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cord ischemia.

Brown-Séquard syndrome results from hemisection of the cord, usually due to a penetrating trauma. In its pure form, the syndrome consists of ipsilateral motor loss (corticospinal tract) and loss of position sense (dorsal column), associated with contralateral loss of pain and temperature sensation beginning one to two levels below the level of injury (spino-thalamic tract). Even when the syndrome is caused by a direct penetrating injury to the cord, some recovery is usually achieved.

MorpHoLogy

Spinal injuries can be described as fractures, fracture- dislocations, spinal cord injury without radiographic abnormalities (SCIWORA), and penetrating injuries. Each of these categories can be further described as stable or unstable. However, determining the stability of a particular type of injury is not always simple and, indeed, even experts may disagree. Particularly during the initial treatment, all patients with radiographic evidence of injury and all those with neurological deficits should be considered to have an unstable spinal injury. Spinal motion of these patients should be restricted, and turning and/or repositioning requires adequate personnel using logrolling technique until consultation with a specialist, typically a neurosurgeon or orthopedic surgeon.

specific types of spiNAl

iNjuRies

Spinal injuries of particular concern to clinicians in the trauma setting include cervical spine fractures, thoracic spine fractures, thoracolumbar junction fractures, lumbar fractures, penetrating injuries, and the potential for associated blunt carotid and vertebral vascular injuries.

CerViCaL spine FraCtUres

Cervical spine injuries can result from one or a combination of the following mechanisms of injury: axial loading, flexion, extension, rotation, lateral bending, and distraction.

Cervical spine injury in children is a relatively rare event, occurring in less than 1% of cases. Of note, upper cervical spine injuries in children (C1–C4) are almost twice as common as lower cervical spine injuries. Additionally, anatomical differences, emotional

distress, and inability to communicate make evaluation of the spine even more challenging in this population. (See Chapter 10: Pediatric Trauma.)

Specific types of cervical spine injuries of note to clinicians in the trauma setting are atlanto-occipital dislocation, atlas (C1) fracture, C1 rotary subluxation, and axis (C2) fractures.

Atlanto-Occipital Dislocation

Craniocervical disruption injuries are uncommon and result from severe traumatic flexion and distraction. Most patients with this injury die of brainstem destruction and apnea or have profound neurological impairments (e.g., ventilator dependence and quadriplegia/tetraplegia). Patients may survive if they are promptly resuscitated at the injury scene. Atlanto-occipital dislocation is a common cause of death in cases of shaken baby syndrome.

Atlas (C1) Fracture

The atlas is a thin, bony ring with broad articular surfaces. Fractures of the atlas represent approximately 5% of acute cervical spine fractures, and up to 40% of atlas fractures are associated with fractures of the axis (C2). The most common C1 fracture is a burst fracture (Jefferson fracture). The typical mechanism of injury is axial loading, which occurs when a large load falls vertically on the head or a patient lands on the top of his or her head in a relatively neutral position. Jefferson fractures involve disruption of the anterior and posterior rings of C1 with lateral displacement of the lateral masses. The fracture is best seen on an open-mouth view of the C1 to C2 region and axial computed tomography (CT) scans (nFIGURE 7-4).

These fractures usually are not associated with spinal cord injuries; however, they are unstable and should be initially treated with a properly sized rigid cervical collar. Unilateral ring or lateral mass fractures are not uncommon and tend to be stable injuries. However, treat all such fractures as unstable until the patient is examined by a specialist, typically a neurosurgeon or orthopedic surgeon.

C1 Rotary Subluxation

The C1 rotary subluxation injury is most often seen in children. It can occur spontaneously, after major or minor trauma, with an upper respiratory infection, or with rheumatoid arthritis. The patient presents with

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a persistent rotation of the head (torticollis). With this injury, the odontoid is not equidistant from the two lateral masses of C1. Do not force the patient to overcome the rotation, but restrict motion with him or her in the rotated position and refer for further specialized treatment.

Axis (C2) Fractures

The axis is the largest cervical vertebra and the most unusual in shape. Thus it is susceptible to various fractures, depending on the force and direction of the impact. Acute fractures of C2 represent approximately 18% of all cervical spine injuries. Axis fractures of note to trauma care providers include odontoid fractures and posterior element fractures.

Odontoid Fractures

Approximately 60% of C2 fractures involve the odontoid process, a peg-shaped bony protuberance that projects upward and is normally positioned in contact with the anterior arch of C1. The odontoid process is held in place primarily by the transverse ligament. Type I odontoid fractures typically involve the tip of the odontoid and are relatively uncommon. Type II odontoid fractures occur through the base of the dens and are the most common odontoid fracture

(n FIGURE 7-5). In children younger than 6 years of age,

the epiphysis may be prominent and resemble a fracture at this level. Type III odontoid fractures occur at the base of the dens and extend obliquely into the body of the axis.

Posterior Element Fractures

A posterior element fracture, or hangman’s fracture, involves the posterior elements of C2—the pars inter- articularis (nFIGURE 7-6). This type of fracture is usually

caused by an extension-type injury. Ensure that patients with this fracture are maintained in properly sized rigid cervical collar until specialized care is available.

Fractures and Dislocations (C3 through C7)

The area of greatest flexion and extension of the cervical spine occurs at C5–C6 and is thus most vulnerable to injury. In adults, the most common level of cervical vertebral fracture is C5, and the most common level of subluxation is C5 on C6. Other injuries include subluxation of the articular processes (including unilateral or bilateral locked facets) and fractures of the laminae, spinous processes, pedicles, or lateral masses. Rarely, ligamentous disruption occurs without fractures or facet dislocations.

The incidence of neurological injury increases significantly with facet dislocations and is much more severe with bilateral locked facets.

tHoraCiC spine FraCtUres

Thoracic spine fractures may be classified into four broad categories: anterior wedge compression injuries, burst injuries, Chance fractures, and fracture-dislocations.

Axial loading with flexion produces an anterior wedge compression injury. The amount of wedging usually is quite minor, and the anterior portion of the vertebral

SPECIFIC TYPES OF SPINAL INJURIES 137

n FIGURE 7-4 Jefferson Fracture. Open-mouth view radiograph

showing a Jefferson fracture. This fracture involves disruption of both the anterior and posterior rings of C1, with lateral displacement of the lateral masses.

n FIGURE 7-5 Odontoid Fracture. CT view of a Type II odontoid

138 CHAPTER 7 n Spine and Spinal Cord Trauma

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body rarely is more than 25% shorter than the posterior body. Due to the rigidity of the rib cage, most of these fractures are stable.

Burst injury is caused by vertical-axial compression. Chance fractures are transverse fractures through the vertebral body (nFIGURE 7-7). They are caused by

flexion about an axis anterior to the vertebral column and are most frequently seen following motor vehicle crashes in which the patient was restrained by only an improperly placed lap belt. Chance fractures can be associated with retroperitoneal and abdominal visceral injuries.

Due to the orientation of the facet joints, fracture- dislocations are relatively uncommon in the thoracic and lumbar spine. These injuries nearly always result from extreme flexion or severe blunt trauma to the spine, which causes disruption of the posterior elements (pedicles, facets, and lamina) of the vertebra. The thoracic spinal canal is narrow in relation to the spinal cord, so fracture subluxations in

the thoracic spine commonly result in complete neurological deficits.

Simple compression fractures are usually stable and often treated with a rigid brace. Burst fractures, Chance fractures, and fracture-dislocations are extremely unstable and nearly always require internal fixation.

tHoraCoLUMbar jUnCtion FraCtUres

(t11 tHroUgH L1)

Fractures at the level of the thoracolumbar junction are due to the immobility of the thoracic spine compared with the lumbar spine. Because these fractures most often result from a combination of acute hyperflexion and rotation, they are usually unstable. People who fall from a height and restrained drivers who sustain severe flexion with high kinetic energy transfer are at particular risk for this type of injury.

The spinal cord terminates as the conus medullaris at approximately the level of L1, and injury to this part of the cord commonly results in bladder and bowel dysfunction, as well as decreased sensation and strength in the lower extremities. Patients with thoracolumbar fractures are particularly vulnerable to rotational movement, so be extremely careful when logrolling them. (See Logroll video on MyATLS

mobile app.)