13.1 Epidemiology

Traumatic spinal cord injury (SCI) is a major cause of severe neurological disability. It is estimated that there are approximately 200,000 cases of SCI annually worldwide from accidents and violence.¹ In the United States, the annual incidence of SCI is approximately 54 cases per million population or approximately 17,000 new cases each year,² with a 4:1 male preponderance. Land vehicle crashes are the leading cause of injury, followed by falls and violence (primarily gunshot wounds). Incomplete tetraplegia is currently the most frequent pattern of injury, followed by incomplete paraplegia, complete paraplegia, and complete tetraplegia. Many individuals with complete high cervical injuries or multiorgan injuries do not survive to receive medical attention and are excluded from these statistics; however, one-half of all SCI involve the cervical spinal cord and produce tetraplegia or tetraparesis.

13.2 Mechanisms of Injury

Traumatic fractures, ligamentous injuries, bony translocation, and direct penetrating injury can result in damage to the spinal cord or conus medullaris. This can range from mild contusions with transient (albeit sometimes profound) neurologic deficits to complete transection of the spinal cord with irrecoverable deficits below the level of injury. Infarction, traumatic disc herniation, stretch injuries, or ligamentous buckling or meningeal rupture can also occur. Blunt or penetrating abdominal trauma with disruption of the blood flow from the aorta or its segmental branches can also produce severe SCI. Myelopathy can extend multiple levels superiorly above the site of compression owing to edema from compression and vascular compromise.

13.3 Neurologic Presentation

Lower motor neuron paralysis at and below the level of the injury is the most common presentation, although the patterns may be incomplete and asymmetric depending on the degree of SCI. Upper motor neuron signs below the level of the injury may develop at a later time.

The American Spinal Injury Association Impairment Scale (AIS or sometimes, ASIA scale) is used to grade and localize SCI with acceptable interrater reliability.^3–5 The severity of injury is denoted by a letter (Table 13.1). An AIS grade of A represents complete loss of motor and sensory function below the level of the lesion, and these cases occur predominantly after high velocity injuries with or without cord transection. However, they can also occur with lower velocity injuries when preexisting spine disease or increased spine rigidity is present, such as with ankylosing spondylitis or after extensive spine fusions.

The initial deficits may be exacerbated by the effects of spinal shock and cord hypoperfusion from neurogenic shock.⁶ Neurogenic shock refers to hypotension and poor organ perfusion secondary to interruption of sympathetic autonomic function, resulting in a loss of vasomotor tone, bradycardia owing to unopposed parasympathetic action, and hypothermia. This hypotension can cause secondary SCI from ischemia and should be promptly reversed. As cord perfusion improves, deficits on examination may improve. In contrast, spinal shock refers to acute stunning of the spinal cord manifested by profound loss of spinal cord function near and distal to the level of injury, including areflexia and autonomic failure.^{7, 8} Substantial short-term recovery may occasionally occur after resolution of spinal shock, although this occurs more often in younger patients with an initial discrepancy between severe clinical deficits and less severe radiological findings.

13.4 Initial Management of Acute SCI

The initial steps in management include stabilization of the airway, breathing, and circulation, which may be impaired owing to either SCI or associated trauma (i.e., traumatic brain injury, thoracic or abdominal injuries) as well as total spine immobilization with allowance for preservation of any chronic kyphotic deformity. A CT scan of the spine should always be obtained when there is a possible spine injury and the patient has neurological deficits, so as to exclude fractures or gross ligamentous instability warranting surgical evaluation and intervention or bracing. In high energy trauma, an emergent CT scan of the head and torso should also be obtained. Hemodynamic augmentation is recommended to maintain a mean arterial pressure of 85 mmHg or greater for the first 7 days after SCI to minimize secondary injury, though the evidence supporting this recommendation is rather weak.^9–11 The routine use of high-dose methylprednisolone is associated with harmful side effects and is no longer recommended.¹²

Emergency surgery is warranted for mass lesions compressing the spinal cord, such as spinal epidural hematoma or compressive fracture and disc fragments. Otherwise, stabilization of the fractured and unstable spinal column by means of spinal fusion surgery or bracing should be undertaken, ideally within 24 hours of the injury. Until then, the patient should be kept on spinal precautions including strict bedrest, log rolling with turns, and cervical immobilization.

13.5 Discussing Surgical Treatment

When spinal cord compression is ongoing, early surgical decompression is the preferred course of action.¹³ The discussion of the need for surgical decompression is often the first decision that gets to be shared with the patient or their surrogates. This discussion inevitably involves considerations of prognosis. Yet, at this early stage, it should be acknowledged that often prognosis cannot be estimated with any certainty.

In the absence of other severe injuries, the patient is often able to provide informed consent and has decision-making capacity. For high cervical injuries and other conditions requiring mechanical ventilation, sedation should be held if feasible to obtain informed consent. When the patient is unable to provide it, consent should be obtained from a surrogate decision maker if one is reachable without undue delay. Otherwise, the physician and surgeon must act in the best interests of the patient guided by the ethical principle of nonmaleficence.

When informing patients or surrogates about the purpose of spine surgery, it should be made clear that decompression may help to improve the deficits, but often the main objective is spine stabilization to prevent further cord injury. When providing consent, patients or their surrogates should not do so expecting postoperative resolution of the deficits. The safety of the surgical intervention based on age, comorbid conditions, and clinical stability should also be reviewed. At the conclusion of the discussion, it should be decided whether the surgery is congruent with the overarching goals of the patient.

Individual factors should be considered when deciding whether to offer surgery. In patients with poor bone quality from osteoporosis or spondyloarthropathy, or any patient with multilevel spinal fractures, longer posterior segmental fusions are often required, which result in longer operative times, greater blood loss, and larger surgical wounds. The cohort of patients who are most likely to require a large surgery (i.e., old and frail patients with extensive comorbidities) are often also those at greatest risk of poor wound healing, surgical site infection, perioperative myocardial infarction, venous thromboembolism, or spinal fusion failure and pseudarthrosis, which can progress to hardware and implant failure, as well as subsequent cord injury. These patients may be considered for palliative bracing after an informed discussion about the risks and benefits of surgery and consideration of the patient’s degree of immobility and rehabilitation potential. Alternatively, a more limited surgery or staged surgery may be considered, such as laminectomy for spinal cord decompression alone followed by long-term bracing (i.e., thoracolumbosacral orthosis with or without cervical immobilization or cervical immobilization alone depending on the levels of injury). Long-term bracing is not without risk, because it can lead to skin injuries and ulceration, osteomyelitis, and sepsis. Morbidly obese patients are not good candidates for bracing. Sometimes, the safest treatment is neither surgery nor bracing, and a discussion of the neurological risks and natural history of observation alone is warranted.