Spinal Trauma



Spinal Trauma


Sreeharsha V. Nandyala, MD

Nicholas T. Spina, MD


Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Dr. Nandyala and Dr. Spina.





ABSTRACT

Spinal trauma represents a complex set of injuries from the occiput to the sacrum. These fracture patterns largely result from high-energy trauma, yet a growing number of injuries that have resulted from low-energy mechanisms are being seen in the aging population (older than 65 years). Initial man-agement includes physical examination, stabilization, and advanced imaging. Treatment decisions remain complex and require an understanding of the mechanism of injury, fracture morphology, and the integrity of the secondary ligamentous stabilizers of the spine. Several classification systems have been introduced to establish a common language between providers and allow for high-quality research. Injury severity scoring systems have been developed to guide surgical versus nonsurgical treatment. It is important to provide a framework for the evaluation and treatment of spine trauma.

Keywords: cervical; lumbar; spine; thoracoulumbar; trauma


Introduction

Spinal trauma creates significant burden to the general population and healthcare system. Spinal injuries are typically the result of high-energy blunt trauma or low-energy falls in the growing population of patients older than 65 years. Treatment decisions are complex and take into account many considerations including location of injury, fracture stability, medical comorbidities, other traumatic injuries, bone health, and the long-term implications of spinal fusion. It is important for surgeons to be up to date on the evaluation, diagnosis, and management of cervical and thoracolumbar spinal trauma.


Evaluation

Any patient being evaluated for spinal trauma should first undergo standard Advanced Trauma Life Support evaluation in the emergency department. The force required to generate spinal fractures is often large, and concomitant head, chest, intra-abdominal, and other orthopaedic injuries are quite common. The secondary trauma survey includes spinal assessment after hemodynamic stability is ensured.

Patients should be examined for signs of blunt trauma, such as the seat belt sign or abdominal bruising that are associated with thoracolumbar injuries. The cervical and thoracolumbar spine should be palpated for areas of tenderness, step-off, or bogginess between spinous processes that may indicate injury to the posterior ligamentous process. After inspection and direct palpation, a proper neurologic examination can be performed with the aid of the American Spinal Injury Association form to assess light touch, pinprick sensation, motor strength, deep tendon reflexes, bulbocavernosus reflex, and perianal sensation. Careful rectal examination can provide a prognosis of a spinal cord injury (SCI).1 For example, an intact S4-5 pinprick sensation at 72 hours indicates favorable return of bladder function.2 Spinal shock is characterized by flaccid paralysis, which can be transient. The return of the bulbocavernosus reflex indicates functional spinal arc reflex transmission and an end to a spinal shock.3


Imaging

Obvious spinal injuries may be identified on preliminary chest and pelvis radiographs obtained in the trauma bay as part of a primary trauma survey. Plain radiography largely has been supplanted by CT of the spine. However, in low-energy trauma, initial radiographs
may be obtained. Plain radiographs of the cervical spine may only be accepted as satisfactory examinations if the cervicothoracic junction and C7-T1 disk space can be seen. Radiographs should be obtained in a seated or upright position to avoid missing subtle instability that may reduce when the patient is supine. Once a fracture is identified, CT is recommended to better see and characterize the nature of the injury. Noncontiguous spinal injuries occur in up to 20% of traumas, and, therefore, full spinal axis imaging is required.4 Providers should consider MRI for any patient with a neurologic deficit to better characterize ligamentous injury in some fracture patterns or in certain patients in whom a neurologic examination is not possible.


Spinal Cord Injury

SCI is associated with a chronic loss of function, and treatment incurs significant healthcare expenditures. The rate of SCI per one million people has remained relatively consistent over the past 30 years, but the overall yearly cases have been growing in line with the population. A study that used the US Nationwide Inpatient Sample database identified an incidence of 54 cases per million people and 3,363 total cases of SCI in 2012.5 The most common sources of injury were falls, motor vehicle collisions, and gunshot wounds. During 1993 to 2021, a trend existed toward an increasing number of SCIs associated with falls in patients older than 65 years.5

SCI pathophysiology is a biphasic mechanism. The first phase occurs from direct impact or trauma to the spinal cord. The second phase occurs after the mechanical trauma and is secondary to ischemia and presumed vascular disruption inciting an inflammatory response. The trauma is not modifiable, and therefore much of the ongoing SCI research is aimed at reducing the inflammatory response in the 48 hours after injury. Two mechanisms of treatment are being explored—neuroprotective and neuroregenerative. Neuroprotective treatment reduces the secondary inflammatory response and the neuroregenerative enhances the spinal regeneration pathways. Several clinical trials are currently underway, but significant advances in the standard of care have not been achieved.6 The mainstays of treatment consist of surgical decompression, stabilization, and supportive care consisting of blood pressure goals for 48 to 120 hours after injury.

The timing of surgical intervention for SCI remains controversial. However, a growing body of literature supports earlier intervention as the gold standard of treatment. A large, pooled 2021 analysis of 1,548 patients with SCI between 1997 and 2017 compared those who had surgery within 24 hours of injury with individuals receiving care after 24 hours.7 Significantly greater improvements in motor score, light touch, pin prick, and overall American Spinal Injury Association grades were seen at 1 year in the early versus late group. Using time to surgery as a continuous variable, a steep decline in total motor score change was noted with increased time to surgery between 24 and 36 hours with a plateau effect after 36 hours. This study strengthens the authors’ recommendation that the earlier the time to intervention the greater the likelihood of improvement.


Cervical Spine Trauma


Upper Cervical Spine Trauma

Upper cervical spine trauma encompasses injuries from the occipital condyles to the C2-3 disk space. The space available for the spinal cord is largest in this region and therefore associated SCI is relatively rare. The upper cervical spine is supported by a complex ligamentous structure including the tectorial membrane and apical, alar, and transverse ligaments.

Fractures of the occipital condyle are the most cephalad injuries treated. Stable injuries can be managed with a cervical collar. The classification scheme is based on the fracture pattern: type I injuries are comminuted fractures; type II injuries are related to shear stresses, with a fracture line extending to the skull base; type III injuries are avulsion fractures at the alar ligament attachment and, if bilateral, may be associated with atlanto-occipital dissociation.

Atlanto-occipital dissociation is a rare but extremely unstable injury that requires urgent intervention. Clinical suspicion should be raised if extreme soft-tissue swelling is seen in the upper cervical region on CT or plain radiography. The diagnosis is made on CT-based incongruity of the occipital cervical joint. Multiple measurements exist to identify this injury, including the Powers ratio, but the Harris lines are most useful in evaluation. MRI is useful to assess the ligamentous stabilizers including the alar ligaments, facet joints, and most importantly the tectorial membrane. If uncertainty exists based on radiographic evaluation, a manual traction test may be performed. If more than 2 mm of translation is seen during manual traction, the injury is deemed unstable. Stable injuries may be managed with external orthoses, whereas unstable injuries require occipital cervical stabilization. Fusion is associated with significant morbidity and loss of motion.

C1 injuries most commonly occur secondary to an axial load, which results in a burst fracture (Jefferson
fracture). Typically, this is a three-part or four-part fracture with injuries to the anterior and posterior ring. Stability of C1 fractures is largely based on upright radiograph or CT measurement of C1 on C2 lateral mass overhang, the rule of Spence. A more unique and rare injury is seen in an isolated C1 lateral mass fracture. If significant displacement is seen, a cock-robin deformity of the neck may result as the occipital condyle settles into the displaced and widened lateral mass fracture. Some authors argue for C1 osteosynthesis surgery with C1 lateral mass screws and a cross connector, thereby reestablishing the ring.8 Most C1 fractures may be managed with an external orthosis.

C2 is the most commonly fractured vertebra in patients older than 70 years. Its odontoid process has a unique blood supply, placing a fracture at an increased risk for nonunion. Odontoid fractures have a high risk of mortality in the elderly population akin to the risk of mortality in hip fractures. The Grauer modification of the D’Alonso and Anderson classification is the most used classification for these injuries. Type I fractures are stable and involve an avulsion injury to the tip of the process. Type II fractures traverse the base of the dens, which is a watershed blood supply region between the vertebral and internal carotid systems. Type III fractures propagate laterally into the bilateral C1-2 joint, creating a greater surface area for healing, and are typically treated in external orthosis.

Surgical versus nonsurgical management of type II odontoid fractures remains controversial. The goal of management is to prevent C1-2 instability, reduce neck pain, and allow for mobilization. Some studies have indicated lower rates of mortality with surgical treatment and higher rates of union. A 2021 long-term study of 282 consecutively treated patients with an average follow-up of 39 months showed higher rates of bony fusion in the surgically treated group, but no difference was seen between surgical and nonsurgical groups when fibrous and bony fusions were combined. In addition, no difference in neck pain was seen at long-term follow-up.9

Hangman’s fractures are a unique fracture pattern seen at the C2 vertebrae representing a fracture of the pars interarticularis of C2. The stability of these fracture patterns is driven largely by an associated injury to the C2-3 disk and fracture displacement. If the C2-3 disk is injured or an atypical pattern is observed in which the fracture extends into the posterior body of C2 with significant angulation, surgical intervention is required. Both C2-3 anterior fusion and C2-3 or C1-3 posterior fusions are accepted treatments for this injury.10


Subaxial Cervical Spinal Trauma

Subaxial cervical trauma represents injuries located between the C2-3 and C7-T1 disk spaces. These injuries are best characterized according to their mechanism of injury, fracture morphology, and associated injury to the tension bands of the spine. The AO Spine subaxial classification system was published in 2016 with the goal of establishing a common language description of C-spine injuries with high interobserver reliability.11

The classification system is based on fracture morphology, injury to the facet, neurologic status, and case-specific modifiers that would affect injury treatment. Type A injuries reflect injuries to the vertebral body without disruption of the tension bands of the spine, type B injuries describe patterns with disruption of either the posterior tension band—classically flexion-distraction type injuries—or anterior tension band—classically extension injuries, and type C injuries represent translational injuries of the spine in any plane. Facet injuries are unique and therefore required a separate descriptor based on the severity of injury and extent of the facet involved. A neurologic status modifier is included based on the extent of neurocompromise.

The AO Spine classification system creates a common language but does not have applicability in terms of management recommendations. The Subaxial Cervical Spine Injury Classification System was first published in 2007 and attempts to classify and guide surgical versus nonsurgical treatment based on a novel scoring system. The system takes into account injury morphology, discoligamentous integrity, and neurologic status (Table 1).

A summative score no higher than 3 denotes nonsurgical management and higher than 5 infers surgical stabilization and decompression if necessary. A score of 4 is indeterminant and left to the discretion of the treating surgeon. Raters of the scoring system agreed 93.3% of the time with the treatment algorithm.

Although the Subaxial Cervical Spine Injury Classification and Severity Score is not always applicable, it provides a framework to analyze and evaluate the stability of an injury. In general, surgical treatment is favored if there is discoligamentous disruption and neurologic compromise.12

Treatment principles for subaxial trauma are based on the risk for displacement, progressive kyphosis, neurologic involvement, and degree of canal compromise. Surgical technique and recommendations have not changed drastically in the past 5 years. Nonsurgical treatment consists of brace immobilization (halo vest, hard cervical collar, and soft collar) based on the severity of injury. Surgical treatment aims to decompress the cervical spinal elements and stabilize the spine with
utilization of both anterior and posterior approaches. A 2021 study comparing anterior with posterior fixation of subaxial spine injuries did not show a difference in health-related quality of life at 2-year follow-up, but increased risk of infection with the posterior approach was noted.13 This study largely parallels what has been written with regard to degenerative cervical pathology.








Anterior-based surgical approaches allow for direct decompression of the spinal canal when anterior pathology is present. Diskectomy and fusion may be undertaken in facet injuries such as unilateral or bilateral facet dislocations when intact vertebral end plates are present and facet fractures are absent. One study demonstrated a 13% failure rate of anterior fixation alone in these injuries, with failure being associated with concomitant end plate and facet fractures.14 A recent scoring system, the Posterior Ligament-Bone Injury Classification and Severity Score, was published in 2021 in an attempt to better guide treatment regarding subaxial fracture-dislocations. It considers the severity of injury to the posterior ligamentous complex (PLC), severity of the alignment or displacement of facet joints, and fractures to the lateral mass. Scores higher than 7 are associated with failure of anterior-only fixation.15

Anterior corpectomy and fusion are used when decompression of the cervical canal is necessary. Recently, the development of expandable cervical cages has made this procedure technically easier secondary to obtaining proper tension and fit with modifiable cage expansion in the space. Single-level corpectomies often function as stand-alone fixation techniques while most authors advocate for 360° stabilization in the setting of multilevel corpectomy. The posterior approach, which uses lateral mass and pedicle screw fixation, allows for decompression of the spine over multiple levels and in reduction of irreducible fracture patterns via facet resection (Figure 1).