What is the Subaxial Injury Classification (SLIC) system for cervical trauma?

The Subaxial Injury Classification (SLIC) System for Cervical Trauma

The Subaxial Injury Classification (SLIC) System and Injury Severity Score provides level I evidence with excellent reliability and class I recommendations for grading instability and fracture patterns in patients with cervical spinal traumatic injury. 1

Core Components of the SLIC System

The SLIC system identifies three major injury characteristics to describe subaxial cervical injuries:

• Injury Morphology: Assesses the pattern of bony and soft tissue injury, with points assigned based on severity 2

  • Compression (1 point)
  • Burst fracture (2 points)
  • Distraction (3 points)
  • Rotation/translation (4 points)

• Discoligamentous Complex (DLC) Integrity: Evaluates the status of the supporting ligamentous structures 2, 3

  • Intact (0 points)
  • Indeterminate (1 point)
  • Disrupted (2 points)

• Neurological Status: Incorporates the patient's neurological condition, a critical factor absent in earlier classification systems 2, 4

  • Intact (0 points)
  • Root injury (1 point)
  • Complete cord injury (2 points)
  • Incomplete cord injury (3 points)
  • Continuous cord compression (+1 point)

Clinical Application and Decision-Making

• The sum of scores from the three major components constitutes the injury severity score, which guides treatment decisions 4, 5

  • SLIC score of 0-3: Conservative management recommended
  • SLIC score of 4: Borderline, surgeon discretion advised
  • SLIC score of ≥5: Surgical intervention recommended

• Patients with SLIC scores 1-3 typically have intact neurological status with minor fractures (spinous process, laminar, or small facet fractures) and are managed conservatively 6

• Patients with SLIC scores 5-10 include those with distraction and rotational injuries, traumatic disc herniation with neurological deficit, and burst fractures with incomplete neurologic deficit, requiring surgical intervention 6

Advantages of the SLIC System

• Incorporates neurological status, which was absent in earlier classification systems, providing more comprehensive assessment 2, 3

• Demonstrates excellent reliability with intraclass coefficients (ICC) for the three primary components ranging between 0.49 and 0.90, superior to conventional classification schemes (ICC between 0.41 and 0.53) 3

• Assists clinicians in managing complex cervical fracture-dislocation injuries by providing guidance on the need for decompression, realignment, and stabilization 1

• Prospective validation has shown the SLIC system to be safe and effective in guiding surgical treatment decisions for subaxial cervical spine trauma 4

Clinical Significance and Implementation

• The SLIC system overcomes limitations of earlier classification systems (Harris, Allen) which demonstrated low reliability with low intraclass correlation coefficients 1

• Use of the SLIC system can assist in determining whether patients require surgical decompression of the spinal canal and cord, followed by spinal realignment and stabilization 1

• While the SLIC system provides guidance on the need for surgical intervention, it does not offer specific recommendations for detailed surgical management approaches 1

• The system is designed to be simple to apply while providing both diagnostic and prognostic information 2

Cautions and Limitations

• The SLIC system does not provide specific recommendations for detailed surgical management, including approach selection (anterior, posterior, or combined) 1

• While the system guides the need for surgical intervention, specific treatment strategies remain variable based on fracture pattern, associated characteristics, institutional resources, and surgeon preferences 1

• Careful assessment of all three components is essential for accurate classification and appropriate treatment planning 5, 3