Chapter 9: Cervical Spine Trauma

Prompt diagnosis of cervical spine (C-spine) injuries is imperative to provide early treatment and prevent secondary spinal cord injury. Motor vehicle collisions account for the majority of spinal cord injuries followed by falls and acts of violence (i.e., gunshot wounds).¹ Cervical spine injuries are found in 2% to 3% of blunt trauma patients that undergo imaging.² The cervical spine is the most common location in the spine to be injured, accounting for upward of 60% of cases.^1,3 Unfortunately, a delay in diagnosis occurs in one-quarter of cases. Approximately 3% of malpractice claims are related to fractures of the spine, and these claims account for almost 10% of dollars paid.

The upper cervical spine consisting of the occiput, C1 (atlas), and C2 (axis) is unique from the remainder of the cervical spine. It is designed to allow for rotation of the head. The C1 vertebra is a ring structure that articulates with the occiput. The C2 vertebra is composed of a body with a bony projection (dens) that goes through the anterior portion of the ring of C1. The dens is stabilized by both the transverse and alar ligaments (Fig. 9–1). The transverse ligament is located along the posterior surface of the dens, attaching on either side of C1. Injury to this ligament may be catastrophic to the patient in the form of atlantoaxial instability and a high cervical cord lesion.

The lower cervical spine can be divided into two columns, where disruption of an entire column is required to alter stability.⁴ The anterior column consists of the anterior and posterior longitudinal ligaments and the vertebral body. The posterior column comprises the pedicle, lamina, articular facet joints, and ligamentum flavum.

Imaging

Not all patients with a traumatic source of neck pain will require imaging. Two groups have attempted to safely reduce the rate of imaging of the cervical spine in the setting of trauma based on the absence of high-risk criteria.^5,6 The National Emergency X-Radiography Utilization Study (NEXUS) group consisting of 34,069 patients identified five criteria that were 99.6% sensitive in excluding a clinically significant cervical spine injury (Table 9–1). The Canadian C-spine rule detected 100% of 151 clinically significant C-spine injuries in 8924 patients. In this rule, to be considered for exclusion from needing C-spine radiographs, patients must have a Glasgow Coma Scale of 15 and have no high risk features (age greater than 65, dangerous mechanism, or extremity paresthesias). Next, low risk factors are assessed. In patients with a low risk factor (simple rear-end MVC, sitting in ED, ambulatory at any time, delayed onset of neck pain, or absence of midline C-spine tenderness) neck rotation is tested. If they are able to actively rotate the neck 45 degrees to the left and right, no radiographs are needed.⁶

When NEXUS criteria were applied to the Canadian C-Spine Rule data set, the sensitivity of NEXUS criteria was 92.7%.⁷ In a prospective cohort study (in Canadian emergency departments), the Canadian C-spine Rule had higher sensitivity (99.4% vs. 90.7%) and specificity (45.1% vs. 36.8%) versus the NEXUS criteria and would have led to a reduction in radiography rates, although patient populations were different between the two studies.⁸

Plain radiographs have historically been used as a screening test for cervical spine injury. The typical trauma series includes an anteroposterior (AP), an open-mouth (odontoid), and a lateral view. The plain radiographs detect approximately 65% to 75% of injuries and should include the C7-T1 junction because a high number of injuries occur at C7.^9–12 In the polytrauma unconscious patient, the sensitivity and adequacy of plain films is reduced and has little role, making computed tomography (CT) the imaging test of choice.¹² Flexion-extension radiographs are controversial and not performed routinely, especially when CT and magnetic resonance imaging (MRI) are available.

The interpretation of plain radiographs is addressed in this chapter when discussing each injury; however, the clinician should have a systematic approach to avoid missing important injuries. Before beginning, assess the adequacy of the films, specifically whether the open-mouth view allows visualization of the dens and lateral masses and whether the lateral view demonstrates all of the cervical vertebrae and the top of T1. Next, consider the alignment of the vertebrae on the lateral view (Fig. 9–2). Look closely for any fractures of the vertebral bodies or posterior bony structures. Loss of height of a vertebral body suggests a compression fracture. An abnormal angle between vertebral bodies suggests an unstable fracture. Finally, evaluate the prevertebral soft tissues and the predental space (Fig. 9–3).

Because plain radiographs are less sensitive and frequently inadequate at demonstrating the entirety of the cervical spine, CT scan of the cervical spine is the more common initial imaging study of choice in trauma patients. The sensitivity for detecting injuries is 97% to 100% and the specificity is 99.5%.^13–17 A negative CT scan that includes sagittal reconstructions has been shown to exclude both fracture and clinically significant ligamentous injury even in patients with persistent neck pain.¹⁸ Cervical spine immobilization can often be discontinued with a normal CT at the discretion of the physician.^12,16 In addition, when a fracture is seen on plain radiographs, CT is useful to further define the traumatic injury. MRI is useful for soft tissue, ligamentous, disk, or spinal cord injuries but is poor for detecting osseous injuries. Additional disadvantages include a high false-positive rate in trauma and obvious time and patient access constraints in the emergency setting.^12,16,17 Isolated clinically significant cervical spine or ligamentous injury with a negative CT is extremely rare.¹⁶

Spinal Cord Injury

Neurogenic shock occurs most commonly after cervical spine injury (19% of patients), followed by thoracic (7%) and lumbar (3%) injuries. Vital signs demonstrate a low systolic blood pressure (<100 mm Hg) and bradycardia (<60–80 beats/min). These abnormalities usually occur several hours after cord injury. The pathogenesis is related to loss of sympathetic tone and decreased peripheral vascular resistance. Bradycardia is present because the disruption of sympathetic activity to the heart resulting in unopposed vagal activity. Neurogenic shock should be distinguished from the term “spinal shock,” which refers to an initial loss with a gradual recovery of some neurologic function after a spinal cord injury.

Knowledge of the location of nerve tracts within the spinal cord will help the clinician understand the syndromes that occur after injury (Fig. 9–4). A patient with a complete cord syndrome will present early with flaccid paralysis and loss of sensation below the injury. Reflexes are absent and there will be no response to the Babinski test. Priapism may appear and generally lasts for a day. Within 1 to 3 days, hyperactive reflexes, a positive Babinski, and spasticity develop reflecting the upper motor neuron injury.

Incomplete cord injury is usually more challenging to diagnose. Several classic variants exist, but there is significant disparity in presentation. The anterior cord syndrome occurs in most cases from hyperflexion of the cervical spine. The anterior two-thirds of the cord are affected but the dorsal columns, controlling light touch, proprioception, and vibratory sense, are spared to a variable degree (Fig. 9–5A). Central cord syndrome is due to hyperextension injury and occurs frequently in patients with preexisting cervical degenerative joint disease. In this setting, the central portion of the cord is compressed between the ligamentum flavum and bony osteophytes. Clinically, the patient will exhibit motor impairment that is greatest in the upper extremities with variable amounts of sensory loss and bladder dysfunction (Fig. 9–5B). Finally, the Brown-Sequard syndrome is a rare condition due to unilateral loss of cord function from hemisection of the spinal cord (Fig. 9–5C). The patient will exhibit paralysis with loss of proprioception, vibration, and light touch on the side of the damage and loss of pain and temperature sensation on the contralateral side.

Treatment

Neurogenic shock should be considered in the patient with hypotension, bradycardia, and traumatic spinal cord injury once other causes of shock have been excluded. There is no consensus on the optimal treatment of neurogenic shock. Crystalloid fluid infusion and cervical stabilization may be all that is necessary in mild cases. Pressors are indicated if vascular instability persists.

In patients with blunt traumatic spinal cord injury, high-dose steroids were considered as a treatment option early postinjury.^19,20 Even within the recommended 8-hour window, steroids carry a significant incidence of complications such as sepsis and pneumonia. In addition, the evidence for the efficacy of steroids to produce a small gain in the total motor and sensory score was seen only in a post-hoc analysis. This fact increases the likelihood that a statistical difference will be found when one does not exist and generally precludes the results from being used to change clinical practice.²¹ Therefore, without compelling evidence for the efficacy of a high-dose steroid regimen, many feel that steroids should be used with caution or not at all.^22,23 Several medical societies have stated that this treatment is not a “standard of care” and recent literature recommends not using steroids in spinal cord injury as the risk of harm outweighs the potential benefit.^24,25

Classification

The cervical spine is divided into two segments for the purposes of this chapter. High cervical spine injuries are those that involve the occiput, C1, and C2. The remainder of the chapter focuses on injuries to the third through seventh cervical vertebrae. This discussion categorizes injuries based on the mechanism of injury. Clinical stability of each injury is discussed. Loss of stability refers to the inability of the spine to maintain relationships under normal physiologic loads. With instability comes the inherent risk of secondary spinal cord injury if spinal immobilization is not adhered to.

Occipitoatlantal Dissociation

This injury involves a disruption of all of the ligamentous connections between the occiput and the atlas (Fig. 9–6). The skull may be anterior, posterior, or distracted from the cervical spine. This injury is almost always fatal due to the significant amount of force required to cause it. Radiographs demonstrate displacement of the occipital condyles from the superior articulating facets of the atlas. The distance between the tip of the clivus (i.e., basion) and a line extending from the posterior cortex of C2 (basion–axial interval) should be less than 12 mm. A second measurement between the basion and the superior surface of the dens (basion–dental interval) should also be less than 12 mm. If this injury is suspected, immediate referral is indicated and any type of axial traction is to be avoided as it may increase the displacement of this highly unstable injury.

Atlantoaxial Dislocation

The most common atlantoaxial dislocation is anterior with either transverse ligament rupture or odontoid fracture. Posterior and rotatory injuries are less common. A pure transverse ligament rupture is more common in older individuals, but can also occur in young patients following trauma, most commonly a motor vehicle collision.²⁶

The clinical presentation is variable, with death common from a high-level cord compression between the odontoid and posterior arch of the atlas. Radiographs reveal an abnormal relationship between the atlas and axis. In the anterior dislocation, there is an increased distance (>3 mm) between the posterior aspect of the anterior arch of the atlas and the odontoid process. A distance between 3 and 5 mm suggests transverse ligament disruption, whereas a distance greater than 5 mm is consistent with rupture of both the transverse and alar ligaments (Fig. 9–7). Open-mouth plain radiographic views or preferably CT scan will demonstrate an odontoid fracture. Immediate consultation with a spine surgeon for stabilization and reduction is required.

Jefferson Burst Fracture

The Jefferson burst fracture is due to axial loading when the spine is neither flexed nor extended. This results in fractures of the anterior and posterior arches of C1 on the left and right (Fig. 9–8A). On plain films, prevertebral soft-tissue swelling is usually evident on the lateral view, but the fractures themselves are hard to appreciate.²⁷ The open-mouth view demonstrates displacement of the lateral masses of the atlas (Fig. 9–8B). CT scan is necessary to fully appreciate the fracture pattern (Fig. 9–8C).

Fractures of the ring of the atlas can be stable or unstable based on the integrity of its ligamentous support, specifically the transverse and alar ligaments. Displacement of the lateral masses of the atlas by a distance of 7 mm or more, seen commonly on the open-mouth view, is evidence of a ruptured transverse ligament (Fig. 9–8D). This constitutes an unstable injury in which the odontoid process can compress the spinal cord.

Jefferson burst fractures are associated with additional cervical spine fractures with an incidence of 50%. Definitive treatment consists of halo traction (Fig. 9–9).

C1 Arch Fractures

In addition to the axial loading (i.e., Jefferson burst fracture), other mechanisms can cause fractures of the C1 arch. Hyperextension can cause avulsion of the anterior tubercle of the atlas (Fig. 9–10). This injury will be seen on the lateral radiograph or CT scan and there is frequently associated soft-tissue swelling. If the avulsion consists of the entire anterior arch, then this injury may be unstable.

Hyperextension with compression can direct a force across the posterior arch of the atlas that will cause fracture at the junction of the posterior arch and the lateral mass. The lateral radiograph best demonstrates this fracture. It is seen as a vertical fracture with little or no displacement and there is no prevertebral swelling. There will be no lateral displacement of the C1 articular masses on the open-mouth view, as seen in a burst fracture. This fracture is frequently associated with other cervical spine fractures, particularly to the dens. If isolated, this fracture may be stable.

Consultation with a spine surgeon is recommended for any fracture of the C1 arch and the patient should be kept immobilized.

Odontoid Fractures

There are three types of odontoid fractures (Fig. 9–11). Type I is an avulsion of the tip of the dens at the site of attachment of the alar ligament. It is uncommon injury and is stable as long as the transverse ligament remains intact. If the patient complains of any neurologic symptoms, suspect another injury or that the transverse ligament is ruptured. Type I dens fractures may be associated with occipitoatlantal dissociation.

Type II fractures are transverse at the base of the odontoid. This fracture is unstable. Type III fractures occur through the body of the axis, often involving an articulating facet. If this fracture is displaced, it is usually unstable.

A quarter of these patients will present with neurologic deficits, whereas the majority will report a severe high cervical pain with muscle spasm made worse with any attempts at movement.

Radiographically, these injuries are best seen on CT scan, although the open-mouth view is the best plain film method to make the diagnosis (Fig. 9–12). Flexion-extension views are contraindicated, as displacement may be potentially fatal. Type II and III fractures require immediate referral for stabilization.

Hangman’s Fracture

Also referred to as traumatic spondylolisthesis of the axis, the Hangman’s fracture is a hyperextension injury of the high cervical spine that produces a fracture at the pedicles of C2 with anterior displacement of C2 on C3 (Fig. 9–13). This fracture was seen in judicial hangings, but is now more common following motor vehicle collisions and diving accidents. Although this injury is highly unstable, the patient may present without significant neurologic dysfunction because of the large diameter of the spinal canal at this level.

The forces that lead to injuries of the lower cervical spine can be used for classification and aid in the understanding of the ligamentous and bony injuries present. Flexion, flexion-rotation, extension-rotation, extension, and vertical compression all produce distinct injury patterns that are discussed below.

Flexion

Flexion Teardrop Fracture

This is an extremely unstable injury produced by severe hyperflexion and compressive forces as might occur with diving into the shallow end of a pool. The result is complete ligamentous disruption with facet joint disruption and a comminuted fracture of the vertebral body that frequently push fragments into the spinal canal (Fig. 9–14). There is a large triangular fragment off the anterior portion of the vertebral body in the shape of a teardrop that gives this fracture its name. Neurologic deficit is common, either in the form of a complete cord injury or an anterior cord syndrome. Radiographically, the anterior inferior corner fracture of the vertebral body is evident on the lateral view. The upper cervical spine is flexed and the involved vertebra is displaced and rotated anteriorly.

When this injury occurs at the C3–5 levels in a diver, the patient might present with apnea, presumed to be drowning when in fact a cervical spine injury has produced respiratory muscle paralysis. Intubation will be necessary in this circumstance and the patient will require continuous immobilization. Consultation with a spine surgeon for definitive care is emergent.

Clay Shoveler’s Fracture

This injury is a fracture of the spinous process that occurs when the head and the upper cervical vertebrae are forced into flexion against the action of the supraspinatus ligament and erector muscles. The end result is an avulsion fracture of one or more of the spinous processes of C7, C6, and T1, in that order of frequency (Fig. 9–15). This fracture is named due to its frequency in Australian clay miners in the 1930s. It is more common today after direct trauma to the spinous process or after decelerating motor vehicle collisions. Patient will complain of point tenderness over the involved area. This is a stable injury and requires analgesics and early referral.

Bilateral Facet Dislocation

Severe hyperflexion results in the rupture of the posterior ligamentous complex, which allows the superior facets to pass up and over the inferior facets, where they rest in the intervertebral foramina creating a very unstable injury. The majority of these injuries occur between C5 and C7. Patients will present with neck pain and the inability to move the head from a midline position. On examination, there is often prominence of the spinous process of the inferior vertebrae. There may be cord or nerve root compression leading to neurologic deficits. Radiographs are characterized by an anterior displacement of the superior vertebral body of at least 50% of its width (Fig. 9–16). The term perched facets refers to an incomplete bilateral dislocation where the inferior aspect of the superior facets rests on the superior aspect of the inferior facets. Emergent reduction can result in significant recovery of neurologic deficits.

Wedge Compression Fracture

This fracture occurs from forceful flexion with some mild axial compressive forces that impact the vertebral body (Fig. 9–17). The anterior portion of the superior endplate of the vertebral body fractures. Posterior structures remain intact in most cases, but their involvement makes this fracture unstable. Loss of the anterior vertebral height by more than half or multiple adjacent wedge fractures may also make this injury unstable. For this reason, these fractures should be considered unstable until proven otherwise.

Hyperflexion Sprain

This injury is also referred to as an anterior subluxation. Hyperflexion causes the posterior ligamentous structures to rupture without associated fractures (Fig. 9–18). On radiographs, there may be a widening of the spinous processes at the level of the ligamentous rupture.²⁸ Angulation of two vertebrae by more than 11 degrees is abnormal, suggests instability, and is consistent with this injury (Fig. 9–19).

Flexion-Rotation

Unilateral Facet Dislocation

Unilateral facet dislocation occurs from a combination of flexion and rotation. The joint opposite the side of rotation becomes dislocated as the superior facet moves anteriorly and superiorly above the inferior facet. In the absence of concomitant fractures, stability remains because the contralateral joint remains intact. Clinically, neck pain usually localizes to the affected side and the head is rotated away from the lesion. Nerve root impingement is frequent, but the spinal cord is rarely involved. The lateral radiograph shows the vertebral body anteriorly displaced by a distance of approximately 25% of the diameter of the vertebral body (Fig. 9–20). Treatment of this condition frequently requires open reduction and internal fixation as this injury can be very difficult to reduce by traction and may have varying degrees of ligamentous injury.²⁹

Extension-Rotation

Pillar Fracture

This fracture of the pillar of the facet joint is caused by a hyperextension and rotation mechanism (Fig. 9–21). Hyperextension brings the facet bones together and as the head rotates, a force is directed toward a single pillar that causes it to fracture. Radiographically, the AP projection will demonstrate an abnormality of the lateral column. The fracture line is usually vertical. On the lateral view, the injury is difficult to identify.³⁰ A “double-outline” sign occurs when the fracture is displaced posteriorly and causes two radiographic shadows.³¹ A tear in the anterior longitudinal ligament may also occur with this fracture. A pillar fracture is considered stable.

Pedicolaminar Fracture Separation

This injury involves unilateral fractures of the pedicle and lamina with varying degrees of displacement and disruption of the anterior longitudinal ligament and disk. The term “separation” refers to the fact that with a fracture to both the pedicle and laminae on one side, the articular pillar (i.e., facet) becomes a free-floating fragment. If the disk above and below the fractured vertebra is involved, then this becomes an unstable injury. On the AP view, there is disruption of the lateral column similar to the appearance of a pillar fracture. On the lateral radiograph, these injuries resemble a laminar or pillar fracture. Occasionally there is anterolisthesis of the involved vertebra by approximately 3 mm. CT is useful to determine the full extent of the injury (Fig. 9–22).

Extension

Hyperextension Sprain

This injury occurs from a blow to the face or forehead or, more commonly, after a rear-end motor vehicle collision. The posterior structures act as a fulcrum and the anterior longitudinal ligament and intervertebral disk rupture (Fig. 9–23). With significant ligamentous disruption, the superior vertebra can move posteriorly and compress the spinal cord. If the posterior ligamentous complex is also disrupted, dislocation may occur. On examination, there is usually pain and tenderness over the anterior muscles (i.e., sternocleidomastoid and scalenes). There may be dysphagia and hoarseness secondary to injury of the throat and esophagus. Posterior cord injury with motor loss distal to the lesion is most common. Radiographs will exhibit soft-tissue swelling. An anteriorly widened disk space may also be apparent. If this injury is suspected, CT or MRI should be used to confirm ligamentous disruption. Patients with a normal neurologic examination and negative imaging studies can be treated with analgesics and early referral. Others require immediate consultation with a spine surgeon.

Extension Teardrop Fracture

This unstable injury is similar to a hyperextension sprain, but the anterior longitudinal ligament avulses the inferior portion of the anterior vertebral body (Fig. 9–24). The triangular-shaped fragment’s height is usually higher than its width. Extension teardrop fractures are usually more common in elderly patients with osteoporosis. CT is required to evaluate the spinal canal. Consultation with a spine surgeon is indicated and the patient is kept immobilized.

Laminar Fracture

This fracture occurs most frequently in older patients with cervical stenosis. With hyperextension and compression, the lamina can fracture (Fig. 9–25). On the lateral radiograph, a vertical fracture line may be seen, but CT is more sensitive. This injury is stable, but requires cervical immobilization and referral.

Vertical Compression

Burst Fracture

Burst fractures are due to an axial load that causes a comminuted fracture of the vertebral body (Fig. 9–26). They are most common at the level of C5. Frequently, fragments displace into the spinal canal. The posterior ligament complex remains intact, but a fracture of the posterior arch is almost always present. The burst fracture appears similar to the flexion teardrop, but the anterior fragment of the body is usually larger. Immediate consultation with a spine surgeon is indicated for this potentially unstable fracture.

Cervical spine injuries represent a potentially devastating injury to the patient and a financial burden to society. Early recognition and proper stabilization of cervical injuries is paramount. CT is the initial imaging test of choice for the cervical spine in trauma patients and useful for osseous injuries. Fracture and injury pattern recognition aides in determining appropriate early consultation or referral for definitive management.