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Trauma to the Spine and Spinal Cord
Clinical Vignette
After a day of skiing, six teenagers packed into a small hatchback on their way home. Conditions were icy, and the driver lost control of the vehicle near the base of the mountain, rear-ending another vehicle at approximately 30 miles/h. One of the passengers, an 18-year-old man, struck his head on the seat in front of him. When Emergency Medical Services arrived on scene, the patient's primary complaint was neck pain. He was subsequently placed in a hard cervical collar and transported to the nearest trauma center.
On arrival, computed tomography (CT) of the patient's cervical spine demonstrated a fracture of the axis through the base of the odontoid process. The patient was neurologically intact, with no complaints apart from continued neck pain. After extensive discussions regarding possible options for management, the patient underwent odontoid screw fixation. The operation was uncomplicated, and the patient was released after a 2-day stay in the hospital.
At the 1-month follow-up, the patient was recovering well. His neck pain had completely resolved, and he had no new neurologic deficits. Imaging showed good positioning of the odontoid screw and reapproximation of the fractured odontoid with the body of the axis. The patient had no limitations in his cervical range of motion and had returned to school 2 weeks earlier to continue his senior year.
Comment: This patient represents a common spine fracture in an unusual demographic; odontoid fractures are most common in the elderly population. Although the majority of patients who present to the hospital with this fracture have no evidence of neurologic deficit, odontoid fractures are unstable and require stabilization—either externally with a brace or internally through surgical fixation. The morphology of the fracture and individual patient characteristics are the key factors to be weighed in making the treatment plan.
In this case, the patient's fracture anatomy made the success of external fixation unlikely; the majority of fractures through the base of the dens (so-called type II fractures) fail to resolve with bracing alone. On the basis of the patient's imaging findings, the decision was made to proceed with placement of an odontoid screw, using a ventral approach that places a single screw through the axis and the fractured fragment. Such an approach allows for the preservation of rotational motion at the atlantoaxial junction, an especially important consideration in a young, active patient.
This case illustrates many of the complexities of spine trauma management:
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the need for appropriate evaluation and stabilization of patients from the arrival of emergency medical services to the patient's initial evaluation in the hospital
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the importance of accurate imaging and appropriate diagnosis
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numerous subtle but vital patient characteristics that determine the final course of management.
Traumatic spine fractures and associated traumatic spinal cord injury (TSCI) are among the most devastating injuries that medical professionals encounter. Apart from the acute challenges represented by such patients (who frequently present with multiple life-threatening injuries and are in need of rapid and definitive treatment), TSCI invariably results in social, economic, and medical challenges, which, in many ways, are unparalleled. Early documented recognition of the seriousness of spinal cord injury is recorded on the Edwin Smith Surgical Papyrus, Egypt (17th century bc ). Modern causes of spinal cord injury are diverse, ranging from motor vehicle accidents ( Fig. 20.1 ) to sports-related injuries to trauma sustained in armed conflicts. Regardless of etiology, these patients require comprehensive multidisciplinary care to identify and address the long-term medical, social, and psychological issues following spinal cord injury.
Cervical Spine Injury: Compression.
Despite the multiple challenges faced by patients with TSCI, most of them are able to live active, productive lives that are substantially longer than could be achieved after TSCI 50 years ago. To watch paraplegic individuals in wheelchairs come to the finish line of the Boston Marathon or those competing in the Paralympic Games speaks to these triumphs. The future of TSCI treatment also holds great promise, with advances in stem cell technology and robotics progressing at a staggering rate.
Major trauma centers evaluate 2 to 3 TSCI individuals out of every 100 patients brought to their emergency departments. The very high mortality (50%) associated with TSCI occurs mainly at the initial accident or injury scene. In addition to TSCI, many of these patients have injuries to other body systems, including traumatic brain injuries, orthopedic injuries, cardiopulmonary injuries, and visceral injuries. Of the patients who make it to the hospital, mortality is approximately 16%.
Although young men sustain 85% of TSCIs, the increasing age of the overall population in many Western countries is shifting the demographics of TSCI. In the older population, individuals with significant cervical spinal spondylosis and/or stenosis are much more likely to develop TSCIs, such as a central cord injury ( Fig. 20.2 ), from relatively simple ground-level falls.
Cervical Spine Injury: Hyperextension.
In the United States alone, the annual cost of caring for TSCI patients is estimated to be over $9.7 billion. Furthermore, the patient with a spinal cord injury must adjust to limited mobility, psychiatric issues, urologic problems, pulmonary difficulty, skin breakdown, sexual dysfunction, and frequently the inability to perform his or her job. The higher the neurologic injury within the spinal cord, the more difficult the patient's adjustment to the injury and the higher the associated costs. The patient in the opening vignette of this chapter was fortunate to not experience any long-term sequelae from his injury, as a large proportion of patients presenting with spine trauma do have persistent neurologic dysfunction. Although we may have interventions in the near future that can ameliorate the effects of TSCI, prevention of such injuries remains the best way to reduce the burden of TSCI. Think First, a program sponsored by the American Association of Neurological Surgeons that reaches millions of students across the United States and in a number of foreign countries, seeks to educate school-aged children about TSCI prevention.
Pathophysiology
Traumatic injuries of various types can result in TSCI. Among the most common, particularly among adolescents, are those related to diving accidents or vehicular trauma resulting in compression injury to the vertebrae and the spinal cord (see Fig. 20.1 ). TSCI in the elderly population is often the result of ground-level falls in the home (see Fig. 20.2 ); similarly, individuals with ambulatory instability are at significantly increased risk of spinal cord trauma due to falls ( Fig. 20.3 ).
Vertebral fractures can result in damage to the spinal cord ( Fig. 20.4 ), which may range in severity from a mild contusion to a total severing of the cord. In addition to the initial trauma during the event, there is often significant delayed intramedullary microvascular thrombosis within the spinal cord. This frequently leads to progressive secondary injury due to cord ischemia, microhemorrhages, and necrosis. Toxic excitatory amines produced by the trauma worsen the secondary injury.
Initial Management
As with any serious traumatic event, patients with TSCI often present with multiple concurrent injuries that may lead to issues such as hypotension, hypoxia, and infection. Some of these may require surgical intervention or stabilization before any TSCI may be addressed, and these patients frequently benefit from advanced multidisciplinary care. As with any trauma, the ABCs of Advanced Trauma Life Support (i.e., airway, breathing, and circulation) demand immediate medical attention. Because any degree of hypotension and hypoxia will further exacerbate the intrinsic spinal cord injury, it is absolutely essential that everything be done to minimize any subsequent injury to the contused spinal cord secondary to inadequate blood supply and/or oxygen ( Fig. 20.5 ). Once the patient is stabilized, a detailed neurologic examination is undertaken. Any motor deficits, sensory changes, and deep tendon reflex abnormalities must be documented meticulously. Several classification schemes assist in describing findings. The American Spinal Injury Association (ASIA) scale is commonly used and stratifies injuries from A (no motor or sensory function) through E (normal sensory and motor function) ( Table 20.1 ). Positive findings also guide further evaluation with diagnostic imaging.
TABLE 20.1
American Spinal Injury Association Classification
From American Spinal Injury Association. International Standards for Neurological Classifications of Spinal Cord Injury. Revised edition. Chicago, IL: American Spinal Injury Association; 2000:1–23.
| ASIA Classification | Description |
|---|---|
| A (Complete) | No motor or sensory function below level of injury preserved including the sacral segments S4 or S5 |
| B (Sensory Incomplete) | Sensory but no motor function is preserved below the level of injury, including the sacral segments S4 and S5 |
| C (Motor Incomplete) | Motor function is preserved below the level of injury, with more than half of muscle groups having a muscle grade of <3/5 |
| D (Motor Incomplete) | Motor function is preserved below the level of injury, with more than half of muscle groups having a muscle grade of ≥3/5 |
| E (Normal) | No motor or sensory deficits |
ASIA, American Spinal Injury Association.
Diagnostic Approach
Cervical Spine
In any patient in whom cervical spinal injury is suspected, the neck should be immobilized in a rigid collar as soon as possible. Most trauma patients require spinal CT examination, and injuries may be detected even in patients who complain of neck pain and/or tenderness without obvious neurologic deficits. The advantages of CT scanning are the rapidity with which imaging can be obtained and its high sensitivity and specificity for bony spinal injury (see Figs. 20.1 and 20.2 ). CT also offers the ability to digitally reconstruct acquired images in sagittal, coronal, axial, and oblique views to better detect abnormalities. In settings lacking CT scan capabilities, plain x-ray remains a valuable screening resource, especially when making decisions about the escalation of care in patients with suspected spinal injury. This three-view cervical spine study must include lateral, anteroposterior, and open-mouth views of the odontoid. It is essential to visualize the entire cervical spine from the occiput through T1. Whenever this traditional imaging is inadequate or provides questionable findings, thin-cut CT scanning with reconstruction through the questionable areas must be obtained.
Whenever there is any neurologic deficit, magnetic resonance imaging (MRI) (see Fig. 20.2 ) is performed before removing the collar or instituting therapy. An MRI will provide evidence of any spinal cord injury, nerve root compression, disc herniation, or ligamentous/soft tissue injury. A normal examination provides evidence that it may be safe to remove the collar support and allow early mobilization. Formal MRI may not be necessary if the trauma patient is alert, has no neck pain or tenderness, has full painless range of motion of the neck, demonstrates a normal neurologic examination, and shows no evidence of active intoxication.
In the case of the neurologically intact patient with definite posttraumatic neck pain whose cervical radiographic and/or CT findings are normal, it is still essential to evaluate for the possibility of a subtle but unstable fracture dislocation with potential for severe cord injury. Dynamic, lateral flexion/extension radiographs or fluoroscopy will indicate dislocation. The neck excursions required for these procedures can be performed only when the patient is lucid and cooperative. If the patient is uncooperative or obtunded, he or she must be kept in the rigid collar until flexion-extension films can be performed passively by a trained provider.
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