Surgical Management of Cervical Spinal Column Injuries

The timing of a surgical intervention remains debated. Data are accumulating in support of early (<3 days) surgery. Safety, decreased morbidity, shorter length of stay, and lower rates of pneumonia have been documented. There is no consistent evidence to show improved neurologic outcome.

A. Occiput C1 to C2 injuries

• Occipital C1 injuries are an uncommon but often missed injury. Otherwise known as atlantooccipital dislocation, these typically cause a disruption between the occipital condyles and C1. Patients who survive typically exhibit lower cranial neuropathies, mono/para/quadraplegia, and respiratory dysfunction, although 20% may have normal exams. Craniocervical subarachnoid blood or cervical prevertebral edema can provide an early clue to the diagnosis. Treatment involves craniocervical fusion with internal fixation.
• C1 to C2 injuries, which are common, are frequently missed because of the relatively complex anatomy of the C1-C2 junction and the difficulty in obtaining a full set of films in the multiply injured patient. The bony odontoid fractures can be divided into types I, II, and III (Fig. 18-4).
  • Type I fractures are oblique fractures through the upper portion of the odontoid process that can be managed with a rigid cervical collar. These are rare and often confused with os odontoidium, an isolated bony ossicle with smooth margins and no osseous connection to the body of C2. Os odontoidium likely represents an acquired nonunion of C2 secondary to prior trauma. This stable fracture can be managed with observation.
  • Type II fractures are those that occur at the base of the dens. These fractures are considered to be unstable in the acute setting, although most can be managed with external stabilization (rigid cervical collar or halo-vest device). Surgical intervention should strongly be considered in patients over 50 years old, after failure to achieve anatomic alignment with external fixation, with >5 mm dens displacement, or with significant comminution. Fractures with posterior displacement provide increased morbidity as they may impinge on the spinal cord. Surgical options include an odontoid screw, posterior fixation incorporating a Gallie-or Brooks-type construct, and transarticular screws. Airway management is critical in these patients
    

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    as upper airway swelling and subsequent respiratory compromise can occur (Fig. 18-5).

    Figure 18-4. Drawing of types I, II, and III odontoid fractures.

  • Type III fractures extend from the odontoid into the vertebral body of C2. They generally have a better healing rate than type II fractures with external fixation, and rarely need surgery.
• Jefferson fractures occur when an axial load is placed on the head. The C1 bone, which is circular in nature, is forced apart. Fractures occur anteriorly or posteriorly. Stability depends on the integrity of the transverse ligament as described below. A fracture with evidence of ligamentous disruption can be treated with a halo orthosis for 3 months or a C1-C2 fusion. Stable fractures can be treated with a rigid cervical collar for 2 to 3 months.
• It is important to consider that the main ligament stabilizing the dens within the ring of C1 is the transverse ligament. This ligament keeps the dens in close approximation to the ring of C1. The space between the posterior aspect of the ring of C1 and the anterior border of the dens is called the atlantodens interval. This space should not exceed 3.5 mm in the adult (Fig. 18-6).
  • The ligament can be torn whenever the ring of C1 is fractured. The amount of medial-lateral displacement of the ring of C1 can be measured on AP radiographs or CT reconstructions. Normally, the C1 lateral masses do not overlap the C2 vertebral body. Should the combined amount of lateral mass overlap of C1 on C2 exceed 6.9 mm, consider the transverse ligament to be torn and the C1-C2 area unstable (Fig. 18-7). MRI can also identify ligamentous injury or avulsion.
• Hangman's fracture refers to spondylolisthesis of the C2 pedicle. This type of fracture is also unstable and requires external fixation with a collar or halo vest, or rarely, internal fixation. Anterior C2-C3 fusion or posterior C1-C3 fusion should be
  

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  considered in cases of severe angulation, C2-C3 disc disruption, fracture/dislocation, or failure to achieve anatomic alignment with external fixation.

  Figure 18-5. Radiograph type II odontoid fracture.

B. C3 to C7 injuries

• Most of the C3 to C7 injuries can be diagnosed from a lateral film using the three lines to determine alignment and stability. On flexion and extension views, no >3.5 mm of listhesis should be seen between two vertebrae and no > 11 degrees of angulation between vertebral bodies, as measured at the adjoining endplates. The spinous process distances should be symmetric. CT will define the bone anatomy and MRI will better show the lig-amentous injury, cord anatomy, and disc pathology. In most injuries, both studies should be obtained. In all injuries requiring traction, delay in treatment reduces the chance of nonoperative reduction.

  Figure 18-6. Lateral radiograph demonstrating excessive atlantodens interval.

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• A common type of injury involves unilateral and bilateral facet injuries. These injuries include both fractures of the facet joints and injury to the capsules with resultant “perched” facets. Both types of injuries are noted on plain films and CT. The presence of 25% subluxation of one vertebra on another can represent a unilateral facet fracture or dislocation. The CT scan appearance of this fracture
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• has the appearance of “opposing hamburger buns” (Fig. 18-8). Subluxation of 50% generally means that a bilateral facet injury has occurred. Patients with these injuries should have MRI to diagnose any disc herniation that could interfere with reduction of the two vertebral bodies, potentially causing a neurologic catastrophe if the disc compromises the cord during reduction. Those patients may need anterior discectomy before reduction.

  Figure 18-7. C1 fracture with overhanging of the C1 lateral masses as seen on anteroposterior plain film (A) and axial computed tomography scan (B).

• Generally, unilateral and bilateral facet dislocations are reduced in tong or halo traction under close supervision by the spine surgeon. Awake reduction in a stable, alert patient with no distracting injury is both feasible and preferred. The reduction can also be performed intraoperatively with electrodiagnostic monitoring. A prereduction plain film or CT should be obtained to provide baseline anatomy. MRI should be obtained prior to reduction to rule out a ruptured cervical disc. Unilateral facet fractures can be stable, with pure bony injuries handled by halo-vest immobilization. An irreducible injury, ligamentous injury, >20% subluxation, or spinal cord compression necessitates anterior or posterior surgical fixation and possible decompression.
• Bilateral facet injuries are unstable because the spinal canal is generally severely compromised. Closed reduction with traction may be unsuccessful. Intraoperative reduction and surgical stabilization is the treatment method of choice if awake reduction fails. Once again, MRI is essential prior to reduction to prevent cord injury from a traumatically herniated disc.

C.

Burst fractures generally occur as a result of flexion or axial loading. The columns may appear well aligned at first glance on the lateral radiograph. Generally noted is an expansion of the prevertebral space and loss of vertebral height. The CT scan will show the vertebral comminution which can cause canal compromise and subsequent neurologic deficit. Fracture compression of 40% or more and subluxation of 20% or more indicate definitive instability. These will require surgical stabilization but should have gentle traction or collar immobilization during studies and before surgery.

D.

Teardrop fractures must be differentiated from the less ominous extension injury with a small fragment off the anterior cortex of the vertebral body. The true teardrop injury is highly unstable; CT will show the sagittal split in the vertebral body. MRI will often demonstrate an early spinal cord contusion. Most of these patients are neurologically impaired and will need surgery to stabilize the neck and decompress the spinal cord.

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Figure 18-8. Preoperative axial computed tomography scan demonstrating a unilateral jumped and locked facet fracture and dislocation (A). The left jumped facet has the appearance of two opposing hamburger buns (arrow). Anteroposterior (B) and lateral (C) radiographs demonstrating the instrumented fusion using lateral mass screws and rods with interspinous wiring and bone grafting.

E. Spinal cord injuries without radiographic abnormality (SCIWORA)

A number of patients will appear to be neurologically impaired without fractures or liga-mentous injuries noted on initial radiographic studies. Generally, patients in this group are at the ends of the age spectrum. Young patients are susceptible to this type of injury because of the elasticity of their ligaments. In the older patient, underlying degenerative or congenital cervical stenosis is usually found. Mild hyperflexion or hyperextension injuries will cause spinal cord compression without bony fracture. Early spinal cord changes are often noted on the MRI.

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A central cord-type injury is often the result in these types of injuries. Although some of these patients will slowly recover, a number will need surgical decompression of the spinal cord to promote recovery. Conservative therapy involves a rigid cervical collar and activity restriction for 2 to 3 months followed by flexion-extension films.

F.

Ankylosing spondylitis is an inflammatory arthropathy that affects the spine and sacroiliac joints. Care of these patients is extremely difficult and should be guided by a spine specialist to avoid iatrogenic injury. The ligaments and intervertebral discs become calcified and fuse to form a “bamboo spine” that often results in a flexion contracture. The rigid and weakened bone, which is prone to bleed, fractures easily. Fractures often occur in the low cervical region, and can be difficult to identify on plain radiographs. Frequently, the underlying deformity is not known, positioning is difficult and dangerous for imaging studies, and these patients can deteriorate neurologically because of malposition of the neck and their propensity to develop epidural hematomas. Excessive extension must be avoided. Prepositioning x-rays are essential to determine the baseline anatomy.

VIII. Surgical Management of Thoracolumbar Spinal Column Injuries

A.

Compression fractures typically involve the anterior column only. CT will differentiate a one-column injury from a more unstable two-column injury. The lateral film will show the loss of vertebral height (Fig. 18-9). Greater than 40% loss of height can signal an unstable fracture requiring surgical treatment. This amount of wedging associated with posterior tenderness generally signals a ligamentous injury to the posterior column. Multiple compression fractures can be unstable and should be watched closely. Higher fractures (T1-T9) require much more

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energy to fracture because of rib cage stability and are associated with more serious injury. Multiple rib fractures and sternal fractures are associated with instability. Most T10-L5 compression fractures with <40% loss of height and no posterior tenderness can be managed in a brace. Kyphoplasty and vertebroplasty, which involve injection of viscous cement into the fracture bed, are emerging as therapeutic options. Their role is still being defined in the acute setting.

Figure 18-9. T9 compression fracture as seen on lateral radiograph (A) and axial computed tomography scan(B).

• Imaging (CT, MRI) is indicated for any compression fracture associated with neurologic injury, >30% loss of height of vertebral body, and any patient with posterior tenderness or widening of the pedicles on an AP view. These patients should be evaluated by a spine surgeon.

B.

Burst fractures involve the anterior two columns and are generally considered unstable. X-ray findings are positive when the lateral view shows loss of vertebral height, widening of the spinous processes, or interruption of the posterior vertebral body line. The AP view shows widening of the pedicles, widening between the spinous processes, and loss of vertebral height. Many of these patients have neurologic injury. All of these fractures should have detailed imaging studies and the patients should receive spine service consultation. Although surgical fusion remains the standard of care, neurologically intact patients without evidence of damage to the posterior osteoligamentous complex may be managed in an extension brace for 3 months. Patients receive close radiographic follow-up with concern for progressive kyphosis. Patients with a progressive deficit require emergent operative intervention. Surgery may be deferred in those with a stable deficit for the theoretical benefit of allowing progression and resolution of cord edema and inflammation, which may reduce the risk of iatrogenic injury.

C. Flexion or distraction (seat belt or Chance) fractures

This axially oriented fracture is caused by a flexion injury around an anterior fulcrum (lap belt without shoulder harness). The fracture can split the pedicles in half, tear open the disc space, or spare bone elements and be ligamentous in nature. The excessive flexion motion places the spine in kyphosis. This injury is associated with a 30% to 45% incidence of abdominal injury and 13% risk of paralysis. Some of the pure bony injuries can be managed nonoperatively by placing the patients in an extension brace to bring the fractured bony elements into apposition, but ligamentous injuries require surgery. These injuries require detailed imaging studies.

D.

Fracture-dislocations are highly unstable and require imaging studies on all patients. Most occur at the thoracolumbar junction. The more cephalad the injury, the more likely paraplegia will result (90% above T10 and 60% below T10). The AP and lateral views will show translation of the spine as well as fractures in the facets, dislocations, or comminution fraction. These injuries require detailed radiographic studies, followed by surgical stabilization.

E.

Sacral fractures are difficult to see on x-ray film and will require CT for delineation. Fractures lateral to the sacral foramen have a 6% incidence of neurologic injury (L5 root) and fractures through the foramen have a 28% incidence. Fractures medial to the foramen through the canal have an associated neurologic injury in 57%, most involving bowel and bladder function. Displaced fractures can require surgery.

IX. Gunshot Wounds to the Spine

A.

Penetrating injuries to the spine should be treated as elsewhere in the body. The standard surgical principles of debridement and closure can be applied. The caveat is that patients with cerebrospinal fluid (CSF) leaks are at risk of meningitis and paravertebral abscess formation, unless CSF egress is controlled. Steroid therapy is contraindicated in this population due to the risk of infection.

B.

In general, large penetrating wounds require exploration and debridement. Wound cultures are taken and all potentially contaminating material (e.g., clothing fragments or shotgun wadding) is removed. Passage through the esophagus, pharynx, or colon before traversing the spine has the potential to cause spinal sepsis. Radical debridement of the spine is no longer advocated in this situation. Minimal debridement of bullet tract and 1 to 2 weeks of broad-spectrum antibiotics is

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sufficient to decrease the chance of spinal infection to about 10% of cases when the bullet traverses the colon, esophagus, or pharynx.

C.

Removing bullet fragments may necessarily be delayed if an abnormal lead level develops. Removal of a bullet from the spinal canal is recommended with a worsening neurologic picture or evidence of neurologic compression on radiographic studies. These procedures can be facilitated if performed in a delayed fashion to allow easier dural repair. CSF diversion (e.g., lumbar, cervical, or ventricular drainage) may be required for persistent leakage. Neurologic deterioration mandates a more urgent approach to debridement.

D.

Few civilian spinal injuries caused by the bullet striking the spinal column are unstable enough to require surgical stabilization. The three-column theory can be used to dictate treatment. If two of three columns are involved, a rigid orthosis is necessary. Flexion or extension films may be necessary to determine stability.

Axioms

• The most important factors when treating injuries to the spine are attention to the mechanism of injury, understanding the level of neurologic function at the time of injury compared to later presentation, maintaining a continual awareness of other injuries to the spine, confounding injuries, and patient variables.
• The most commonly missed fractures occur at the C1 to C2 and C7 levels.
• The general assumption is that all patients have an unstable spine until proven otherwise.
• Patients with continued complaints of spine-related pain must be thoroughly evaluated and this evaluation must be repeated if the symptoms persist.
• Patients with ankylosing spondylitis have a significant risk of missed or iatrogenic injury and should be managed closely by a spine specialist.
• Should any doubt about the injury persist, evaluation by a spine surgeon is necessary.