John Steinmann DO and Gina Cruz DO

1. What are the incidence and leading causes of spinal cord injuries?

It is estimated that 12,000 new cases of spinal cord injury occur each year in the United States. This equates to approximately 40 cases per million population. There is a distinct predominance of male patients, representing 81% of patients enrolled in the spinal cord injury database. The average age of spinal cord injury in the United States for the years 2000 through 2005 was 37.6 years with the past 30 years showing a slow steady increase in the average age of patients sustaining spinal cord injuries. The leading causes of spinal cord injury are:

2. What are the goals in treating a patient with spinal cord injury?

• Safe extrication and transport

• Maintenance of airway, breathing, and circulation

• Prevention of hypoxemia and hypotension

• Accurate identification and classification of spinal injury

• Identification of associated injuries (head, pulmonary, abdominal, long bone injuries)

• Rapid reduction of fractures and dislocations

• Timely stabilization of unstable spinal segments

• Early transfer to an appropriate acute spinal cord rehabilitation center

3. Summarize the important aspects of the prehospital care of the potentially spine-injured patient.

Patients with high-energy mechanisms or altered mental status should be assumed to have sustained a spinal injury and undergo extrication and transport using strict spinal precautions. Treatment begins with ensuring an adequate airway, breathing, and circulation. Prevention of hypoxemia and hypotension through the use of supplemental oxygen, intravenous fluids, and vasopressors helps limit the zone of spinal cord injury. Transport to a facility prepared to manage acute spinal cord injury is essential.

4. Discuss the role of steroids in the treatment of acute spinal cord injury.

Proponents have reported enhanced neurologic recovery in patients with incomplete motor lesions when methylprednisolone is administered within 8 hours of injury. A loading dose of 30 mg/kg is followed by 5.4 mg/kg for 23 hours if administered within 3 hours of injury or for 48 hours if administered between 3 and 8 hours after injury. Contraindications to steroid administration include:

• Patients presenting more than 8 hours following injury

• Injuries limited to the cauda equina or individual nerve roots

• Gunshot wounds

• Uncontrolled diabetes

• Patients on steroid maintenance

Opponents of the use of methylprednisolone in acute spinal cord injury dispute the benefits of this practice, citing risks of steroid administration in polytrauma patients including wound infection, pulmonary embolus, and sepsis. As a result, the use of methylprednisolone in spinal cord injuries is no longer considered standard of care but remains a treatment option.

5. A patient presents with acute quadriplegia following a C5-6 bilateral facet dislocation. The patient has associated minor closed fractures of the extremities and no evidence of injury to any other organ system. The emergency department physician reports that the patient is hypotensive (blood pressure is 78/50 mm Hg)

and bradycardic (pulse is 48 beats/minute). What is the likely etiology of this patient's hypotension?

Both neurogenic and hypovolemic etiologies (as well as a combination of both) should be considered in the trauma setting. In a patient with a severe spinal cord injury who exhibits the combination of hypotension and bradycardia, the more likely etiology is neurogenic shock. A temporary generalized sympathectomy effect decreases cardiac output and peripheral vascular resistance. Treatment often requires the use of vasopressors, and, in severe cases, cardiac pacing is needed. It is important not to confuse this picture with hemorrhagic shock, which presents with hypotension and an increased pulse rate. Increasing fluids will not raise blood pressure in neurogenic shock and instead may cause serious fluid overload and pulmonary edema.

6. In evaluating the conscious patient with spinal injury, what are the important aspects of the history?

The history should establish the mechanism of injury, time of injury, location of pain, loss of consciousness, and, very importantly, the presence of transient or persistent neurologic complaints (sensory and/or motor). In addition, the history should seek to understand the patient's relevant past medical history.

7. What is the importance of a transient neurologic deficit following high-energy trauma?

A stable spine maintains appropriate alignment and protects the neural elements under physiologic loads. A transient neurologic deficit indicates a moment during the injury when the spine failed to protect the neural elements. Although this may be the result of preexistent stenosis, when associated with a high-energy mechanism one must assume an injury has occurred that has rendered the spine unstable.

8. Describe the essential elements of the physical exam in the spine-injured patient.

The primary survey should focus on establishing the presence of adequate airway, breathing, and circulation. The secondary survey involves a general inspection of the entire body, including detailed examination of the spine. The patient is log-rolled, and the spine is inspected and palpated. One should note localized tenderness, bruising, and interspinous widening or displacement. The neurologic examination should follow the Standard Neurological Classification of Spinal Cord Injury form established by the American Spinal Injury Association (ASIA) (Figs. 6-1 and 6-2). A detailed motor, sensory, and reflex exam must include a rectal exam to assess for sacral sparing and the bulbocavernosus reflex.

9. What is sacral sparing? What is its significance in patients with spinal cord injury?

Sacral sparing refers to the presence of perianal sensation after an acute spinal cord injury that has otherwise rendered the patient with complete motor deficit below the level of injury. This finding indicates some degree of transmission of neural impulses across the level of spinal cord injury and signifies that the patient has sustained a partial spinal cord injury, with the potential for some degree of neurologic recovery. Sacral sparing is due to the topographic cross-sectional organization of the spinal cord in which the sensory and motor fibers supplying caudad regions are located laterally and closer to the surface of the spinal cord. Spinal cord contusion and ischemia typically result in greater damage to centrally located tracts than tracts located in the periphery of the spinal cord.

10. Define spinal shock and explain its significance after an acute spinal cord injury.

Spinal shock refers to the period after spinal cord injury (usually 24 hours) when the reflex activity of the entire spinal cord becomes depressed. During this period the reflex arcs below the level of spinal cord injury are not functioning. The return of reflex activity below the level of a spinal cord injury signifies the end of spinal shock. The significance of spinal shock lies in the determination of whether a patient has sustained a complete vs. incomplete spinal cord injury. This cannot be determined until spinal shock has ended. Bulbocavernosus reflex is used to assess the end of spinal shock.

11. What is the bulbocavernosus reflex? What is its significance?

The bulbocavernosus reflex is a spinal reflex mediated by the S2 to S4 cord segments. It is tested by application of digital pressure on the penis or clitoris or gently pulling on the Foley catheter to cause reflex anal sphincter contraction. Absence of this reflex indicates spinal shock. Return of this reflex signifies the end of spinal shock. At this point, the patient with complete loss of motor and sensory function below the level of injury and absence of sacral sparing is considered to have a complete spinal injury.

12. How is the degree of neurologic injury described following an osteoligamentous injury to the spine?

Patients are stratified into the following categories:

Neurological^ intact. The patient is awake, alert, and demonstrates normal motor, sensory, and reflex function Root injury. There is evidence of peripheral nerve injury as exhibited by painful dysesthesias and/or motor deficits along an individual nerve root without evidence of sensory, motor, or reflex changes at cord levels below the level of this injury. As a root injury is a peripheral nerve injury, it has potential for recovery

Figure 6-1. American Spinal Injury Association classification of spinal cord injury.

ASIA IMPAIRMENT SCALE

" A = Complete: No motor or sensory function is preserved in the sacral segments S4-S5.

B = Incomplete: Sensory but not motor function is preserved below the neurological level and includes the sacral segments S4-S5.

□ C = Incomplete: Motor function is preserved below the neurological level, and more than half of key muscles below the neurological level have a muscle grade less than 3.

□ D = Incomplete: Motor function is preserved below the neurological level, and at least half of key muscles below the neurological level have a muscle grade of 3 or more.

□ E = Normal: motor and sensory function are normal

CLINICAL SYNDROMES

Central Cord Brown-Sequard Anterior Cord Conus Medullaris Cauda Equina

Figure 6-1. American Spinal Injury Association classification of spinal cord injury.

Figure 6-2. American Spinal Injury Association impairment scale.

Incomplete spinal cord injury. Partial preservation of neural function is noted below the level of injury. Recovery may vary from minimal to complete, depending on the type of incomplete spinal cord injury. Six incomplete spinal cord injury syndromes have been described: (1) central cord, (2) Brown-Sequard, (3) anterior cord, (4) posterior cord, (5) conus medullaris, and (6) cauda equina

Complete spinal cord injury: Absent sensory and motor function more than three segments below the level of injury

13. Describe the Frankel classification of spinal cord injury.

The Frankel classification has been used to separate patients with spinal cord injuries into five functional grades: Grade A: Absent motor and sensory function Grade B: Absent motor function with sensory sparing Grade C: Very weak motor function (not useful); sensation present Grade D: Weak but useful motor functions; sensation present Grade E: Normal motor and sensory function

14. What is the ASIA Impairment Scale for assessing the spinal cord injured patient?

The American Spinal Injury Association (ASIA) Impairment Scale provides a more detailed method for classifying the neurologic status of patients with spinal injuries:

ASIA A: Complete injury. No motor or sensory function distal to the level of injury including the sacral segments S4-S5

ASIA B: Incomplete injury. Sensory but not motor function is preserved below the neurologic level and includes the sacral segments S4-S5

ASIA C: Incomplete injury. Motor function is preserved below the neurologic level, and more than half of key muscles below the neurologic level have a muscle grade less than 3

ASIA D: Incomplete injury. Motor and sensory incomplete (motor functional) with at least half of key muscles below the neurologic level having a muscle grade 3 or 4 ASIA E: Normal; sensory and motor function intact

15. Name the location and function of the major spinal cord tracts important in the assessment of the patient with spinal cord injury.

Corticospinal tracts: Descending tracts originate in the primary motor cortex, cross within the brainstem, descend within the anterior and lateral portion of the cord, and terminate directly on motor neurons in the ventral gray matter of the spinal cord. These tracts transmit ipsilateral fine motor movement. Injury to the corticospinal tracts leads to loss of fine motor function ipsilateral to the cord injury Spinothalamic tracts: Ascending tracts located in the anterolateral portion of the cord that transmit sensations of pain and temperature. These tracts cross shortly after entering the spinal cord and, therefore, transmit sensation from the contralateral side of the body Dorsal column tracts: Ascending tracts that convey proprioceptive, vibratory, and discriminative touch sensation. Fibers originate in the dorsal root ganglion, ascend the ipsilateral dorsal column, and cross within the brainstem. Lesions to the dorsal column tracts result in loss of proprioception and vibratory sense ipsilateral to the injury

16. Briefly explain the mechanism and clinical presentation of the incomplete spinal cord injury syndromes involving the cervical spinal cord.

Central cord syndrome is the most common incomplete spinal cord injury syndrome. It is often seen in elderly patients with preexisting cervical stenosis who sustain a hyperextension injury. The clinical presentation includes bilateral sensory and motor deficits with upper extremity weakness greater than lower extremity weakness. Lower extremity hyperreflexia and sacral sparing are noted. The prognosis is good for a partial recovery. Recovery of hand function is generally poor. Typical management of central cord syndrome is initiated with traction and immobilization for a period to allow early recovery and diminish spinal cord edema followed by decompression of the preexisting stenosis and stabilization of the injured level.

Brown-Sequard syndrome is caused by a hemisection of the spinal cord. The clinical presentation includes ipsilateral motor and proprioception loss with contralateral pain and temperature loss distal to the level of injury. The prognosis for recovery is good, with most patients recovering some degree of ambulatory capacity and bowel and bladder function. Common causes include knife wounds, missile wounds, and asymmetrically located spinal cord tumors.

Anterior cord syndrome results from vascular ischemia or compression of the anterior spinal artery and anterior spinal cord. Typically, neural function is absent in the anterior two-thirds of the spinal cord. Findings include complete loss of motor function and pain and temperature sensation distal to the site of injury with preservation of vibration and proprioception. The prognosis for recovery is poor. A common causes is a vertebral body fracture associated with spinal cord injury secondary to retropulsed bone. Intraoperative hypotension during complex spinal procedures for cervical myelopathy is an additional potential cause.

Posterior cord syndrome presents with loss of discriminative touch as well as position and vibratory sense. However, motor function and pain and temperature sensations are intact. Patients typically ambulate with a foot-slapping gait. This syndrome is uncommon. Potential causes include vitamin B12 deficiency and syphilis.

17. What is SCIWORA?

SCIWORA refers to spinal cord injury without radiographic abnormality. This syndrome is seen in young children and older adults. In children, the elasticity of the immature spine permits neurologic injury without a fracture. In older adults with preexistent central spinal stenosis, an acute central cord syndrome may develop after a fall despite the absence of a spinal fracture.

18. What initial imaging studies should be obtained in spine-injured patients?

Traditionally, imaging assessment of the polytraumatized patient began with plain radiographs: anteroposterior (AP) chest, anteroposterior (AP) pelvis, and cervical spine (AP, lateral, and open mouth odontoid views). The advent of high-speed spiral computed tomography (CT) scanning has largely replaced routine plain radiographic imaging of the cervical spine. In addition, high-speed CT scanning of the chest, abdomen, and pelvis has largely eliminated the need for AP chest and pelvic radiographs. All polytrauma patients require adequate imaging of the spine (cervical, thoracic, and lumbar), chest, and pelvis, either via plain x-rays or preferably, if facilities allow, high-speed spiral CT imaging. Helical CT imaging of the traumatized spine has greatly increased the sensitivity for identification of spinal injuries.

19. Describe how to evaluate a lateral cervical spine radiograph in a patient following spinal trauma.

Count the number of vertebral bodies that are clearly seen. The lateral view must visualize from the occiput to the superior endplate of T1. Inability to visualize T1 necessitates traction view, a swimmer's view, or a cervical CT scan.

Evaluate the thickness of the retropharyngeal soft tissues. Normal retropharyngeal swelling is up to 3 to 5 mm at C3 and less than 15 mm at C6. Increased soft tissue thickness may indicate a serious injury but absence of swelling does not rule out a significant injury.

Assess subaxial cervical alignment by constructing four parallel lines: anterior vertebral line, posterior vertebral line, spinolaminar line, and posterior spinous process line. Check the relationship of adjacent vertebra at the level of the spinous processes, facet joints, disc spaces, and vertebral margins for potential asymmetry, subluxation, or distraction.

Examine C1-C2 and occiput-C1 alignment. Check the atlantodens interval (normally 3.5 mm in adults and 5 mm in children) as increase in this interval signifies rupture of the transverse ligament. Look for signs of injury involving the atlanto-occipital articulation by checking the dens-basion interval, Wackenheim's line, and Harris lines (see Chapter 55).

20. What are indications for magnetic resonance imaging (MRI) in patients with spinal injury?

• Unexplained neurologic deficit

• Incomplete neurologic deficit

• Neurologic deterioration

• Before reduction of the cervical spine in neurologically intact patients

• Preoperatively in patients scheduled for posterior cervical, thoracic, or lumbar reduction and stabilization

• To assess the degree of spinal cord or ligamentous injury

21. When are cervical flexion-extension views indicated?

Flexion-extension views are to be avoided in the acute setting. In a patient who has normal radiographs and spinal tenderness, a rigid collar should be used for the first two weeks. If tenderness persists, controlled flexion-extension views under physician supervision may help to rule out a ligamentous injury.

22. What are the criteria necessary to clear the cervical spine?

• Conscious, mentally alert, and oriented patient

• Negative, adequate plain radiographs or cervical CT scan

• Absence of localized posterior spinal tenderness

• Intact neurologic status

Key Points

1. Patients with high-energy injury mechanisms or altered mental status should be assumed to have sustained a significant spinal injury and undergo immediate spinal immobilization during extrication, transport, and initial evaluation.

2. The potentially spinal-injured patient is assessed according to Advanced Trauma Life Support (ATLS) protocols.

3. Patients with neurologic injury are assessed according to the Standards for Neurologic Classification established by the American Spinal Injury Association (AsiA).

4. Hypotension and hypoxemia require aggressive treatment in the spinal cord injured patient.

5. The clinical syndromes resulting from spinal cord injury depend on the level of injury and the anatomic tracts involved by the injury.

Websites

1. General trauma evaluation: http://www.fpnotebook.com/ER/Trauma/TrmEvltn.htm

2. Steroids for spinal cord injury: http://www.trauma.org/index.php/main/article/394/

3. American Spinal Injury Association classification worksheet: http://www.asia-spinalinjury.org/publications/2006_Classif_worksheet.pdf

4. Guidelines for diagnosis of suspected spine trauma: http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=11597&nbr=6010

BiBLiOGRAPHY

1. American Spinal Injury Association, International Medical Society of Paraplegia. International Standards for Neurological and Functional Classification of Spinal Cord Injury, Revised 1996. Chicago: American Spinal Injury Association; 1996.

2. Bracken NB, Shepard MJ, Collins WF, et al. A randomized controlled trial of methylprednisolone and naloxone in the treatment of acute spinal cord injury: Results of the Second National Acute Spinal Cord Injury Study. N Engl J Med 1990;322:1405-11.

3. Gupta MC, Benson DR, Keenen TL. Initial evaluation and emergency treatment of the spine-injured patient. In: Browner BD, Jupiter JB, Levine AM, et al., editors. Browner: Skeletal Trauma. 4th ed. Philadelphia: Saunders; 2008.

4. Hurlbert RJ. Methylprednisolone for acute spinal cord injury: an inappropriate standard of care. J Neurosurg 2000;93(1 Suppl):1-7.

5. Kim DH, Ludwig SC, Vacarro AR, et al. Atlas of Spine Trauma. Philadelphia: Saunders; 2008.

6. McCulloch PT, France J, Jones DL, et al. Helical computed tomography alone compared with plain radiographs with adjunct computed tomography to evaluate the cervical spine after high energy trauma. J Bone Joint Surg 2005;87A:2388-94.

7. Mirza sK, Bellabarba C, Chapman JR. Principles of spine trauma care. In: Bucholz RW, Hechman JD, editors. Rockwood and Green's Fractures in Adults. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2006. p. 1401-34.

8. White AA III, Panjabi MM, editors. Clinical Biomechanics of the Spine. 2nd ed. Philadelphia: Lippincott; 1990.

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