Spine Trauma and Spinal Cord Injury

Key Points

•

Patients with spinal pain and spine fractures should receive a thorough neurologic examination to look for spinal cord injury.

•

Spine fractures are associated with a high incidence of concurrent noncontiguous spine fractures and spinal cord injuries.

•

The National Emergency X-radiography Utilization Study criteria or the Canadian Cervical-Spine Rule criteria can be used to identify low-risk patients who do not need cervical spine imaging.

•

Imaging with plain films versus computed tomography of the cervical spine should be based on the pretest probability of a significant injury and the irradiation risk with computed tomography.

•

Spinal shock, or transient physiologic transection of the spinal cord as a result of trauma, is different from neurogenic shock, which is physiologic sympathectomy of the upper spinal cord leading to peripheral vasodilation.

•

Patients with a spinal cord injury caused by blunt trauma are often given high-dose corticosteroids within 8 hours of injury, although such therapy is controversial.

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 ).

Table 75.1

Individual Spinal Sensory Dermatomes, Motor Function, and Reflex Arcs

SPINAL LEVEL SENSORY DISTRIBUTION MOTOR FUNCTION REFLEX

C2 Occiput

C3 Thyroid cartilage

C4 Suprasternal notch Spontaneous respiration

C5 Infraclavicular area Shoulder shrugging Biceps

C6 Thumb Elbow flexion Triceps

C7 Index finger Elbow extension

C8 Little finger Finger flexion (with T1)

T4 Nipple line

T10 Umbilicus

L1 Inguinal ligament Hip flexion (with L2)

L2 Medial thigh Hip flexion

L3 Medial thigh Hip adduction

L4 Medial foot Hip abduction Patellar

L5 Web space between big toe and second toe Foot dorsiflexion

S1 Lateral foot Foot plantar flexion (with S2) Achilles

S2 Perianal area (with S3, S4) Foot plantar flexion

S3-4 Perianal area Rectal sphincter tone

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 ( ).

Table 75.2

Physical Examination Findings Associated with Vertebral Fractures and Spinal Cord Injuries

INJURY PHYSICAL EXAMINATION AREA ASSOCIATED FINDINGS

Vertebral fracture

SpineTenderness of the neck and/or back. Examine the entire spine because vertebral fractures may occur in multiples.

Neurologic See spinal cord injury below.

Chest

Thoracic spine fractures: Check for chest tenderness, unequal breath sounds, and arrhythmia, which are suggestive of an associated intrathoracic injury or myocardial contusion.

Abdomen/pelvis

Thoracolumbar and lumbar spine fractures: Check for abdominal or pelvic tenderness. For instance, up to 50% of patients with a transverse process fracture 7 and 33% of patients with a Chance fracture 8 have concurrent intraabdominal pathology. A transverse area of ecchymosis on the lower abdominal wall (seat belt sign) increases the chance of an abdominopelvic injury.

Extremity Thoracolumbar and lumbar spine fractures: Check for calcaneal tenderness because 10% of calcaneal fractures are associated with a low

INJURY PHYSICAL EXAMINATION AREA ASSOCIATED FINDINGS

thoracic or lumbar fracture. Mechanistically, these areas are fractured as a result of axial loading.

Spinal cord injury

Neurologic, motor (anterior column)

Assess motor function on a scale of 0 to 5 (see Table 75.3). motor level is defined as the most caudal segment with at least 3/5 strength. Injuries to the first eight cervical segments result in tetraplegia (previously known as quadriplegia); lesions below the T1 level result in paraplegia.

Neurologic, sensory (spinothalamic tract)

Assess sensory function via pinprick and light touch on the following scale: 0 = absent; 1 = impaired; 2 = normal. The sensory level is defined as the most caudal segment of the spinal cord with normal sensory function. The highest intact sensory level should be marked on the patient's spine to monitor for progression.

Neurologic, sensory (dorsal column)

Assess vibratory sensory function on a scale of 0 to 2 by using a tuning fork over bony prominences. Assess position sense (proprioception) by flexing and extending the great toe.

Neurology, deep tendon reflexOn a scale of 0 to 4, assess the deep tendon reflexes in the upper (biceps, triceps) and lower (patellar, Achilles) extremities (see Table 75.4).

Anogenital

Assess rectal tone, sacral sensation, signs of urinary or fecal retention or incontinence, and priapism. Also check the anogenital reflexes: an anal wink (S2-S4) is present if the anal sphincter contracts in response to stroking the perianal skin area. The bulbocavernosus reflex (S3-S4) is elicited by squeezing the glans penis or clitoris (or pulling on an inserted Foley catheter), which results in reflexive contraction of the anal sphincter.

Head-to-toe examination

A spinal cord injury may mask a patient's ability to perceive and localize pain. Imaging of high-risk

INJURY PHYSICAL EXAMINATION AREA ASSOCIATED FINDINGS

areas, such as the abdomen, and areas of bruising or swelling may be required to exclude occult injuries.

Table 75.3

Graded Assessment of Motor Function

GRADE ASSESSMENT ON PHYSICAL EXAMINATION

0 No active contraction

1 Trace visible or palpable contraction

2 Movement with gravity eliminated

3 Movement against gravity

4 Movement against gravity and resistance

5 Normal power

Table 75.4

Graded Assessment of Deep Tendon Reflexes

GRADE ASSESSMENT ON PHYSICAL EXAMINATION

0 Reflexes absent

1 Reflexes diminished but present

2 Normal reflexes

3 Reflexes increased

4 Clonus present

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.

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

AdvantagesLess 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.

Older and Osteopenic Patients

Patients older than 65 years old and those taking corticosteroids on a long-term basis are probably osteopenic. They can sustain spinal fractures with mild trauma, such as a fall from a standing position, and often exhibit minimal associated pain. Specifically, patients older than 65 years have an increased risk for cervical spine fracture (relative risk of 2.09). 16 In addition, acute back pain in chronic corticosteroid users is correlated with 99% specificity for a spinal compression fracture. 17 Thus, imaging should be performed in these potentially osteopenic patients in the setting of neck or back pain.

Clinical Clearance of the Cervical Spine

Not all patients require cervical spine imaging. To clinically clear a cervical spine, the patient's neck should be reevaluated for tenderness. First, unfasten the cervical collar. Next, palpate the posterior aspect of the patient's neck while applying the other hand to the patient's forehead to prevent spontaneous and reflexive head lifting. In the absence of significant midline tenderness, remove your hands and instruct the patient to actively lift the head off the gurney and place the neck through a range of motion by looking right, left, caudad, and cephalad. Do not assist the patient.

If the patient is able to move spontaneously and easily without pain or neurologic symptoms, the patient's neck is considered to be “clinically cleared” and the collar may be removed.

 Facts and Formulas

Ten percent of spinal fractures have a second noncontiguous fracture along the vertebral spine.

Ten percent of patients with a calcaneal fracture have an associated thoracic or lumbar fracture.

The most commonly fractured cervical spine level is C2, especially in the elderly. Approximately 20% of computed tomography–confirmed burst fractures in the thoracic

and lumbar spine appear as wedge fractures on plain film radiography. 18

High-dose methylprednisolone is administered as a 30-mg/kg bolus and then as a 5.4-mg/kg/hr infusion for 24 hours (if started within 3 hours of injury) or for 48 hours (if started within 8 hours of injury).

Consider early endotracheal intubation in spinal cord injury patients with a negative inspiratory force of less than −25 cm H 2O or a vital capacity of less than 15 mL/kg.

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) *

INJURY MECHANISM STABILITY FIGURE COMMENTS

Atlantooccipital dislocation

Flexion Unstable 75.7, A

Often instantly fatal More common in children because of small, horizontally oriented occipital condyles Dislocation can be anterior (most common), superiorly distracted, or posterior

Anterior atlantoaxial dislocation

Flexion Unstable 75.7, B

Associated with rupture of the transverse ligament Most commonly occurs in patients with rheumatoid arthritis and ankylosing spondylitis from ligament laxity Widening of the predental space seen on lateral plain films

Jefferson fracture (C1 burst fracture)

Axial compression

Unstable 75.7, C

33% with associated C2 fracture Low incidence of neurologic injury because of a wide C1 spinal canal Usually involves fractures of both the anterior and posterior C1 arches, often with 3 or 4 fracture fragments Complication: transverse ligament rupture, especially if the C1 lateral masses are ≥7 mm wider than expected (MRI recommended); vertebral artery injury (CT angiography recommended)

C1 posterior arch fracture

Extension Stable 75.7, C

An associated C2 fracture (occurs 50% of time) makes a posterior arch fracture unstable On plain films, no displacement of lateral masses on the odontoid view and no prevertebral soft tissue swelling, unlike a Jefferson burst fracture

INJURY MECHANISM STABILITY FIGURE COMMENTS

C2 dens fracture Flexion Variable 75.7, D

Type I (stable): Avulsion of the dens with an intact transverse ligament Type II (unstable): Fracture at the base of the dens; 10% have an associated rupture of the transverse ligament—MRI provides a definitive diagnosis of ligament rupture Type III (stable): Fracture of the dens extending into the vertebral body

Hangman's fracture (C2 spondylolisthesis)

Extension Unstable 75.7, E

Bilateral C2 pedicle fractures At risk for disruption of the PLL, C2 anterior subluxation, and C2-C3 disk rupture Low risk for spinal cord injury because of C2 anterior subluxation, which widens the spinal canal

Extension teardrop fracture

Extension Unstable 75.7, F

Small triangular avulsion of the anteroinferior vertebral body at the insertion point of the ALL Occurs most frequently at the C2 level but can occur in the lower cervical spine Complication: central cord syndrome as a result of the ligamentum flavum buckling during hyperextension Requires CT differentiation from a very unstable flexion teardrop fracture (see “flexion teardrop fracture” in Table 75.7)

* Listed in progressive order from the occiput, to C1, to C2.

Table 75.7

Classic Lower Cervical Spine Injury Patterns (C3-C7)

INJURY MECHANISM STABILITY FIGURE COMMENTS

Articular mass fracture

Flexion-rotation

Stable 75.8, AAssociated with transverse process and vertebral body fractures Uncommon

Burst fractureAxial compression

Stable 75.8, B

Compressive fracture of the anterior and posterior vertebral body Intact ALL and PLL Complication: spinal cord injury because of a retropulsed vertebral body fragment (especially anterior cord syndrome)

Clay shoveler's (spinous

Flexion Stable 75.8, B Spinous process fracture from forceful neck flexion Most commonly occurs in the lower cervical levels,

INJURY MECHANISM STABILITY FIGURE COMMENTS

process) fracture

usually C7 Not associated with neurologic injury

Extension teardrop fracture

Extension Unstable 75.7, F Most commonly occurs at C2 See Table 75.6

Facet dislocation, bilateral

Flexion Unstable 75.8, C

Significant anterior displacement (>50%) of the spine when bilateral inferior facets displace anterior to the superior facets below At risk for injuring the disk, vertebral arteries, and spinal cord

Facet dislocation, unilateral

Flexion-rotation

Stable 75.8, DUsually causes 25-50% anterior displacement of the spine Complication: vertebral artery injury (CT angiography recommended)

Flexion teardrop fracture

Flexion and axial loading

Unstable 75.8, E

One of the most unstable fractures in the lower cervical spine because it involves both columns Fracture and anterior displacement of the anteroinferior vertebral body (appears similar to an extension teardrop fracture except that it is much more unstable) Unique findings for flexion (versus extension) teardrop fractures include same-level fractures and displacement of posterior structures Rupture of both ALL and PLL complexes Usually occurs at C5 or C6 Can result from diving into shallow water or a football tackling injury Often associated with spinal cord injury and tetraplegia

Subluxation, anterior

Flexion Unstable 75.8, F

Anterior slipping of a vertebra over another Ruptured PLL such that the anterior and posterior vertebral lines are disrupted Complication: vertebral artery dissection (CT angiography recommended) May be evident only during flexion views by conventional radiography when the interspinous distance widens and the vertebral body subluxates anteriorly

Transverse process fracture

Lateral flexion Stable 75.8, A

Complication: vertebral artery injury because it travels within the transverse foramina (CT angiography recommended); associated cervical radiculopathy and brachial plexus injuries in 10% of cases

INJURY MECHANISM STABILITY FIGURE COMMENTS

Wedge fracture Flexion Stable 75.8, G

Compression fracture of only the anterosuperior vertebral body end plate Disruption of the anterior vertebral line Intact posterior vertebral body and posterior vertebral line

Table 75.8

Classic Thoracic and Lumbar Spine Injury Patterns

INJURY MECHANISM STABILITY FIGURE COMMENTS

Wedge fracture

FlexionStable, usually

75.8, G

Most common fracture in the thoracic spine Isolated anterior column fracture Disruption of the anterior vertebral line with an intact posterior vertebral line (classic) Maintain a low threshold to obtain spine CT for differentiation of a wedge from a burst fracture (up to 22% of burst fractures appear to have an intact posterior vertebral line)

Burst fracture

Axial loading Variable 75.8, B

Fracture of the anterior and middle columns Disruption of the anterior and posterior vertebral lines (classic) 65% have associated spinal cord injury because of middle column compromise

Chance fracture

Flexion-distraction

Unstable 75.9, A

Fracture through the anterior, middle, and posterior columns, progressing from posterior to anterior Usually located at the T12-L2 junction Classically caused by a lap belt hyperflexion mechanism in a motor vehicle collision 33-89% associated with intraabdominal injury Spinal cord injury is uncommon because of the distraction mechanism

Transverse process fracture

Stable 75.9, B Most common fracture in the lumbar spine Classically has a vertical fracture orientation A horizontal transverse process fracture orientation suggests a distraction injury (Chance fracture) More than 50% of transverse process fractures are missed by conventional radiography and detected on spine CT Clinically insignificant, but a risk factor for other injury patterns 50% associated with an intraabdominal injury 30% associated with a pelvic fracture (especially an L5

INJURY MECHANISM STABILITY FIGURE COMMENTS

transverse process fracture) L2 transverse process fracture is associated with renal artery thrombosis

Fracture-dislocation

Compression or distraction

Unstable 75.9, C

Significant spinal misalignment and vertebral column discontinuity Fracture through the anterior, middle, and posterior columns Extremely high incidence of spinal cord injury

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.

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.

Thoracic and Lumbar Spine Injuries

Similar to patients undergoing cervical spine assessment, low-risk patients may selectively be cleared clinically without radiographic imaging. Although no large studies of thoracic and lumbar spine injuries equivalent to the NEXUS and CCR projects have been conducted, recommendations can be extrapolated from the relevant literature.

Based on the NEXUS criteria, patients with (1) significant back pain or tenderness, (2) clinical evidence of drug- or alcohol-related intoxication, (3) lower extremity neurologic deficits, (4) Glasgow Coma Scale score lower than 15, or (5) a distracting injury cannot be cleared clinically for a thoracic or lumbar fracture. Patients with alcohol intoxication, for example, should not be cleared clinically until they are sober and found to fulfill no other high-risk criteria.

Furthermore, based on the CCR criteria and the American Healthcare Research and Quality “red flag” indications for imaging, injured patients who are (1) older than 65 years with any degree of back pain or tenderness, (2) are receiving chronic corticosteroid therapy, or (3) have a history of vertebral disease should undergo radiography.

Classic patterns of thoracic and lumbar spine injuries are shown in Table 75.8.

Classification of Spinal Cord Injuries

Complete Injury

A spinal cord injury is classified as physiologically complete if the patient has no demonstrable motor or sensory function below the level of injury. During the first few days following injury, this diagnosis cannot be made with certainty because of the possibility of concurrent spinal shock.

Incomplete Injury

A spinal cord injury is incomplete if motor function, sensation, or both are partially present below the level of the injury. Signs of an incomplete injury may include (1) the presence of any sensation or voluntary movement in the lower extremities or (2) evidence of sacral sparing. Signs of sacral sparing include perianal sensation, voluntary anal sphincter contraction, and voluntary great toe flexion.

Specific incomplete spinal cord injuries include central and anterior cord syndromes, Brown-Séquard syndrome, and conus medullaris syndrome. Patients with these syndromes have certain characteristic patterns of neurologic injury with distinct findings on physical examination.

Central Cord Syndrome

Central cord syndrome is the most common spinal cord syndrome and is usually due to neck hyperextension. Trauma to the central portion of the cord results in injury to the medially located corticospinal motor tracts of the upper extremities. As a result, the upper extremities are

predictably and disproportionately weaker than the lower extremities. Many patients exhibit bladder dysfunction (e.g., urinary retention) and varying degrees of sensory loss. Elderly patients are more at risk for central cord syndrome because of underlying cervical spondylosis, a thickened ligamentum flavum, or both.

Anterior Cord Syndrome

Anterior cord syndrome results from blunt or ischemic injury to the anterior spinal cord. Affected patients have a complete and usually bilateral motor deficit below the level of the injury along with loss of pain and temperature sensation a few levels below the lesion. Typically, posterior column function is preserved.

Brown-Séquard Syndrome

Brown-Séquard syndrome is a rare hemicord injury that is usually associated with penetrating trauma. Patients have crossed sensory and motor deficits: ipsilateral loss of motor function and position sense below the level of the lesion and contralateral loss of pain and temperature sensation one to two levels below the injury.

Conus Medullaris Syndrome

Conus medullaris syndrome results from injury to the spinal cord with occasional involvement of the lumbar nerve roots. It results in areflexia of the bladder, bowel, and lower extremities. Patients may exhibit perianal numbness. Motor and sensory deficits in the lower limbs vary.

Cauda Equina Syndrome

Although cauda equina syndrome is not a direct spinal cord injury because the cauda equina is composed entirely of peripheral nerves (lumbar, sacral, and coccygeal nerve roots), it still requires emergency neurosurgical intervention. Clinical findings include asymmetric sensory loss, weakness of the lower extremities, urinary retention or incontinence, decreased rectal tone, and saddle anesthesia.

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.

Neurogenic Shock

Neurogenic shock results from a sympathectomy-induced reduction in blood pressure, heart rate, cardiac contractility, and cardiac output. Overly vigorous fluid resuscitation can be hazardous because of compromised cardiac output. Judicious use of vasopressors such as phenylephrine hydrochloride, dopamine, and norepinephrine is often indicated. Significant bradycardia should be treated hemodynamically with atropine.

Systolic blood pressure lower than 80 mm Hg is rarely due to neurogenic shock alone, and other causes of shock, primarily from hemorrhage, must be excluded. It should never be assumed that hypotension is due to spinal shock until hemorrhage is excluded.

Corticosteroid Therapy for Spinal Cord Injury

Though controversial, treatment of blunt spinal cord injury with high-dose methylprednisolone is common. This therapeutic recommendation is based on the findings of the National Acute Spinal Cord Injury Study (NASCIS), which demonstrated improved neurologic function in patients receiving high-dose corticosteroids within 8 hours of injury. Improved neurologic function, however, was defined as a modest gain in motor scores but not functional improvement. In NASCIS, a loading dose of 30 mg/kg of methylprednisolone administered over a 15-minute period was followed by an infusion of 5.4 mg/kg/hr and continued for 24 hours (in patients treated within 3 hours of injury) or 48 hours (in patients treated 3 to 8 hours after injury). 20 21 No benefit was found when steroids were administered more than 8 hours after injury.

Steroid therapy is not indicated for penetrating injuries and has not been adequately studied in children younger than 13 years or in patients with cauda equina or spinal root injury.

Finally, systemic corticosteroid therapy is not benign. Complications of steroid therapy include gastrointestinal hemorrhage and wound infection in patients treated with corticosteroid infusions for 24 hours and higher rates of severe sepsis and severe pneumonia in those treated for 48 hours. The use of steroids for blunt traumatic spinal cord injury is far from the standard of care. 22 More research is needed to verify or refute this controversial therapy.

Surgical Management of Spinal Cord Injury

Timely reduction of the displaced spinal column plus decompression of the spinal cord has been associated with recovery from otherwise devastating spinal cord injuries. 23 The optimal timing of surgery following a spinal injury remains controversial. Some argue for immediate surgery, whereas others advocate delayed surgery because of the initial posttraumatic swelling. The sole absolute indication for immediate surgery is progressively worsening neurologic status in patients with spinal fracture-dislocations who initially have incomplete or absent neurologic deficits. 24

In a series of patients with traumatic central cord syndrome, those who underwent early surgery (<24 hours after injury) and had an underlying disk herniation or fracture-dislocation exhibited significantly greater overall motor improvement than did those who underwent late surgery (>24 hours after injury). 25 Unfortunately, early decompressive surgery does not uniformly improve outcome following spinal cord injury.

 Priority Actions

Provide pain control. Maintain full spinal precautions until the spine can be cleared radiographically or

clinically. If intubating a trauma patient, an assistant should provide in-line cervical spine

immobilization until the cervical spine can be assessed more definitively at a later time. Perform a careful initial neurologic examination, especially in patients who are about to

undergo sedation or neuromuscular blockade.

If a spinal fracture is suspected or detected, evaluate for associated injuries: o •

For the cervical spine, examine for associated head and facial injuries.

o •

For the thoracic spine, examine for rib fractures and pulmonary, cardiac, diaphragmatic, and mediastinal injuries.

o •

For the lumbar spine, examine for intraabdominal injuries, pelvic fractures, and calcaneal fractures.

o •

For all spinal levels, examine for spinal cord injury.

Obtain urgent spine imaging if a fracture or spinal cord injury is suspected. Obtain emergency magnetic resonance imaging of the spine if a spinal cord injury is

suspected. Consider administering corticosteroids if an adult patient has sustained blunt spinal

trauma and exhibits neurologic deficits within 8 hours of injury.

Tips and Tricks

Prolonged immobilization on a rigid backboard is uncomfortable for the patient and places the patient at risk for aspiration and early pressure sores. Aim to remove the backboard as soon as possible and ideally within 2 hours of patient arrival. A standard hospital gurney provides adequate thoracic and lumbar stability.

Perform serial neurologic examinations on patients with suspected or known spinal injuries to document neurologic improvement or deterioration. Neurologic deterioration involving the cervical and upper thoracic levels may require empiric endotracheal intubation for impending respiratory failure.

Once a spinal injury is detected, carefully reexamine the entire cervical, thoracic, and lumbar spine. Obtain plain films or computed tomography scans of any levels with pain or tenderness because of the high risk for a second spinal injury.

When performing “clinical clearance” of a patient's cervical spine or obtaining flexion-extension cervical spine plain films, do not passively range the neck for the patient. This may cause an iatrogenic spinal injury. Pain with active movement will prevent the patient from overranging the neck.

 Red Flags (Pitfalls)

Failure to identify occult injuries in hypoesthetic areas. For example, in a patient with a midthoracic sensory level deficit, occult intraabdominal injuries may be hidden because the abdomen may be insensate.

Failure to consider a spinal cord injury in a patient with normal radiographic and computed tomographic (CT) findings.

Failure to repeat plain films or obtain CT imaging when plain film radiographs of the cervical, thoracic, or lumbar spine are inadequate.

Failure to exclude other causes of hypotension in a trauma patient before assuming that it is neurogenic shock. A search for occult blood loss should first be done.

Failure to consider a distracting injury, particularly fractures, as a reason for a patient's ability to localize neck and back pain.

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.

 Documentation

Document neck and back tenderness, along with the neurologic examination, in all trauma patients.

In spinal cord injury patients, mark the initial level of sensory deficit to monitor progression of the patient's neurologic status.

For patients with neurologic deficits, perform and document the bulbocavernosus reflex and sacral-sparing examination to assess for spinal shock.

Suggested Readings1Bracken MB, Shepard MJ, Holford TR,

et al

: Administration of methylprednisolone for 24 or 48 hours or tirilazad mesylate for 48 hours in the treatment of acute spinal cord injury. Results of the Third National Acute Spinal Cord Injury Randomized Controlled Trial. National Acute Spinal Cord Injury Study. JAMA 1997; 277: 1597-1604

2Hoffman 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: 94-99

3Stiell 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: 2510-2518