Cervical Spine Fracture Evaluation Workup

Radiographic evaluation is indicated in the following:

• Patients who exhibit neurologic deficits consistent with a cord lesion

• Patients with an altered sensorium from head injury or intoxication

• Patients who complain about neck pain or tenderness

• Patients who do not complain about neck pain or tenderness but have significant distracting injuries

The literature has examined the need for C-spine imaging in patients at low risk for unstable fracture or ligamentous injury. The Canadian C-Spine Rules (CCR) and the National Emergency X-Radiography Utilization Group (NEXUS) criteria allow clinicians to "clear" low-risk patients of C-spine injury, obviating the need for radiography. Additionally, a model was developed specifically for injured children. ^{[2, 9, 18, 40]}

To be clinically cleared using the CCR, a patient must be alert (GCS 15), must not be intoxicated, and must not have a distracting injury (eg, long bone fracture, large laceration). The patient can be clinically cleared provided the following criteria are met:

• The patient is not high risk (age >65 y or dangerous mechanism or paresthesias in extremities).

• A low risk factor that allows safe assessment of range of motion exists. This includes simple rear end motor vehicle collision, seated position in the ED, ambulation at any time post trauma, delayed onset of neck pain, and absence of midline cervical spine tenderness.

• The patient is able to actively rotate the neck 45 degrees left and right.

The NEXUS criteria state that a patient with suspected C-spine injury can be cleared provided the following are true:

• No posterior midline cervical spine tenderness is present.

• No evidence of intoxication is present.

• The patient has a normal level of alertness.

• No focal neurologic deficit is present.

• The patient does not have a painful distracting injury.

Both studies have been prospectively validated as being sufficiently sensitive to rule out clinically significant C-spine pathology. The CCR were shown to be more sensitive than NEXUS criteria (99.4% sensitive vs 90.7%), and rates of radiography were lower with CCR (55.9% vs 66.6%). ^[41] Debate continues as to which criteria are more useful and are easier to apply.

A survey of 76 trauma care physicians found that altered mental state, intoxication, and distracting injury were the most important contraindications to cervical spine clearance in children. Regarding imaging, 54% considered adequate plain imaging to be 3-view cervical spine radiographs (anterior-posterior, lateral, and odontoid), whereas 30% considered CT to be the most sensitive modality for detecting unstable cervical spine injuries. ^[42]

A standard trauma series is composed of 5 views: cross-table lateral, swimmer's, oblique, odontoid, and anteroposterior.

According to the World Federation of Neurosurgical Societies (WFNS), angiography has been considered the gold standard for vertebral artery injury after cervical trauma, but it is difficult and time consuming to perform. CTA, using multislice machines, has been shown to identify the injury with a sensitivity of 100%. ^[43]

Cross-table lateral view

Approximately 85-90% of cervical spine injuries are evident in the lateral view, making this the most useful view from a clinical standpoint.

A technically acceptable lateral view shows all 7 vertebral bodies and the cervicothoracic junction. One should approach analysis of this view methodically to avoid missing significant pathology.

Check alignment of the cervical spine by following 3 imaginary contour lines. (See the image below.)

The first line connects the anterior margins of all vertebrae and is referred to as the anterior contour line. The second line should connect the posterior aspects of all vertebrae in a similar way and is referred to as the posterior contour line. The third line should connect the bases of the spinous processes and is referred to as the spinolaminar contour line.

Each of these lines should form a smooth lordotic curve. Suspect bony or ligamentous injury if disruption is seen in the contour lines.

An exception occurs in young children, who, because of immature muscular development, may have a benign pseudosubluxation in the upper cervical spine. An imaginary straight line should connect the points bisecting the base of the spinous processes of C1, C2, and C3. In pseudosubluxation, these imaginary points should not be displaced more than 2 mm in front of or behind the straight line.

Check individual vertebrae thoroughly for obvious fracture or changes in bone density. Areas of decreased bone density are seen in patients with osteoporosis, osteomalacia, or osteolytic lesions and may represent weak areas predisposed to injury. Areas of increased bony density may be seen with osteoblastic lesions or may represent compression fractures of an acute nature.

Look for soft tissue changes in predental and prevertebral spaces. The predental space, also known as the atlantodental interval, is the distance between the anterior aspect of the odontoid and the posterior aspect of the anterior arch of C1. This space should be no larger than 3 mm in an adult and 5 mm in a child. Suspect transverse ligament disruption if these limits are exceeded.

Prevertebral space extends between the anterior border of the vertebra to the posterior wall of the pharynx in the upper vertebral level (C2-C4) or to the trachea in the lower vertebral level (C6).

At the level of C2, prevertebral space should not exceed 7 mm.

At the level of C3 and C4, it should not exceed 5 mm, or it should be less than half the width of the involved vertebrae.

At the level of C6, the prevertebral space is widened by the presence of the esophagus and the cricopharyngeal muscle. At this level, the space should be no larger than 22 mm in adults or 14 mm in children younger than 15 years.

Children younger than 24 months may exhibit a physiologic widening of the prevertebral space during expiration; therefore, images should be obtained in small children during inspiration to assess prevertebral space adequately.

If the prevertebral space is widened at any level, a hematoma secondary to a fracture is the most likely diagnosis.

Check for fanning of the spinous processes. This is evident as an exaggerated widening of the space between 2 spinous process tips and suggests posterior ligamentous disruption.

Check for an abrupt change in angulation greater than 11 degrees at a single interspace. This suggests bony injury with possible ligamentous involvement.

Swimmer's view

Occasionally, it is impossible to fully visualize all 7 cervical vertebrae and, more important, the cervicothoracic junction in a true lateral image.

Failure to fully visualize these areas has resulted in patient morbidity and successful malpractice litigation against emergency physicians.

A swimmer's view, or a transaxillary view, adequately exposes these areas for scrutiny.

Oblique view

This view also is considered a laminar view because most pathologic conditions assessed on it manifest with some disruption in the normal overlapping appearance of the vertebral laminae.

The normal structural appearance of the laminae is described as shingles on a roof, forming a regular elliptical curve with equal interlaminar spaces.

If interlaminar space between 2 continuous laminae is increased, suspect subluxation of the involved vertebrae.

Similarly, if the expected tiling of shingles is disrupted, suspect a unilateral facet dislocation.

A posterior laminar fracture should be evident as disruption of the body of a single shingle.

Odontoid view

This view is used to evaluate an area that is difficult to visualize in the cross-table lateral view because of shadow superimposition.

The most important structural relationship to evaluate in this view is alignment of the lateral masses of C1 with respect to the odontoid process.

Masses should be bilaterally symmetric with the dens and odontoid process and must be checked for fractures or lateral displacement.

Assess symmetry of the interspace between C1 and C2.

Anteroposterior view

This is the least useful view from a clinical standpoint.

A straight line should connect the spinous processes bisecting the cervical spine. If this is not seen, consider a rotation injury (ie, unilateral facet dislocation). Also consider a clay shoveler fracture if a spinous process appears vertically split.

The advent of readily available multidetector computed tomography (CT) has supplanted the use of plain radiography at many centers. The literature supports CT as more sensitive, with lower rates of missed primary and secondary injuries. ^[15] One series found 36% of patients with one injury on plain radiography had a second injury seen on CT only. Of these patients, 27% had a noncontiguous, anatomically distinct second injury. The same views generated by plain radiography (AP, lateral, open mouth) are generated via CT. These results are cause to reconsider guidelines for implementation of CT as a primary diagnostic test. If plain radiograph findings are negative but clinical suspicion for fracture is high, films should be followed by CT.

One study determined that CT of the cervical spine may be overused for ground-level falls. The authors suggested that, in such cases, consistent application of clinical decision rules (eg, NEXUS, CCR) would reduce both costs and radiation dose exposure if applied across all level I trauma centers. ^[44]

The American College of Orthopaedic Surgeons now recommends routine cervical spine screening via CT scan instead of plain radiography. Low-dose multidetector CT scanning has been found to be as sensitive and specific as standard dose multidetector CT scans. ^{[45, 46]}

Soft tissue injury (ie, unstable ligamentous injury) has traditionally been evaluated by flexion-extension views. Magnetic resonance imaging (MRI) is less dangerous and more sensitive for soft tissue injury than radiography. Limited availability makes familiarity with flexion-extension views essential. ^{[47, 48]}

Multidetector-row CT (MDCT) and MRI can be  complementary, and both may be necessary to identify injuries and to determine proper management. ^[49]

In a 5-year retrospective study of polytrauma patients who underwent MDCT, signs of significant ligament injury on CT at the craniocervical junction were identified as increased basion dens interval and widened facet joints. In the subaxial cervical spine, more than 50% subluxation of a facet joint and obscured posterior paraspinal fat pad were indicators of significant ligament injury. ^[6]

An association between cervical spine fractures and thoracolumbar spine fractures has been identified in victims of motor vehicle collisions (MVCs). Based on this finding, it is recommended that any MVC patient found to have a cervical spine fracture should undergo complete spine imaging. ^[4]

One study supported findings in the literature that C1-C3 spine injuries have an increased association with vertebral artery injury. The authors noted, however, that CT angiography of the head and neck ordered off protocol had a low likelihood of being positive and that strict adherence to protocols for CT angiography of the head and neck can reduce costs and decrease unnecessary exposure to radiation and contrast medium. ^[50]

In a study by Goode et al, the National Emergency X-Radiography Utilization Study (NEXUS) criteria (NC) were compared with computed tomography (CT) as the gold standard to evaluate cervical spine (C-spine) fractures in elderly blunt trauma patients. According to findings, the authors suggested that NEXUS criteria are not an appropriate assessment tool when applied to severe blunt trauma patients, particularly in the elderly population, who have more missed injures than younger patients. They concluded that CT should be used in all blunt trauma patients regardless of whether they meet NEXUS criteria. ^[51]

Small and associates explored the use of a conventional neural network for CT cervical spine fracture detection and found that the convolutional neural network holds promise for both prioritizing worklists and assisting radiologists in cervical spine fracture detection on CT. Clinicians must gain an understanding of the strengths and weaknesses of the convolutional neural network before they can successfully incorporate it into clinical practice. Further refinements in sensitivity will improve the diagnostic usefulness of the convolutional neural network. ^[52]

A retrospective cross-sectional study sought to develop a clinical tool to identify patients who must undergo CT for evaluation of cervical spine fracture when treated at a hospital in which CT scanning is not available. Diagnostic imaging in developing countries has limitations. Also, CT scanning is not universally available 24 hours a day and is not cost-effective. This study included patients over 16 years of age with suspected cervical spine injury who underwent CT scanning in the ED. Study authors viewed independent factors (ie, high-risk mechanism of injury, paraparesis, paresthesia, limited range of motion of the neck, and associated chest or facial injury) as good predictors of C-spine fracture and developed predictive model and prediction scores via multivariable logistic regression analysis. Researchers concluded that patients with a clinical prediction score of 1 or greater should undergo CT for evaluation of cervical spine fracture. ^[53]