Prehospital Care spinal cord injuries

Prehospital Care

A.

Treatment in the field of patients with spinal column and spinal cord injuries follows the basic prehospital protocols (Chapter 6). Treatment is directed to establishment of an adequate airway, ventilation of the lungs, and maintenance of circulatory support to prevent secondary neurologic injuries.

B.

Intubation is best accomplished by using manual inline immobilization, avoiding flexion of the neck. Fiberoptic intubation may also reduce spine manipulation. The patient's neurologic status as well as pulmonary function should be assessed and recorded, especially patients with high quadriplegia.

Figure 18-1. Drawing showing the three columns of support in the spine.

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C.

Hypovolemic and neurogenic shock can occur in the setting of SCI. The cause of hypotension must be determined and treated immediately. Hypotension should be regarded as a sign of abdominal bleeding, aortic or cardiac injury, external blood loss, or occult injury before considering neurogenic shock. Regardless of the cause, shock should be aggressively treated to prevent further ischemic injury to the spinal cord. Treatment consists of fluid administration and vasopressors to maintain the mean systemic blood pressure at approximately 90 mmHg. The patient is reevaluated continuously in the emergency department. Resuscitative measures are continued and modified as needed.

D.

An estimated 3% to 25% of spinal cord injuries occur iatrogenically after the initial trauma, either in transport or during early resuscitation. After medical stabilization on the scene, the cervical spine should be immobilized in a rigid collar in any patient who is unconscious or suspected of having a cervical injury. A scoop stretcher or similar backboard with supportive blocks and straps should be used rather than logrolling to prevent uncontrolled motion. The patient should remain on a backboard until evaluated in the emergency department. Transport to a definitive treatment center should be the goal, as delays can incur worse outcomes, longer hospitalization, and higher costs.

IV. Neurologic Evaluation

A.

A standard neurologic examination is performed on each patient. This includes evaluation of mental status, cranial nerves, motor testing, sensory testing, and reflex assessment. Further specialized testing can be deferred.

B.

The Glasgow Coma Scale (GCS) score is determined and recorded. The mental status is established as to person, place, and dates, surrounding the events. Cranial nerve evaluation is done with special attention directed to pupillary size and symmetry. Acute changes in the pupillary diameter can indicate a brain herniation syndrome and may require emergent surgery, hyperventilation, or diuresis.

C.

Motor evaluation is performed for the GCS and SCI evaluation. The patient is asked to move all extremities individually and strength is assessed according to the American Spinal Injury Association/International Medical Society of Paraplegia (ASIA/IMSOP) protocol. Normal strength is graded 5/5, with mild weakness graded as 4/5. The ability to fully overcome gravity through a full range of motion is graded 3/5. Movement throughout a range of motion but unable to overcome gravity is graded 2/5. Flicker motion of muscles is 1/5 and no movement is 0/5. Patients with C5 levels of spinal cord function will be able to flex only their arms and should not be confused with pathological flexor posturing.

D.

Sensory testing is performed with regard to light touch and pain perception (Fig. 18-2). Useful examination tools include a cotton swab broken in half or safety pins. Pay close attention to the level of sensation and asymmetry.

E.

Reflex testing is performed at the biceps (C5), triceps (C7), brachioradialis, knee (L4), and ankle areas (S1). Special reflex testing including jaw jerk, deltoid (C5), pectoral, superficial abdominal (T9-T12), bulbo- or cliterocavernositis (S3-S4), anal wink (S5), and Babinski. The extremity reflexes are graded on a scale of 0 to 4, where 0 = absent reflex activity, 1 = decreased reflex activity, 2 = normal reflex activity, 3 = increased reflex activity, and 4 = grossly exaggerated reflex activity with sustained clonus. An exaggerated jaw jerk indicates injury at or above the pons. Deltoid and pectoral reflexes are usually associated with significant hyperreflexia. Bulbo- or cliterocavernosis reflexes may be retained in complete injury, but lost during spinal shock. Their reappearance may indicate that a period of spinal shock has ended. Babinski responses are recorded as present or absent. The presence of UMN findings (hyperreflexia, loss of superficial abdominal reflexes, Babinski responses) indicates spinal cord or conus medullaris injury. Decreased reflexes imply LMN (cauda equina and nerve root) injury. Weakness, sensory loss, and bladder, bowel, and sexual dysfunction can be seen with either UMN or LMN injuries. Of note, acute UMN injuries often present with reflex stunning or are-flexia, which may last for 24 to 48 hours.

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Figure 18-2. Anterior (A) and posterior (B) cervical, thoracic, lumbar, and sacral dermatomes. (From McDonald JV, Welch WC. Patient history and neurologic examination. In: Welch WC, Jacobs GB, Jackson RP, eds. Operative Spinal Surgery. Stamford, Conn: Appleton & Lange; 1999;3:15, with permission.)

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F.

The most sensitive predictor of prognosis is the severity of neurologic injury as characterized by level and completeness of deficit. The neurologic sensory levels are determined and recorded based on the lowest segment with normal sensory and motor function bilaterally. Complete injury is seen in the patient without sensory or motor function below the level of neurologic injury, including loss of perianal sensation and sphincteric function. The patient with incomplete injury has partial preservation of sensory or motor function below the level of neurologic injury, with preservation of perianal sensation and motor function. This is often referred to as sacral sparing, and does not include an intact bulbo/clitoro cavernosus reflex which can be present in complete injuries.

G.

In the acute setting, the use of specific terms denoting neurologic level is preferable to more general terms (e.g., paraparesis, quadriplegia). The ASIA impairment scale, consisting of a five-point grading scale, is as follows:

• Complete loss of sensory and motor function (including the sacral area) below the neurologic level.
• Incomplete injury, whereby sensory function is preserved below the level of neurologic injury including the sacral area.
• Incomplete injury with motor function preserved below the neurologic level and most preserved groups exhibiting strength of ≤3.
• Incomplete injury with motor function preserved below the neurologic level and most preserved groups exhibiting ≥3 strength.
• Normal sensory and motor examination. Even patients with ASIA 1 scores can improve neurologically, although few of these patients will achieve functional motor recovery.

H.

Another useful descriptor of spinal cord injuries involves pathologic criteria. These syndromes correlate to anatomic areas of injury.

• Posterior cord injury with loss of position sense (posterior columns) is rarely traumatic. This injury is usually related to vitamin deficiencies and infections (e.g., syphilis). The patients develop a loss of position and vibratory sense.
• Central cord injury is common in patients who experience excessive motion in the sagittal plane (e.g., hyperflexion and hyperextension), particularly those with preexisting cervical stenosis. These injuries represent a centripetal force applied to the spinal cord with resultant central necrosis secondary to vascular compromise. The hallmark features are hand weakness more than leg weakness, bladder dysfunction, and variable degrees of sensory loss below the level of the lesion.
• Anterior cord injury suggests anterior spinal artery occlusion and results in loss of all motor and sensory function other than proprioception.
• Brown-Sequard (cord hemisection) syndrome is identified by loss of ipsilateral motor function, ipsilateral position sense, and contralateral loss of pain and temperature sensation two to three segments below the level of injury.

I.

Conus medullaris and cauda equina syndromes occur at the thoracolumbar levels and result in varying degrees of weakness, sensory loss, bladder, bowel, and sexual dysfunction. Conus injuries affect UMNs, which may precipitate hyper-reflexia. Conus injuries may also cause reflex stunning with the loss of the bulbo-cavernosus reflex. The cauda equina syndrome typically results from a compres-sive lesion below the level of the spinal cord with resultant bowel/bladder dysfunction, saddle paresthesias, and lower extremity weakness. This represents one of the few operative emergencies and should be alleviated as soon as safely possible to attain maximal recovery and prevent further deterioration.

V. Radiographic Evaluation

The diagnosis of spinal cord or spinal column injury is of paramount importance in the acute setting. The diagnosis is reached by obtaining a history of the events, performing a neurologic evaluation of the patient, and obtaining the appropriate radiographic evaluation. The initial studies should cover the area of suspected injury. Patients with persistent complaints of pain along the spine should be assumed to have a spinal column injury until proven otherwise. Patients with a normal x-ray study and severe neck pain should remain in a rigid cervical collar. MRI should be obtained in this setting. Follow-up flexion/extension

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films can be completed about 3 days after injury to rule out instability that was masked by muscle spasm. Keep in mind that 10% to 15% of patients with one spine fracture will have another fracture elsewhere in the spine. The “skeletal level” is used to denote the area of greatest vertebral injury and can be different from the neurologic level(s).

A. Cervical spine

• The cervical spine can be clinically cleared without radiography in patients who present with a GCS of 15, with no evidence of drug or alcohol use, normal neurologic exam, without midline cervical pain, and without distracting or significant injuries. The Canadian C-spine rules provide a well-validated algorithm to avoid unnecessary imaging with a sensitivity of 100%. For the majority of trauma patients who do not meet these guidelines, evaluation starts with plain films. The sensitivity and specificity of plain radiography to detect a fracture remain below 90%. This compares to a reported sensitivity and specificity of 96.0% and 96.5%, respectively, for CT. With a 14.5% probability of paralysis for missed injuries, CT has emerged as the diagnostic modality of choice. However, the negative predictive value of CT combined with plain films exceeds 99%, prompting our institution to always obtain at least a lateral C-spine. Fractures may be missed with CT if they extend horizontally in the axial plane, parallel to the tomographic imaging slice. While cost remains a point of contention, in moderate- to high-risk patients in urban trauma centers, CT can be cost-effective. Of note, the most commonly missed cervical fractures are at the C1 to C2 and C7 to T1 levels, usually the result of inadequate imaging.
• The basic lateral radiographic studies must include the skull base and T1 vertebral body for adequate interpretation. A “swimmer's view” may be required to fully assess C7 to T1. Oblique views may also help assess C7 to T1, although a CT is usually obtained after two attempted failures to obtain adequate plain films. The films are reviewed with careful attention to three lines:
  • Posterior vertebral body line
  • Anterior vertebral body line
  • Spinolaminar line (Fig. 18-3)
• These lines should be uninterrupted and smooth. The appearance of a straight spine (loss of the normal cervical lordosis) indicates extensor muscular spasm and can suggest spinal injury. A rigid cervical collar can also cause loss of lordosis. The vertebral canal is defined as the distance from the spinolaminar line to the posterior vertebral body line. This space available for the cord should be >13 mm at every level. A narrower canal may represent injury or congenital cervical stenosis.
• Soft tissues are then examined. The trachea contains air and provides a line of contrast against the vertebral bodies. Prevertebral swelling indicates a hematoma consistent with spinal column injury. The hematoma can also compromise the patient's airway, leading to respiratory collapse. An easy rule to remember is that the soft-tissue space should be no greater than 6 mm in front of the C2 vertebral body and no greater than 22 mm anterior to C6. Another important distance is the atlantodens interval. This is the space between the anterior aspect of the odontoid (dens) and the ring of C1. This space should not exceed 3.5 mm in the adult and 5 mm in the child. Distances greater than those indicate disruption of the transverse ligament, with resultant instability.
• Vertebral height is examined next, including vertebral body morphology. The vertebral bodies should be similar in appearance, without evidence of compression or fracture. The distance between the posterior spinous processes, or interspinous distance, should be similar at each level.
• Other radiographs obtained of the cervical spine include the open mouth view of C1 to C2. This study shows the base of the odontoid and helps determine whether a type I, II, or III odontoid fracture (discussed below) is present. The lateral masses of C1 are examined with regard to their relationship to C2.

  Figure 18-3. Normal cervical spine lateral radiograph demonstrating spinolaminar line (arrows).

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• Little or no overhang of the lateral masses should be seen. A combined, bilateral overhang ≥6.9 mm indicates a fracture of the ring of C1, with probable disruption of the transverse ligament. The odontoid bone should be symmetrically located between the lateral masses of C2.
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• The anteroposterior (AP) view of the spine is examined for the distance between spinous processes, alignment, and rotation. Facet anatomy is more closely observed with oblique views of the cervical spine. Areas suspected of having fracture can be further assessed with fine-cut CT. MRI is indicated in patients with neurologic deficits or significant fractures that will require reduction. The MRI yields information as to ligamentous integrity, subtle compression fractures, traumatic disc rupture, and SCI. Signal change on long TR images help differentiate acute injury from those that are chronic. Patients with neurologic deficits should be evaluated in consultation with the spine surgery service.
• If a conscious patient has no neck pain to palpation and can voluntarily flex, extend, and rotate without pain, and initial x-rays are normal, the collar may be removed. Should a patient have neck pain and yet have normal preliminary x-rays, further studies should be undertaken. At a minimum, flexion and extension films should be performed to rule out ligamentous instability. These must visualize C7 to T1. A normal three-view films and flex-extension series has a negative predictive values greater than 99%. Further radiographs, including magnetic resonance imaging (MRI) and even bone scan, can be appropriate to rule out possible bone or ligamentous injury. The rigid collar should remain in place until the neck is cleared clinically and radiographically.

B. Thoracolumbar spine

• The thoracolumbar spine is commonly injured at the T12 to L1 levels. This occurs because of the large lever arm created by the inflexible thoracic spine as it joins the lumbar spine. This area of the spine is well examined with lateral and AP views. Three lines are observed along the anterior and posterior aspects of the vertebral bodies, and along the posterior aspect of the spinous processes. The distance between these processes should also remain equal.
• On the AP view, the distance between pedicles is determined as is the distance between the posterior spinous processes. The transverse processes and ribs are evaluated for fractures and the soft tissues are examined for swelling.
• More specialized imaging studies are obtained as necessary. CT is useful for a closer examination of bone anatomy. These studies can be ordered with 1- to 3-mm cuts, and sagittal and coronal reconstruction to better define bony anatomy. MRI provides excellent visualization of the spinal cord and nerve roots and helps define spinal cord and ligamentous injury.
• AP and lateral films are indicated in those patients with symptoms referable to the thoracic area or those who have a mechanism that is consistent with such an injury. This would include patients involved in motorcycle accidents, falls from height, ejection from vehicle, or pedestrian-automobile collisions. Flexion and extension films are not as helpful in this area as compared with the cervical spine. Thoracic spine CT is indicated for those patients with fractures noted on x-ray film or when the anatomy is not well seen on plain films. MRI is indicated for all patients with neurologic findings.

C. Lumbar spine

• The lumbar spine is subjected to injurious forces in falls, motor vehicle crashes, and by other means. Because the spinal cord ends at the L1 to L2 level, true SCI from lumbar fractures is infrequent. Injuries to the conus medullaris and cauda equina can occur if the spinal canal is compromised. Commonly, no neurologic injury is noted with lumbar spine fractures.
• The lumbar spine is evaluated similar to the thoracolumbar spine. AP and lateral spine films are the initial studies.
• CT can be useful to determine the amount of canal compromise in cases of burst fracture. MRI and myelography are also helpful in cases of traumatic nerve root injury, canal compression, and conus medullaris and cauda equina syndromes.

VI. Medical Management of SCI

Once the patient has arrived in the trauma resuscitation area, more sophisticated medical management can begin. The goal is to prevent secondary cord injury, which can be exacerbated by hypotension, shock, hypoxia, hypercoaguability, and hyperthermia. Management protocols include

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definitive treatment of other injuries; maintenance of adequate blood pressure; detailed radiographic studies; high-dose steroids, if appropriate; determination of the need for surgical intervention; and postoperative rehabilitation.

A. Methylprednisolone

A number of studies have suggested that neurologic improvement can occur following the administration of high-dose steroids after blunt injury to the spinal cord. Penetrating trauma to the spine, such as gunshot wounds, are not appropriate candidates, considering the increased risk of infection. The second National Acute Spinal Cord Injury Study (NASCIS 2) showed that methylprednisolone given in a dose of 30 mg/kg intravenously (IV) over 45 minutes within 8 hours after injury in those with incomplete or suspected incomplete SCI improved neurologic outcome. The initial dose is followed by 5.4 mg/kg/h IV given over the next 23 hours by continuous drip. The NASCIS 3 study reported that if patients begin treatment between 3 and 8 hours postinjury, the steroid infusion must be extended to 48 hours to attain the same benefit as 24 hours of steroids given within 3 hours of injury. Significant, functional benefit remains inconclusive and there is no defined standard of care. Currently, the Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injuries (AANS) state that administration of steroids “is recommended as an option in treatment of patients with acute spinal cord injuries that should be undertaken only with the knowledge that the evidence suggesting harmful side effects is more consistent than any suggestion of clinical benefit.” In practice, the protocol is often initiated at referring hospitals prior to transfer. We routinely complete the regimen in these circumstances.

B.

Hemodynamic instability is common in acute SCI. Approximately 70% of patients with high cervical SCI will have severe bradycardia (<45 beats per minute [bpm]) and hypotension with an associated 16% incidence of cardiac arrest. Animal models have shown hypotension can exacerbate spinal cord ischemia and worsen neurologic outcome. Extensive class III data supports blood pressure augmentation to maintain mean arterial pressure (MAP) at 85 to 90 mmHg for 5 to 7 days postinjury. This therapy can be sustained with minimal morbidity and has shown improved outcomes compared to historical controls. Hypotension and hypoxia should be avoided at all costs.

C.

Other medical issues to be considered in patients with SCI include prevention and treatment of pulmonary complications. Aggressive pulmonary toilet, specialized rotating beds, and antibiotics are often appropriate. Early tracheostomy can reduce length of stay and facilitate care. After evaluating 178 patients with ASIA A SCI, 70% required a tracheostomy; 100% for injuries at or above C3 and none at or below C8. Urinary tract infections are common in paralyzed patients because of repeated catheterization. Decubitus ulcers can occur rapidly in insensate patients. Aggressive nursing care is the mainstay of treatment. Stress gastric and duodenal ulcers are common and prophylaxis is recommended. Joint con-tractures and heterotopic ossification are common in paralyzed patients. These complications can be reduced by physical therapy. SCI patients are more sensitive to acetylcholine and the use of succinylcholine can precipitate a hyperkalemic crisis. Autonomic dysreflexia occurs in up to 90% of patients with lesions above T6. Distension of hollow viscera or cutaneous stimulation can produce rapid fluctuations in blood pressure, vasoconstriction, bladder spasm, flushing, sweating, encephalopathy, seizures, congestive heart failure, and arrhythmias. Treatment involves removal of the stimulus and aggressive blood pressure control.

D.

The risk of deep venous thrombosis (DVT) and pulmonary embolus (PE) are 39% to 100% and 4% to 10%, respectively. Unfractionated or low-molecular-weight heparin and serial compression devices should be instituted as soon as medically feasible. These interventions provide a 50% reduction in incidence of thromboembolism.

E.

Patients with suspected vertebral artery injury should have a CT, MR, or catheter-based angiogram. The lower sensitivity of a computed tomography angiography (CTA) is balanced by the ease with which it is obtained, particularly for unstable patients or those receiving CT imaging of other regions.

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Indications for angiogram include a complete cervical spine injury, fracture of the foramen transversarium, facet dislocation, subluxation, or suspicious neurologic exam. Symptomatic injuries presenting with a stroke may be antico-agulated for 3 to 6 months. Asymptomatic patients should be observed and followed closely as delayed ischemia is common. Antiplatelet agents remain a viable option that will require further study, particularly for asymptomatic patients.

F.

Obtunded patients represent a particular dilemma. Prolonged cervical immobilization has been associated with decubitis ulcers, elevated ICP, pain, and pulmonary complications. Patients who have suffered neurologic injury rendering them comatose or who have other conditions that prevent them from fully cooperating with the examining physician should have complete spine radiographic evaluation. Approximately 1% of patients who are obtunded will have ligamentous instability that is missed when x-ray studies are normal. Classically, passive flexion-extension under fluoroscopy with negative plain films was utilized to rule out instability. However, visualization is inadequate in up to 30% of patients. Combined with the rare but serious potential for permanent morbidity, MRI has emerged as the study of choice to clear the cervical spine in this population. Protocols designed with limited, specialized imaging sequences can reduce time in the scanner and ultimately cost when applied routinely. Sensitivity may be increased by imaging within 48 hours to maximize visualization of edematous tissue. Without access to MRI, a collar can be left in place for 30 days, allowing time for occult ligamentous injury to heal.