Acute Spinal Cord Injury

Scott Meyer, Jennifer A. Frontera, Arthur Jenkins III, and Tanvir Choudhri

Spinal cord injuries (SCIs) inflict a significant burden on patients, families, and society as a whole. The spinal cord consists of 31 segments and terminates near L1 (T10-L3) in adults. Most injuries involve not only the cord, but exiting nerves as well. SCI is most common in the young (average age 29 years) and in men (78%).1 The most common causes of SCI are motor vehicle accidents (MVAs; 47%), falls (23%), violence (14%), sporting accidents (9%), and other causes (7%).¹ Alcohol plays a role in up to 25% of SCI and underlying spinal disease such as cervical spondylosis, atlantoaxial instability, osteoporosis, and spinal arthropathies can make patients more prone to SCI. Roughly half of all SCIs involve the cervical cord.

SCI can be divided into two separate mechanisms of action: primary and secondary SCI. Primary SCI occurs as a result of pathologic flexion, rotation, extension, compression, contusion, or shearing of the spinal cord. This can be caused by a fracture-dislocation, tearing of ligaments, or disruption and/or herniation of the intervertebral disks. Kinetic injury transmitted from bullet wounds or blasts can cause cord injury even when no foreign body has entered the spinal column. The primary SCI is irreversible, and prevention of the initial injury is the primary modifiable feature. Secondary SCI is a complex chain of events linked to ischemia, hypoxia, edema, excitotoxicity, and inflammation with changes on the cellular level. Aims of intervention and management are to limit the effects of secondary injury processes as well as prevent associated medical morbidities.

Case Example

A 19-year-old man has just arrived by ambulance after a fall from his motorcycle and is complaining of neck pain, weakness, and numbness in all four extremities.

Questions

Are there any external signs of injury?
Is there additional head or body trauma?
What is the current level of consciousness?
Is he able to move all of his extremities, and is there any change since the event?
Is he hemodynamically stable?

Urgent Orders

Address airway, breathing, circulation (ABCs). Up to 33% of patients with cervical spine injury will require intubation. Rapid-sequence intubation with in-line spinal immobilization is the preferred method when an airway is urgently needed. For elective intubations, use of a flexible fiberoptic laryngoscope or video-assisted intubating device may be appropriate.
Appropriate spinal immobilization includes placement of a rigid cervical collar, barriers to lateral head movements, use of a backboard, and log-roll movements.
Upon confirmation of neurologic deficit with suspected SCI, consider methylprednisolone for 24 to 48 hours (see below).
Place Foley catheter to avoid harm due to bladder distention.
Address other potential trauma. Order focused abdominal sonogram for trauma (FAST exam evaluates pericardium, right and left upper abdomen, and pelvic region for blood) if indicated; computed tomography (CT) of chest, abdomen, and pelvis when the patient is stabilized.
Order complete blood count (CBC), chemistry panel, coagulation studies, type and cross, toxicology screen, arterial blood gas, and pregnancy test (if applicable).
Maintain PaO2 >60 mm Hg and systolic blood pressure (SBP) ≥90 mm Hg.
Perform noncontrast head CT, spine CT, and/or cervical x-rays (see below).

History and Examination

History

Events surrounding the accident: Use of a seatbelt or helmet, type of vehicle (motorcycle or automobile), position of the patient in the vehicle, direction from which the vehicle was hit, speed of collision, windshield or steering wheel damage (may indicate concomitant injury, aortic rupture, or other systemic injury)
Assess for use of ethyl alcohol (EtOH) or illicit drugs, as these may confound the exam.
Passive rewarming of hypothermic trauma patients is crucial prior to assessing the neurologic examination.

Physical Examination

Close attention should be paid to the hemodynamic status of the patient. Because SCI may be associated with other traumatic injuries, it is important to monitor blood pressure and heart rate. In addition, neurogenic shock may result in bradycardia and hypotension. Adequate oxygen saturation and blood pressure are important to monitor to help prevent ischemic insult to the spinal cord.
The body should be inspected for signs of external trauma. Palpation of the spinal column to assess for tenderness or step-off should be undertaken. The seventh (and occasionally even the sixth) spinous process is prominent and should not be confused with subluxation.
Make sure that full spinal precautions are maintained throughout the examination.

Neurologic Examination

A full neurologic examination, including assessment of mental status, cranial nerves, motor skills, and reflexes, as well as a sensory and cerebellar exam, should be performed on all patients.

Abnormal mental status may be a sign of the need for airway protection, potential intracranial injury, or intoxication and may limit the motor and sensory portions of the initial neurologic examination.
All muscle groups should be examined and recorded using a 5-point scale.
A complete sensory examination should be performed, including assessment of a sensory level (using pinprick and vibration) and crossed sensory signs (indicative of a Brown-Séquard hemicord lesion).
Reflexes should be assessed, including deep tendon reflexes, sphincter tone, and the bulbocavernosus reflex. Reflexes may be depressed acutely after injury and become hyperacute over days to weeks.
Assessment of sacral function (perineal sensation, bulbocavernous reflex S3-S4, anal wink S5, priapism, rectal tone, and urine retention or postvoid residual) is important for prognostication.

See Table 8.1 for the American Spinal Injury Association (ASIA) Scaleand Table 8.2 for examination findings in different types of SCI.

**Table 8.1** American Spinal Injury Association Scale
Category	Description
A	Complete: No motor or sensory function is preserved below the neurologic level through sacral segments S4-S5.
B	Incomplete: Sensory but not motor function is preserved below the neurologic level and includes S4-S5.
C	Incomplete: Motor function is preserved below the neurologic level, and more than half of key muscles below the neurologic level have a muscle grade <3.
D	Incomplete: Motor function is preserved below the neurologic level, and at least half of key muscles below the neurologic level have a muscle grade ≥3.
E	Motor and sensory functions are normal.

Data from: Clinical assessment after acute cervical spinal cord injury. Neurosurgery 2002; 50(3, Suppl)S21-S29.

Differential Diagnosis

Acute Presentation

Spinal cord trauma

Fracture of bony elements with cord or nerve injury

Jefferson fracture (Fig. 8.1): Typically a four-part fracture of the atlas (C1), with bilateral fractures to the anterior and posterior arches, usually from axial load compression (such as from a diving injury)

Hangman’s fracture (traumatic spondylolisthesis) (Fig. 8.2): Bilateral pars fracture of axis (C2) vertebral body with various degrees of anterior subluxation and disruption of the C2/3 disk space, usually due to extension trauma from an MVA or hanging

Ligamentous injury (injury causing subluxation may only be seen on dynamic studies such as flexion-extension plain films or magnetic resonance imaging [MRI])

Herniation of intervertebral disk

Penetrating injury (bullet, knife wound, etc.)

Kinetic injury (blast or nearby bullet wound)

Spinal cord injury without radiographic abnormality (SCIWORA): More common in children; may be due to longitudinal distraction or transient ligamentous deformation with spontaneous reduction
Vascular. The blood supply to the cord consists of one anterior and two posterior arteries.
- Carotid/vertebral dissection can occur in the setting of trauma or bony fracture. Consider arterial imaging with CT angiogram, magnetic resonance angiography (MRA), or digital subtraction angiography.
- Spinal cord infarction can be due to vessel disruption, emboli, or hypoperfusion. T4-T8 represents the watershed territory between the anterior spinal artery and the artery of Adamkiewicz originating at T9. At any particular level, the central part of the cord is the watershed area. Cervical hyperextension injuries can cause ischemia, resulting in central cord syndrome. Minor vascular supply comes from branches of the vertebral artery and thyrocervical trunk as well, so injury to these structures may lead to ischemia.
- Vascular malformations
- Epidural hematoma