Epidemiology

The estimated annual cost of spine injuries, including inability to work and health care costs, exceeds $5 billion in the United States.¹

In the emergency department (ED), all trauma victims are screened for vertebral fractures, ligamentous disruptions, and spinal cord injuries because of the potentially devastating neurologic consequences of overlooking these injuries. Patients with a delayed diagnosis of spinal fracture are 7.5 times more likely to sustain secondary neurologic deficits.² Neurologic deficits from spinal cord injury may be subtle and can easily be missed if not specifically evaluated. Adding to these difficulties, plain film radiographs of the spine, though an adequate screening tool for other fractures, can miss 23% to 42% of cervical spinal fractures^3,4 and 13% to 50% of lumbar fractures.^5,6

Pathophysiology

In the setting of spinal trauma, the bone, ligaments, spinal cord, and vascular structures may be injured. Anatomically, the vertebral bony spine can be divided into structural columns. The cervical spine is traditionally divided into two columns—anterior and posterior. The anterior column consists of the load-bearing vertebral bodies, intervertebral disks, anterior longitudinal ligament, and posterior longitudinal ligament (Fig. 75.1). The posterior column consists of the more posterior structures, including the pedicles, laminae, and transverse and spinous processes (Fig. 75.2).

Fig. 75.1 Bony anatomy of a typical lower cervical vertebra (C3-C7): superior axial view with the anterior aspect oriented upward and the posterior aspect oriented downward.

Fig. 75.2 Bony anatomy of a typical thoracic and lumbar vertebra (T1-L5): superior axial view with the anterior aspect oriented upward and the posterior aspect oriented downward.

In contrast, the thoracic and lumbar vertebral spines are divided into three columns based on the modified Denis model—anterior, middle, and posterior (Fig. 75.3). The anterior column consists of the anterior longitudinal ligament, the anterior two thirds of the vertebral body, and the intervertebral disk. The middle column consists of the posterior longitudinal ligament, the posterior third of the vertebral body, and the intervertebral disk. Any disruption of the middle column predisposes a patient to significant spinal cord injury because the middle column abuts the spinal canal. The posterior column consists of the remaining posterior structures.

Fig. 75.3 Schematic diagram illustrating the lateral view of the anatomic columns of the cervical and thoracic/lumbar spine.

Note that the cervical spine’s anterior column is composed of the same structures as the thoracic/lumbar spine’s anterior and middle columns.

The C1 and C2 vertebrae are anatomically unique (Fig. 75.4). C1 (atlas) is a ring-link structure without a vertebral body. It articulates superiorly with the occipital condyles. This articulation allows 50% of normal neck flexion and extension. C2 (axis) projects the dens superiorly to articulate with C1. The transverse ligament tethers the dens to the anterior arch of C1. This atlantoaxial articulation allows 50% of normal neck rotation left and right.

Fig. 75.4 Bony anatomy of the upper cervical spine (C1 and C2): posterolateral view.

The C1 lateral masses articulate with the occipital condyles. The C2 dens projects cephalad, articulates with the C1 anterior arch, and is stabilized by the C1 transverse ligament.

The spinal cord spans from the foramen magnum to the L1 level, whereupon the spinal cord tapers into the conus medullaris and cauda equina, a collection of peripheral lower lumbar and sacral nerve roots. Because the spinal cord is thickest in the cervical spine, there is relatively less spinal canal space in the cervical levels than in the thoracic or lumbar spine. Thus spinal cord injuries occur more frequently with cervical spine trauma than with thoracic or lumbar spine trauma. The neurologic dermatomes can help localize the injury (Table 75.1).

The vertebral arteries branch off the subclavian arteries and course superiorly within the transverse foramina of C2 to C6. These arteries then merge to form the basilar artery.

Presenting Signs and Symptoms

Patients with vertebral fractures usually have significant midline spinal tenderness on palpation. High-risk findings include spinal soft tissue swelling, ecchymosis, and step-off misalignment of the spine. Pain radiating along a dermatomal distribution suggests an associated radiculopathy. Thoracic spine fractures are uncommon because the articulating ribs provide stability to the spinal column; however, the thoracolumbar junction (encompassing the T10 to L2 vertebral levels) is commonly injured because the spine curvature changes from the kyphotic thoracic spine to the lordotic lumbar spine.

Patients with spinal cord injuries may have a spectrum of findings ranging from subtle neurologic deficits to grossly obvious paralysis. Spinal cord injuries should be suspected in any trauma victim who complains of neck or back pain, especially pain exacerbated by movement. Neurologic symptoms suggesting spinal cord injury include numbness, tingling, paresthesias, focal weakness, and paralysis. Other worrisome symptoms include urinary or fecal incontinence and urinary retention. Unconscious patients and those with impaired consciousness secondary to intoxication may harbor occult spinal cord injuries. Physical examination should focus on the spine and areas where associated injuries may occur (Tables 75.2 and 75.4).

Table 75.2 Physical Examination Findings Associated with Vertebral Fractures and Spinal Cord Injuries

Table 75.3 Graded Assessment of Motor Function

Table 75.4 Graded Assessment of Deep Tendon Reflexes

Spinal shock is a neurologic phenomenon resulting from physiologic transection of the spinal cord. It results in flaccid paralysis and loss of reflexes below the level of the spinal cord lesion. Spinal shock is temporary, commonly lasting for 24 to 48 hours, although it can persist for weeks. Patients suffering from spinal shock may appear (clinically) to have a complete spinal cord injury only to “miraculously” recover once the spinal shock has passed. Termination of spinal shock is identified by return of segmental reflexes; anogenital reflexes are the earliest to recover.

Neurogenic shock may occur in patients with cervical or high thoracic spinal cord injuries. It is a neurocardiovascular phenomenon resulting from impairment of the descending sympathetic pathways in the spinal cord. As a result, vasomotor tone is lost and visceral and peripheral vasodilation and hypotension ensue. Diminished sympathetic innervation to the heart also occurs and results in relative bradycardia despite the presence of hypotension.

Differential Diagnosis and Medical Decision Making

Indications for Cervical Spine Imaging

In the year 2000, in the hope of reducing the number of low-risk patients undergoing cervical spine plain film radiography, a multicenter study by the National Emergency X-radiography Utilization Study (NEXUS) group validated a set of five low-risk criteria for determining which patients do not require radiographic imaging if all the criteria are met (Box 75.1). This clinical decision tool demonstrated a sensitivity of 99.6% and a specificity of 12.9% for detecting clinically significant cervical spine fractures. It was thus extrapolated that 4309 (12.6%) of the 34,069 patients enrolled could have avoided plain film radiography.⁹

Box 75.1

NEXUS Low-Risk Criteria for a Cervical Spine Injury

A patient does not require cervical spine radiographic imaging if all five of the following low-risk conditions are met:

1. No posterior midline neck pain or tenderness

2. No focal neurologic deficit

3. Normal level of alertness

4. No evidence of intoxication

5. No clinically apparent, painful distracting injury*

NEXUS, National Emergency X-radiography Utilization Study.

From Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. N Engl J Med 2000;343:94-9.

^* Defined as a condition thought by the clinician to be producing pain sufficient to distract patients from a second (neck) injury.

Following development of the NEXUS criteria, the Canadian Cervical-Spine Rule (CCR) was developed (Fig. 75.5). The validated sensitivity and specificity for this decision rule were 99.4% and 45.1%, respectively.¹⁰

Fig. 75.5 Canadian Cervical-Spine Rule (CCR) algorithm for clinical clearance of the cervical spine.

The green box signifies a low-risk, negative work-up and clinical cervical spine clearance. Orange boxes signify a moderate-risk condition, and the red box signifies a high-risk condition, both of which require plain film radiography. ED, emergency department; GCS, Glasgow Coma Scale; RR, respiratory rate; SBP, systolic blood pressure.

(Data from Stiell IG, Clement CM, McKnight RD, et al. The Canadian C-Spine Rule versus the NEXUS low-risk criteria in patients with trauma. N Engl J Med 2003;349:2510-8.)

The CCR study excluded the following subjects: patients younger than 16 years; patients with an abnormal Glasgow Coma Scale score, abnormal vital signs, injuries more than 48 hours old, penetrating trauma, paralysis, and history of vertebral disease; patients seen previously for the same injury; and pregnant patients. Because these cases were not studied, the CCR guidelines should not be applied to such patients.

Choosing the Imaging Modality to Evaluate the Cervical Spine (Fig. 75.6)

When patients have at least one high-risk criterion for a spinal fracture, imaging begins with either plain films or computed tomography (CT) scans. The pros and cons of both imaging approaches are listed in Table 75.5.

Fig. 75.6 Diagnostic algorithm for a patient with neck pain resulting from blunt trauma.

CCR, Canadian Cervical-Spine Rule; CT, computed tomography; MRI, magnetic resonance imaging; NEXUS, National Emergency X-radiography Utilization Study.

Table 75.5 Advantages and Disadvantages of Plain Film Imaging and Computed Tomography of the Cervical Spine

	PLAIN FILM RADIOGRAPHY	COMPUTED TOMOGRAPHY
Advantages	Less irradiation of the thyroid, breast, and lens Can be performed at the bedside	98% sensitivity in detecting fractures More cost-effective than plain films Less delay in patient management, especially if the patient is already going to CT scanner for imaging of another body part
Disadvantages	Only 53% sensitivity in detecting fractures Three-view films are inadequate >50% of the time, especially films of the cervicocranial and cervicothoracic junction Inefficient use of radiology personnel, who are often repeating films because of image inadequacy A suspicious fracture or one detected on plain films requires additional evaluation by CT for confirmation and further delineation	More irradiation of the thyroid, breast, and lens Requires the patient to be hemodynamically stable because of being transported out of the emergency department to the CT scanner

Patients with symptoms suggestive of a spinal cord injury should undergo CT and magnetic resonance imaging (MRI) of suspicious areas of the spine. Although plain films and CT do not directly reveal spinal cord injuries, they may supply indirect evidence of such injuries. Spinal cord injury without radiographic abnormality (SCIWORA) is a traumatic myelopathy in which no abnormalities can be identified on plain films or CT.

Computed Tomography

With increasing evidence in the literature showing that CT is much more sensitive (98%) than plain film radiography (53%) in detecting cervical spine fractures, future recommendations will probably recommend cervical spine CT as the first-line diagnostic approach for most patients because of the neurologic significance of a missed cervical spine injury.¹¹ Conventional radiography is especially difficult to interpret in the high cervical spine (occiput, C1, C2) and cervicothoracic junction (C6, C7, T1), where coincidentally most cervical spine fractures occur.¹² It is important to obtain sagittal CT reconstructions, in addition to the traditional axial views, to adequately assess spinal alignment.

Cost analyses have shown that cervical spine CT scans are actually less expensive than conventional radiography in high-risk patients. These studies factored personnel time, delays in patient management while obtaining films, and the neurologic sequelae of initially missing a cervical spine injury. Cost savings are especially evident if the patient is already undergoing CT imaging of other body parts, such as head scanning for a closed head injury. With multidetector scanners being more readily available, an additional cervical spine scan would add less than 5 minutes of scan time at a relatively small cost.¹³

The risk for cancer from irradiation serves as the major deterrent against universally performing CT in all patients with neck trauma. It is estimated that up to 2% of cancers in the United States are attributable to CT studies.¹⁴ The thyroid gland, breast tissue, and lens are exposed to especially high levels of radiation in cervical spine CT, thus placing the patient at high risk for the development of thyroid cancer, breast cancer, and cataracts. Patients receive an effective dose of 0.2 millisievert (mSv) and 6 mSv for cervical spine plain films and CT, respectively. In contrast, the effective dose of a posteroanterior and lateral chest radiograph is just 0.1 mSv.¹⁵ The overall lifetime carcinogenic risk from CT imaging, however, varies depending on the patient’s age at the time of irradiation. Younger patients have greater risk, partly because they have more years of life left for the development of cancer. Furthermore, children are more radiosensitive. If irradiated after 40 years of age, the risk reaches its nadir, with an estimated lifetime attributable risk for death from cancer of less than 0.2%.¹⁴

Because of such concerns for radiation exposure, low-risk patients should undergo conventional radiography. Only patients with radiographic evidence of an injury on plain films should subsequently undergo CT scanning. For moderate- to high-risk patients, cervical spine CT should be the first-line imaging modality, especially for patients scheduled for CT scanning of another body part.

Flexion-Extension Plain Film Radiography

A normal cervical CT image adequately excludes a cervical spine fracture but cannot sufficiently evaluate ligamentous instability. In patients who have sustained significant flexion, extension, or rotational injury to the neck and have persistent neck pain, ligamentous stability should be assessed within 10 days either in the ED or by a neurosurgeon or orthopedic spine specialist.

In the ED, patients who are awake and alert and can actively flex and extend their neck 30 degrees may undergo flexion-extension plain film radiography to evaluate for spinal stability. Vertebral body subluxation or focal widening of the spinous processes suggests an unstable ligamentous injury. Because no serious adverse outcomes have resulted from voluntary neck movement by an awake, alert patient without neurologic deficits, manual manipulation of the patient’s neck should be avoided during flexion-extension radiography.

Many acutely injured patients have such severe associated cervical muscle spasms that they have limited neck mobility. As a result, flexion-extension films are often inadequate, and these patients should be immobilized in a semirigid cervical collar (e.g., a Philadelphia or Miami J collar) and undergo delayed flexion-extension plain film radiography after 7 to 10 days, when the cervical muscle spasm diminishes.

Magnetic Resonance Imaging

MRI is the best available modality for detection and characterization of spinal cord injury, but it is less sensitive than CT for cervical spine fractures. In an acute trauma patient with potential spinal injury, indications for emergency MRI include (1) complete or incomplete neurologic deficits suspicious for a spinal cord injury, (2) deterioration of spinal cord neurologic function, and (3) signs of unstable ligamentous injury. Abnormal MRI findings may include the presence of spinal canal compromise, disk herniation, and spinal cord edema or hemorrhage.

Classic Fracture Patterns (Tables 75.6 to 75.8; Figs. 75.7 to 75.9)

Cervical Spine Injuries

Based on the NEXUS study of 818 patients with cervical spine injury, fractures occurred most commonly at the level of C2 (24% of all fractures), C6 (20%), and C7 (19%). Anatomically, the most commonly fractured part of the cervical spine was the vertebral body, which accounted for 30% of fractures at the C3 to C7 levels. It was more common than fractures of the spinous process (21%), lamina (16%), and articular process (15%). Subluxations occurred most commonly at the C5-C6 (25%) and C6-C7 (23%) levels.¹⁹

Table 75.6 Classic Upper Cervical Spine Injury Patterns (C1-C2)^*

Table 75.7 Classic Lower Cervical Spine Injury Patterns (C3-C7)

Table 75.8 Classic Thoracic and Lumbar Spine Injury Patterns

Fig. 75.7 A, Cross-sectional sagittal view of anterior atlantooccipital dislocation with associated spinal cord injury. B, Posterolateral view of anterior atlantoaxial dislocation from rupture of the transverse ligament. C, Posterolateral view of a C1 Jefferson burst fracture through the anterior and posterior arch and an isolated C1 posterior arch fracture. D, Posterolateral view of the three types of C2 dens fractures. E, Sagittal view of a hangman’s fracture with bilateral C2 pedicle fracture. PLL, Posterior longitudinal ligament. F, Sagittal view of a C2 extension teardrop fracture. ALL, Anterior longitudinal ligament.

Fig. 75.8 A, Superior axial view of an articular pillar fracture and transverse process fracture. B, Sagittal view of a C4 burst fracture and C5 clay shoveler’s (spinous process) fracture. C, Sagittal view of bilateral C4 facet dislocation. D, Sagittal view of unilateral C4 facet dislocation. E, Sagittal view of a C5 teardrop fracture. F, Sagittal view of C4 anterior subluxation. G, Sagittal view of a C5 wedge fracture.

Fig. 75.9 A, Sagittal view of an L2 Chance (flexion-distraction) fracture. B, Superior axial view of a transverse process fracture in a typical lumbar spine. C, Sagittal view of an L1-L2 fracture-dislocation injury, which is at high risk for a spinal cord injury because of discontinuity of the spinal canal.

Classification of Spinal Cord Injuries

Treatment

Prehospital and ED management should include protection of the spine and spinal cord until injuries can be identified or excluded. A rigid backboard should typically be removed promptly from beneath cooperative patients because a calm person can maintain spinal column neutrality. Extended use of a rigid backboard is associated with complications such as back pain, respiratory impairment, aspiration, and decubitus ulcers.

In-Line Immobilization of the Cervical Spine

During the initial resuscitation phase of trauma victims, patients with a potential cervical spine injury may require endotracheal intubation before a definitive diagnosis can be made. By preventing neck hyperextension during direct laryngoscopy, in-line cervical spine immobilization during intubation maintains cervical spine neutrality (Fig. 75.10).

Fig. 75.10 In-line cervical spine immobilization during endotracheal intubation.

Standing to the patient’s side, the assistant uses both hands to stabilize the neck to prevent hyperextension.

Follow-up, Next Steps in Care, and Patient Education

Most patients with traumatic spinal fractures are admitted to the hospital because they fulfill at least one of four admission criteria: (1) intractable pain, (2) fracture involvement of more than one column, (3) a functionally unstable fracture pattern, and (4) the presence or potential for development of a spinal cord injury.

Patients who can be discharged home include those with normal neurologic function and (1) an isolated, stable posterior column fracture (spinous process, transverse process) in the cervical, thoracic, or lumbar spine or (2) a stable wedge fracture in the thoracic or lumbar spine.

Patients with confirmed or suspected spinal cord injury should be scheduled for early consultation with a neurosurgeon or orthopedist. This may require transfer of the patient to a spine specialty center.

The level of the spinal cord injury, associated neurologic deficits, and other traumatic injuries will determine whether the patient should be admitted to the intensive care unit, neurosurgical observation unit, or general ward. Circular beds, rotating frames, and serial inflation devices are used to protect the patient from pressure sores.

Discharged patients without a fracture or spinal cord injury require only conservative management. Discharged patients with a stable spinal fracture require only conservative management with or without an immobilization device, such as a cervical collar or thoracolumbar sacral orthosis back brace. Soft collars and back braces are not recommended because they predispose patients to stiffness of the neck and back, respectively.

Discharged patients with persistent neck pain who are still at risk for an unstable ligamentous injury should wear a semirigid cervical collar (e.g., Philadelphia or Miami J collar) for 7 to 10 days until adequate flexion-extension plain films can be obtained. Discharge instructions should include information about the warning signs of spinal cord injury.