19 SPINAL CORD INJURIES
J. Paul Elliott M.D., Sanjay Misra M.D.

1. What is the difference between a spinal injury and a spinal cord injury?

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Spinal injuries include damage to the bone, disc, or ligaments. These injuries sometimes result in spinal instability. They also may be associated with spinal cord injury, which is damage to the neural tissue, often with clinical deficit. It is crucial to determine whether there is (1) a spinal injury, (2) a spinal cord injury, and (3) spinal instability.

2. Describe the evaluation of a patient with a suspected spine injury.

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First, be sure that the patient is adequately immobilized and everyone knows to maintain spinal precautions. Second, inspect and palpate the spine for external trauma and step-off. Finally, do a complete neurologic examination including all four extremities. Assess strength, sensation (light touch/proprioception and pain/temperature), muscle tone, reflexes, and rectal tone. Carefully document your results.

3. How do you minimze the risk of additional spine injury in hospital?

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Trauma patients should be protected with a rigid cervical collar. The thoracic and lumbar spine are protected using initial spine board immobilization. The patient should be log-rolled during initial evaluation, then removed from the board and transferred to an appropriate hospital bed to prevent decubitus ulcers. Spine precautions should be maintained until the spine is “cleared,” meaning there is no spinal instability or the instability has been treated.

4. How is the level of the spinal cord injury defined?

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The level does not refer to the level of the injury to the spinal column (vertebrae, discs, and ligaments) but to the most caudal level in the cord with intact function. If a patient has normal function of the deltoids (C5) and little or no function of the biceps (C6) or below, the patient has a C5 motor level injury. Right and left sides should be documented separately.

5. Which injuries commonly are associated with cervical spine injury?

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Head injury. Forces associated with significant head and brain injury may be transmitted throug the cervical spine. Of patients with spinal cord injuries, 50% have associated head injuries. Approximately 15% of patients with one spine injury have a second injury elsewhere in the spine.

6. How can the spinal cord be evaluated in patients with associated head injury?

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All patients should have a rectal examination to evaluate tone. A patulous anus is a good indication of spinal cord or cauda equina injury. Flaccid motor tone and absent reflexes should raise suspicion of spinal cord injury. These findings are extremely unusual with isolated brain injury. Priapism is common with spinal cord injury but not caused by head injury. Radiographic imaging should be used liberally when a spinal cord injury is suspected.

7. Which other significant injury may present as a high thoracic cord lesion?

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Thoracic aortic dissection may present as a T4 region cord injury. T4 is a watershed zone in the cord between the vertebral arterial distribution and the aortic radicular arteries.

8. What is spinal shock?

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Absence of all spinal cord function below the level of the lesion results in flaccid motor tone and areflexia. Neurogenic shock refers to the hypotension that may result from cervical or upper thoracic complete spinal cord lesions. The hypotension is due to the lack of sympathetic vasomotor innervation below the lesion and is characterized by bradycardia from unbalanced vagal input to the heart. Fluid resuscitation and pressors with both α and β stimulation work best. Strictly a stimulation may result in profound bradycardia or asystole. Usually the spinal shock resolves, and vasomotor tone returns over the first few days. Occasionally, apparent complete injuries significantly improve or resolve because of resolution of diffuse cord dysfunction-the cause is not clear.

9. Describe an adequate radiologic evaluation.

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Minimal cervical spine evaluation includes cross-table lateral, anteroposterior, and open-mouth odontoid views. The relationship between C7 and the top of T1 must be visualized. Mild traction on the shoulders with the lateral film or swimmer’s views help in patients with large shoulders. If this area cannot be seen on plain films, a lateral tomogram or computed tomography (CT) scan may be needed. Oblique views are helpful in viewing the pedicles and facet joints. For the thoracic and lumbosacral spine, anteroposterior and lateral views are obtained. Patients with evidence of possible fractures should have CT scans to define the injury in greater detail. Spiral CT scans may be used for rapid screening.

10. Describe the proper way to read a lateral cervical spine film.

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Make a habit of doing a thorough systematic review in the same way with every film. First look at the prevertebral soft tissue space, which may be the only radiographic abnormality in 40% of C1 and C2 fractures. The space anterior to C3 should not exceed one third of the body of C3. At the C6 level, the entire body of C6 generally fits into the prevertebral soft tissue space. Check the alignment of the anterior, then posterior edges of the vertebral bodies. Be sure that the intervertebral disc spaces are of relatively equal height. Assess each facet joint. Check the spinous processes for alignment and abnormal splaying. Finally, evaluate each vertebra for fracture.

11. What about the anteroposterior (AP) film?

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Carefully inspect the alignment of the midline spinous processes. Abrupt angulations suggest unilateral facet dislocation. More subtle changes may indicate facet instability or fracture. Body fractures may be more obvious in the AP view.

12. Can a patient have a spinal cord injury and normal plain radiographs?

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Yes, with purely ligamentous injuries between vertebrae. Spinal cord injury without radiographic abnormality (SCIWORA) is common in children; 30% of children with spinal cord injuries have no radiographic abnormality. SCIWORA is less common in adults (about 5% of spinal cord injuries). In patients with preexisting cervical stenosis, either congenital or degenerative, hyperextension or flexion may result in cord injury without spinal column disruption.

13. Is magnetic resonance imaging (MRI) useful in the evaluation of acute spine trauma?

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Yes. If plain radiographs and CT scans do not explain adequately the extent of injury noted on the neurologic examinations, MRI should be used to evaluate the spine for herniated discs, ligamentous injuries, and evidence of spinal cord injury.

14. Fractures of C1 and C2 are visualized best with which view?

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The odontoid view. Look for overhang of the lateral mass of C1 off the lateral edges of C2. This occurs in Jefferson’s fractures (burst fractures of the C1 ring). Sum total overhang of both C1 lateral masses on C2 of ≥ 7 mm is associated with disruption of the transverse ligament and instability. If you see a C1 fracture, look carefully for a C2 fracture. The three types of odontoid fractures are:

* Type I occurs in the dens.
* Type II occurs across the base of the dens where it joins the body of C2.
* Type III extends into the body of C2.

Type II dens fracture requires a halo or operative screw fixation. Get a CT scan to investigate fully any fracture suspected on plain films.

15. What is hangman’s fracture?

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Bilateral fractures through the pedicles or pars interarticularis of C2 that are caused by a severe hyperextension injury, usually secondary to high-speed motor vehicle accidents. Think about the mechanism of injury: the C2-C3 disc space may be disrupted anteriorly. In judicial hangings, the fatal injury is the spinal cord stretch caused by the drop in combination with the C2 fracture. Most patients with hangman’s fracture present neurologically intact. They are often treated with a halo.

16. Define deficits in complete transverse myelopathy, anterior cord syndrome, central cord syndrome, and Brown-Séquard syndrome.

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Complete transverse myelopathy may result from transection, stretch, or contusion of the cord. All function below the level of the lesion-motor, sensory, and reflexive-is lost. Complete transverse myelopathy may be accompanied by spinal shock or neurogenic shock. Approximately 50% of spinal cord injuries are complete.
Anterior cord syndrome results from injury of the anterior two thirds of the spinal cord (the distribution of the anterior spinal artery), which carries motor, pain, and temperature tracts. Light touch and proprioception are intact because the posterior columns are preserved.
Central cord syndrome results from injury to the central area of the spinal cord. Often it is found in patients with preexisting cervical stenosis resulting from spondylotic changes. Characteristically, deficits are more severe in the upper extremities than in the lower extremities. Motor function usually is affected more than sensory function.
Brown-Séquard syndrome characteristically is seen in penetrating injuries, but also may be seen in blunt injury, especially with unilateral, traumatically herniated discs. The syndrome results from injury to half of the spinal cord. Clinically, motor, position, and vibration sense are affected on the side ipsilateral to the injury; these tracts cross in the brainstem. Pain and temperature sensation are abolished contralateral to the lesion; these tracts cross in the cord at or near the level of innervation.

KEY POINTS: DIAGNOSTIC PEARLS FOR TRAUMATIC SPINAL CORD INJURY

1. Complete traverse myelopathy: complete distal motor, sensory, and reflexive deficit.
2. Anterior cord syndrome: loss of motor, pain, and temperature sensation with preservation of light touch and proprioception since the posterior columns are intact.
3. Central cord syndrome: deficits more severe in upper than lower extremities and motor function affected more than sensory function.
4. Brown-Séquard syndrome: loss of ipsilateral motor, position, and vibratory senses and contralateral pain and temperature sense.

17. What is the role of methylprednisolone in the treatment of acute cord injury?

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The results of the Second National Acute Spinal Cord Injury Study (NASCIS II) suggest that high-dose methylprednisolone results in a statistically significant improvement in outcome. The dose is a 30-mg/kg load, followed by 5.4 mg/kg/h for 23 hours. The NASCIS III trial reported that patients dosed 3-8 hours after injury had improved outcomes when treated for 48 hours with the methylprednisolone rather than 24 hours. In patients dosed within 3 hours of injury, no further gains were documented by treating beyond 24 hours. Penetrating trauma was not evaluated in the study. Reevaluation of available data has put the value of these steroids in doubt.

18. Do patients with spinal cord injuries ever undergo acute surgery?

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Yes. Patients with deterioration in the neurologic examination may undergo urgent spinal cord decompression. Deterioration may be due to herniated disc material, epidural hemorrhage, or cord swelling in a narrowed canal, causing cord compression and worsening symptoms. Patients also undergo surgery for stabilization of an unstable spine to allow early mobilization and rehabilitation.

19. How is the bony injury treated?

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1. Prevention of further injury using spinal precautions
2. Obtaining normal alignment using body position, traction, and bracing
3. Open reduction, decompression, and fusion as necessary

20. What is the outcome in patients with spinal cord injury?

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With complete lesions (no motor or sensory function below the lesion), the chances of recovery are poor; 2% of patients recover ambulation. The prognosis is markedly better for patients with incomplete lesions-75% experience significant recovery. Appropriate treatment of bony injuries helps to prevent pain and late neurologic deterioration.

References
WEB SITE
http://www.acssurgery.com/abstracts/acs/acs0502.htm

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