TABLE1. Patient Information Variable

Result

Total number of patients Age (mean, in years) Number of male patients (%) Transport method to ED (%) Ground ambulance Air ambulance Other Spine immobilized prehospital (%) Time intervals (mean, in hours) injury to neck pain onset Injury to ED evaluation

451 33.6 235 (52) 419 (93) 4 (1) 28 (6) 418 (99) 0.23 3.1

505

TABLE2. Abnormality on Static CSR Radiographic Abnormality

Number (%)

Disruption of lines of cervical contour Reversal lordotic curvature Posterior element abnormality Prevertebral soft tissue swelling

38 (8.4) 30 (6.7) 17 (3.8) 4 (1.0)

depicted in Table 4. Neurosurgery was consulted in 54 cases (12%); invasive neurosurgical therapy was deemed necessary in 7 patients (1.6%). Extended use of soft cervical support was recommended in 26 (5.8%) patients with repeated neurosurgical outpatient evaluation.

DISCUSSION Whiplash is an injury caused by hyperextension and subsequent hyperflexion of the cervical spine associated with sudden acceleration and deceleration of the body in relation to the head. The use of FE radiography in this type of mechanism to diagnose occult fractures or subluxation has been used for more than 30 years. 1° Their use, however, in the acute setting at the time of initial evaluation was not formally advocated until 1960.11 In 1980, Wales et al presented an algorithm that subsequently remains as the standard of care in the evaluation of the trauma patient in whom cervical spine injury is suspected. 7 According to the algorithm, flexion-extension views were advocated in the patient with severe or persistent neck pain; further, patients with a suspicious or equivocal 3-view (trauma series) in whom anteroposterior and lateral thin section tomography was negative for fracture were also candidates for FE views. Whereas emergency physicians evaluating acute neck injury not uncommonly obtain FE views in lieu of or before conventional or computed tomography, the basic algorithm is generally accepted to this day despite lack of clinical, prospective studies to support their use. Evidence prior to 1980 for the incorporation of FE studies into this algorithm came from various case reports and series describing patients in whom 3-view cervical spine radiography did not initially show injuries and in whom FE films TABLE3. Abnormality on Dynamic CSR Number (%) With Normal Static CSR Radiographic Abnormality (n = 372)

With Abnormal Static CSR (n = 79)

P Value

Disruption of lines of cervical contour Posterior element abnormality Fracture

5 (1.3)*

9 (11.4)t

<0.001

2 (0.5)* 0

4 (5.t)t 4 (5.1)t

<0.001 <0.001

Total abnormalities

7

17

<0.001

NOTE: *A total of 5 patients demonstrated 7 abnormal findings on the dynamic radiographic views. Two patients had both disruption of contour lines and posterior element abnormalities simultaneously. tA total of 16 patients demonstrated 17 abnormal findings on the dynamic radiographic views. One patient had both disruption of contour lines and posterior element abnormality simultaneously.

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451 patients with 3-view C-spine series

372 n

367 normal

~

5 abnormal

abnormal

Z

63 normal 16 abnormal

FIGURE. Flow chart of patients undergoing dynamic CSR. NOTE:F/E views, flexion/extension CSR obtained. identified patterns consistent with a strain etiology.1>15 A 1991 study retrospectively evaluated the utility of FE views in the ED traumatic neck pain patient and concluded that dynamic views increased the sensitivity of the ED evaluation of the traumatic neck pain patient, although minimally so, and did not reach a statistically significant level. They also felt that further studies were required to further define the issue. 8 Subsequently, solid evidence supporting either the use or lack of use of FE films has not been published. Emergency physicians continue to use FE views in a not-insignificant minority of blunt trauma neck pain patients without a solid scientific basis. 9 The current recommendations for performing a FE study include patients who are alert and cooperative; these patients should lack significant, distracting, painful injury as well as neurological complaint or finding. Obvious fracture or dislocation on the 3-view CSR series also contraindicates their use in that the initial diagnosis of cervical injury has already been made. Table 5 reviews the various reported indications and contraindications for dynamic CSR according to various emergency medicine, radiology, orthopedic surgery, and neurosurgery sources. 7,8,16-2°Interestingly, these recommendations are not attributed to primary references other than medical opinion or theoretical/anecdotal evidence. The American College of Radiology (ACR), in its publication entitled Appropriateness Criteria for Imaging and Treatment Decisions, 16 uses somewhat board terminology, suggesting that dynamic CSR should be used in clinical situations involving suspected ligamentous injury with both normal neurological assessments and normal static CSR. Rosen's Emergency Medicine: Concepts and Clinical Practice 17 adds the presence of a normal mental status with severe neck pain or tenderness; in direct contrast to the ACR policy statement, 16 minimal abnormality on static CSR is TABLE4. Ultimate Diagnoses Related to the Cervical Spine Cervical Spine Injury

Number (%)

Soft tissue injury Fracture Subluxation Fracture/subluxation SCIWORA*

428 (94.9) 8 (1.8) 11 (2.4) 2 (0.4) 2 (0.4)

*Spinal cord injury without radiographic abnormality.

considered an indication in this emergency medicine publication. Mechanistic indications are suggested by Harris and Harris' Radiology of Emergency Medicine.18 The orthopedic and neurosurgical texts use only broad statements such as the suggestion of spinal instability as indication for dynamic CSR. x9,2° The findings of our study appear to support the indication recommendations in Emergency Medicine: Concepts and Clinical Practice, at least in the patient group who had their therapy altered by the results of the dynamic CSR. 17 In a survey of practicing emergency physicians regarding the use of FE CSR, 21 the following indications were reported at the following rates: (1) minimal disruption of cervical contour lines 68%, (2) posterior element interval widening 53%, (3) cervical tenderness 49%, (4) cervical pain 45%, (5) radiographic prevertebral cervical soft tissue swelling 38%, and (6) injury mechanism 34%. In this same survey, reported contraindications to FE CSR were: (1) altered mentation 91%, (2) focal neurological issue (complaint or examination finding) 88%, (3) painful distracting injury 71%, (4) nonEnglish speaker 50%, and (5) young patient age (defined at < 7 years) 29%. 21 In this study, 21 with normal FE CSR results, 27% of practicing emergency physicians would use additional imagining studies: computed tomography (CT) 56%, plain-film oblique views 19%, and magnetic resonance imaging (MRI) 7%. When the emergency physician requests consultation in the blunt trauma patient with concern for cervical injury, the consultant recommends FE CSR in 71% involving the radiologist and 41% involving the spine surgeon. 21 The test is performed by having the patient actively flex and extend the neck only to the point of pain; the movement should not be encouraged beyond that which is painful. The test should be performed under direct medical supervision although many centers do not require such; our institution does not require a physician's presence for the performance of the FE views which in 451 uses did not cause problem. Interestingly, several of the sources listed in Table 5 suggest that a physician--at times, a spine surgeon--should be present to perform the study. In the survey study of FE CSR use, 52% of practicing emergency physicians do not accompany the patient to Radiology nor supervise the performance of the study.21 Further, they also recommend that direct fluoroscopic visualization is required in all applications of the dynamic CSR technique. 7,19,2°The criteria for abnormality include obvious subluxation greater than 2 mm as well as an accentuation of existing subluxation on the static lateral view. Further instability definitions are controversial, but a summary of suggested signs is available. 7 The issue of muscle spasm has long been known to be a potential confounder in the interpretation of FE films in the acute setting; this is particularly true for the emergency physician. It has been noted that whereas the presence of paraspinal spasm on physical exam may imply an unstable cervical injury, it may also limit the amount of flexion and extension possible. Such patients may demonstrate a falsely negative radiographic examination. 15 The advent of MRI has further elucidated the potential confounding issue of muscle spasm in the acute evaluation of the injured cervical spine. One such study suggests additional followup several days after

BRADY ET AL • FLEXION/EXTENSION CERVICAL SPINE RADIOGRAPHY

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TABLE5. Suggested Indications and Contraindications for Dynamic CSR According to Various Sources Suggested Indications

Reference Emergency Medicine: Concepts & Clinical Practice ~7 The Radiology of Emergency Medicine~8 Neurosurgery19 Operative Orthopaedics2° American College of Radiology~6 Brady et a121 Wales et al7 Lewis et al8

Minor cervical Malalignament On Static CSR

Severe Cervical Pain W/Normal Static CSR

Yes Yes Yes NA NA NA NA NA NA NA Yes* Yes Yest Yes NA NA Suggested Contraindications

Severe Cervical Tenderness W/Normal Static CSR

Flexion/Extension Injury Mechanism

Suspected Instability W/Normal Static CSR

Yes NA NA NA NA Yes Yes NA

No Yes NA NA NA Yes NA NA

NA NA Yes Yes Yes NA NA Yes

Reference

Altered Mental Status

Neurologic Abnormality

Lack Unstable Fracture On Static CSR

Emergency Medicine: Concepts & Clinical Practice 17 The Radiology of Emergency Medicine18 Neurosurgery19 Operative Orthopaedics2° American College of Radiology16 Brady et a121 * Wales LR et aJ7 Lewis LM et al8

Yes NA Yes NA NA Yes Yes Yes

Yes NA NA NA Yes Yes Yes Yes

NA NA NA NA NA NA Yes Yes

Yes/No, Issue directly addressed in individual source; NA, issue not directly addressed in individual reference; *additional radiographic indications/contraindicationswere reported;21 1-after negative AP & thin section tomography.

injury if the patient manifests significant muscular spasm, is stable, and lacks obvious fracture or dislocation on the 3-view trauma series. 22 Our study raises several interesting points. One is that all of the patients requiring invasive surgical stabilization had abnormalities on both static and dynamic CSR. This finding suggests that the most clinically significant and specific indication for the use of FE films may be abnormal static CSR. Another interesting finding is the very small incidence of clinically significant (ie, requiring invasive stabilization) isolated cervical ligamentous injuries (4 out of 451 patients in whom FE films were ordered), or 4 patients in 5 years at a level one trauma center. Such an injury is quite rare, and any investigative study aimed at further exploring the use of FE films must be quite large. Several additional issues remain unanswered. One of the difficulties in performing a study of the use of FE films in the diagnosis of isolated ligamentous injury is the actual determination of its frequency of occurrence. In fact, we could not determine the incidence or prevalence of such an injury. Based on this fact and our own study findings, we assume that isolated ligamentous injury is rare. The second question involves the indications for FE films. Answers to these first 2 questions require a large, multicenter, prospective study. A final question in studying this issue is what is the gold standard for its identification. Perhaps the answer to this will be MRI as has been suggested by several recent studies. This study has several limitations, including its retrospective nature and convenience sample structure. Patients underwent FE views at the discretion of the treating physicians and therefore represent a selected subpopulation

of blunt trauma cases with neck pain. This "referral bias" certainly limits the study results applicability to the general blunt trauma population. Also, such an issue limits any true comments on true indications other than the finding that patients with an abnormal static series were more likely to have a surgically correctable lesion on FE views. Lastly, outcome issues were not addressed. Patients with an initially negative static and dynamic CSR may have harbored "occult" injury: "occult" in that the initial series of CSR films were falsely negative. We did not determine the adequacy of dynamic CSR in our population. Patients may certainly have limited cervical motion due to pain; such limited flexion and extension could result in a false-negative radiographic examination.

CONCLUSION

The blunt trauma patient with neck complaints and an abnormal static CSR was more likely to have an abnormal dynamic CSR showing a cervical injury requiring stabilization. Patients with a normal static cervical spine series who manifested dynamic abnormality all were treated noninvasively with collar support. Further, all patients in the study underwent FE radiography without direct medical supervision and did not have complication, suggesting that the appropriate protocol executed by radiology technologists is both safe and adequate. A large prospective study using the appropriate gold standard is required to determine the incidence of isolated ligamentous cervical spine injury and proper indications for FE views.

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