Parsing the Utility of CT and MRI in the Subaxial Cervical Spine Injury Classification (SLIC) System: Is CT SLIC Enough?

Subaxial spine trauma: radiological approach and practical implications

The cervical spine is part of the axial skeleton and is responsible for protecting vital structures, such as the spinal cord and the vertebral arteries and veins. Traumatic injury to the cervical spine occurs in approximately 3% of blunt trauma injuries, and approximately 80% are below the level of C2. The AO Spine society divides the spine into four segments: the upper cervical spine (C0-C2), subaxial spine (C3-C7), thoracolumbar spine, and sacral spine. Various classifications have been proposed for the subaxial segment since that of Allen and Ferguson in 1982; however, none is universally accepted, and treatment remains controversial. The complex anatomy and biomechanics of the subaxial spine and the lack of a widely accepted classification system make these injuries difficult to evaluate on imaging. The Subaxial Injury Classification System (SLIC) uses fracture morphology, the integrity of discoligamentous complex, and neurological status to score the patient and determine between operative and non-operative management; however, other factors may influence management, such as time for immobilisation, osteoporosis, surgeon's experience, and hospital circumstances. SLIC classifies fracture morphology in a crescent order of severity based on Allen and Ferguson's classification. Compression fractures are the simpler ones, while both distraction injuries and translation/rotation are severe injuries, which are always associated with some degree of discoligamentous complex (DLC) injury. This article will review the indications for imaging, the basis of the SLIC classification, the different types of fracture morphology, evaluation of the DLC, and other features important in decision making in subaxial spine trauma.

Cervical spine trauma: impact of different imaging classification systems in the clinical decision-making

Background and aim:

Considering the high rate of mortality and permanent disability related to vertebral traumas, an early and detailed diagnosis of the trauma and subsequently an immediate and effective intervention are crucial. Cervical vertebral injury classifications guide treatment choice through a severity grade based on radiological information. The purpose of the present study was to define which imaging classification system could provide the best morphological and clinical-surgical correlations for cervical spine traumas.

Methods:

We retrospectively analyzed patients evaluated for cervical spine trauma at our Institution in the period 2015-2020. Information regarding the morphological examination (using CT and MRI), the neurological evaluation, and the therapeutic management were collected. C3-C7 fractures were classified according to the SLIC and AOSpine criteria; axial lesions were classified according to the modified AOSpine for the C1-C2 compartment and through the Roy-Camille and the Anderson D’Alonzo system for the odontoid process of the axis.

Results:

29 patients were included in the final study population. Nine patients with axial spine trauma and 21 with subaxial cervical spine trauma. A conservative approach was applied in 16 patients while nine patients underwent neurosurgery. Considering the therapeutical indications provided by the SLIC system, a 76.9% accordance was found for patients with a <4 score, while a 100% concordance was calculated for patients with a >4 score undergoing neurosurgery. Regarding the AOSspine classification, a 28.6% concordance was observed for patients classified group B being treated with a posterior neurosurgical approach, while for patients belonging to subgroup C, considered for anterior neurosurgical approach, a 66.7% accordance was calculated.

Conclusions:

The study demonstrated a better morphological correlation for the AOSpine classification in subaxial trauma and the AOSpine and Anderson D’Alonzo in axial trauma. The therapeutic indication found a better correlation in the SLIC classification for subaxial trauma and the Anderson D’Alonzo for axial ones. (www.actabiomedica.it)

Development and first application testing of a new protocol for CT-based stability evaluation of the injured upper cervical spine

PURPOSE

For trauma surgeons, the evaluation of the stability of the upper cervical spine may be demanding. The aim of this study was to develop a protocol for decision-making on upper cervical spine stability in trauma patients based on established parameters obtained by CT imaging as well as testing the protocol by having it applied by trauma surgeons.

METHODS

A structured literature search on upper cervical spine stability was performed. The best evaluated instability criteria in CT imaging were determined. Based on these parameters a protocol for stability evaluation of the injured upper cervical spine was developed. A first application testing was performed. In addition to the assessment of instability, the time required for the assessment was analyzed.

RESULTS

A protocol for CT-based stability evaluation of the injured upper cervical spine based on the current literature was developed and displayed in a flow chart. Testing of the protocol found the stability of the cervical spine was correctly assessed in 55 of 56 evaluations (98.2%). In one test run, a stable upper cervical spine was judged to be unstable. Further analysis showed that this case was based on a measurement error. The assessment time of CT-images decreased significantly during repeat application of the protocol (p < 0.0001), from 336 ± 108 s (first case) to 180 ± 30 s (fourth case).

CONCLUSION

The protocol can be applied quickly and safely by non-specialized trauma surgeons. Thus, the protocol can support the decision-making process in CT-based evaluation of the stability of the injured upper cervical spine.

Posterior Fusion for the Subaxial Cervical Spine: A Review of the Major Techniques

Posterior fusion is a powerful tool to address pathology of the cervical spine, but the decision to fuse at any level should be made with great care. Various methods and constructs for posterior cervical fusion exist, all of which aim to restore the posterior tension band's ability to resist flexion forces. We identified articles regarding posterior fusion of the subaxial cervical spine in MEDLINE, Google Scholar, and PubMed. This article is a narrative review of earlier and current concepts regarding the posterior fusion of the subaxial cervical spine, including wiring, translaminar screws, lateral mass screws, and pedicle screws, weighing the strengths and weakness of the different modalities that the surgeon should bear in mind in creating operative plans individualized to patient pathology.

Influence of Preoperative Magnetic Resonance Imaging on Surgical Decision Making for Patients with Acute Traumatic Cervical Spinal Cord Injury: A Survey Among Experienced Spine Surgeons

OBJECTIVE

Early decompression after acute spinal cord injury (SCI) is recommended. Acute care is crucial, but optimal management is unclear. The aim of this study was to investigate the role of preoperative magnetic resonance imaging (MRI) in addition to computed tomography (CT) in surgical decision making for acute cervical SCI.

METHODS

All patients with cervical SCI between 2008 and 2016 who had preoperative CT and MRI (n = 63) at the Trauma Center Murnau, Germany, were included. We administered a survey to 10 experienced spine surgeons (5 neurosurgeons, 5 trauma surgeons) regarding the surgical management. First, the surgeons were shown clinical information and CT scans. Two months later, the survey was repeated with additional MRI. Corresponding percentages of change and agreement were obtained for each rater and survey item. Finally, results from both parts of the survey were compared with the definitive treatment option (i.e., real-world decision).

RESULTS

MRI modified surgical timing in a median of 41% of patients (interquartile range 38%-56%). In almost every fifth patient (17%), no surgery would have been indicated with CT alone. The advocated surgical approach was changed in almost half of patients (median 48%, interquartile range 33%-49%). Surgically addressed levels were changed in a median of 57% of patients (interquartile range 56%-60%). MRI led to higher agreement with the real-world decision concerning addressed levels (median 35% vs. 73%), timing (median 51% vs. 57%), and approach (median 44% vs. 65%).

CONCLUSIONS

Preoperative MRI influenced surgical decision making substantially in our cohort and has become a new standard for patients with cervical SCI in our institution if medically possible.

Surgical Management of Pediatric Spine Trauma: 12 Years of Experience

OBJECTIVE

Spine trauma management in children varies from one team to another, and to date, no clear consensus has been reached. The goal of this study was to describe the epidemiology of spine trauma in children and evaluate the timing and techniques of surgery when it was required.

METHODS

A retrospective review of all patients admitted to our pediatric trauma center for spine traumas that required surgical management, between 2005 and 2016, was performed. All patients were followed with clinical and radiologic examination to evaluate the quality of fusion and realignment.

RESULTS

Seventy-three children, with a mean age of 14.1 years, were admitted. Spinal injuries were more common in the teenage group (14-18 years). The predominant etiology of spine injuries was motor vehicle collision (36%). The spinal level of injury varied according to the age group: young children presented more cervical traumas (P < 0.01), while teenagers presented more lumbar traumas. There were more fractures alone in the teenage group (P < 0.005), while there were more luxations alone in the school-age group (P < 0.05). Median timing for surgical intervention in patients with neurologic deficits was 1 day. Patients with posterior wall recession >5 mm underwent surgical management quicker than patients with no posterior wall recession (P < 0.03). At follow-up, out of the 37 patients with initial neurologic deficits, 14 had improved (38%).

CONCLUSIONS

Diskoligament maturation is an essential concept in spine traumas in children, as well as in surgical management. Surgical procedures should be carried out as soon as possible when patients present with neurologic deficits. At the thoracolumbar junction, a 2-level up-and-down fixation is recommended.

Subaxial cervical spine trauma

Subaxial cervical spine trauma is common and an often missed diagnosis. Accurate and efficient diagnosis and management is necessary to avoid devastating complications such as spinal cord injury. Several classification schemes have been devised to help categorize fractures of the subaxial spine and define treatment algorithms. The Subaxial Cervical Spine Injury Classification System (SLIC) is widely used and evaluates not only fracture morphology but also considers ligamentous injury and neurological status in surgical decision making. However, interobserver reliability is poor, which proves to be the defining pitfall of this tool. More modern classification systems have been developed, which aim to improve the interobserver reliability; however, further large-scale studies are needed for more definitive evaluation. Overall, treatment of subaxial cervical spine injuries should include a protocol with initial trauma evaluation, leading to expedient operative intervention if indicated. Surgical techniques include both anterior and posterior approaches to the cervical spine depending on fracture classification.

Classification and Management of Pediatric Subaxial Cervical Spine Injuries

Appropriate management of subaxial spine injury in children requires an appreciation for the differences in anatomy, biomechanics, injury patterns, and treatment options compared with adult patients. Increased flexibility, weak neck muscles, and cranial disproportion predispose younger children to upper cervical injuries and spinal cord injury without radiographic abnormality. A majority of subaxial cervical spine injuries can be treated nonoperatively. Surgical instrumentation options for children have significantly increased in recent years. Future studies of outcomes for children with subaxial cervical spine injury should focus on injury classification and standardized outcome measures to ensure continued improvement in quality of care for this patient population.