What are the indications for a halo vest in subaxial spine injuries?

Indications for Halo Vest in Subaxial Spine Injuries

Halo vest immobilization should be reserved for select subaxial cervical spine injuries (C3-T1) with a SLIC score of 3-4, particularly isolated fractures without significant ligamentous disruption, though it carries a 15-23% failure rate requiring subsequent surgical fusion. 1, 2, 3, 4

Primary Indications Based on SLIC Scoring

The Subaxial Injury Classification (SLIC) System provides the framework for treatment decisions in subaxial injuries: 1, 2

• SLIC score ≥5: Surgical intervention is indicated, not halo vest 1, 2
• SLIC score 3-4: Halo vest may be considered as non-operative management 1, 2
• SLIC score <3: Rigid cervical collar typically sufficient 1, 2

The SLIC system evaluates three components: fracture morphology, discoligamentous complex (DLC) integrity, and neurological status. 2 Disrupted DLC receives 2 points, complete cord injury 2 points, and incomplete cord injury 3 points. 2

Specific Subaxial Injury Patterns Suitable for Halo Vest

Acceptable Candidates

• Isolated fractures without significant ligamentous injury (intact DLC) 5, 6
• Stable compression fractures with minimal displacement 5, 6
• Selected burst fractures without posterior ligamentous complex disruption 5, 6

High Failure Risk Patterns (Relative Contraindications)

• Locked or "perched" facets: 23% overall failure rate for C3-T1 injuries, with locked facets representing the highest risk subgroup 4
• Bilateral facet dislocations: These typically require surgical stabilization 3, 4
• Subluxations without bone injury: Two of four treatment failures occurred in this group 5
• Significant angulation without fracture: High risk of loss of reduction 5, 3

Absolute Contraindications

Do not use halo vest in the following subaxial injury scenarios: 5, 3

• Complete spinal cord injury with anesthetic skin (risk of pressure ulceration) 5
• Disc or bone fragments within the spinal canal on CT/MRI requiring decompression 5
• Unsatisfactorily reduced subluxations or dislocations 5
• Neurological deficit with progressive deterioration 3

Evidence for Failure Rates

The literature demonstrates concerning failure rates for halo vest in subaxial injuries:

• 40% radiographic instability rate after halo vest treatment alone in one series, with 25% ultimately requiring surgical stabilization 3
• 15-23% overall failure rate across multiple studies for C3-T1 injuries 6, 4
• Two patients experienced neurological deterioration secondary to loss of reduction while immobilized in halo vest 3

In contrast, early operative fusion followed by immobilization showed only 7% instability rate (p<0.01 compared to halo alone). 3

Clinical Algorithm for Decision-Making

Step 1: Calculate SLIC score 1, 2

• If ≥5 → Surgical stabilization
• If <3 → Rigid collar
• If 3-4 → Proceed to Step 2

Step 2: Assess for absolute contraindications 5, 3

• Complete cord injury with anesthetic skin
• Canal compromise requiring decompression
• Unreducible dislocation
• If present → Surgical stabilization

Step 3: Evaluate injury pattern 5, 3, 4

• Locked/perched facets → Surgical stabilization
• Bilateral facet dislocation → Surgical stabilization
• Isolated fracture with intact DLC → Halo vest acceptable
• Pure ligamentous injury → Use with extreme caution or proceed to surgery

Step 4: Assess MRI findings 7, 1

• Significant DLC disruption → Surgical stabilization preferred
• Intact posterior ligamentous complex → Halo vest acceptable

Treatment Duration and Monitoring

• Standard immobilization period: 10-12 weeks (3 months average) 5, 6, 4
• Healing rate at 1 year: 90% for appropriate candidates 6
• Close radiographic monitoring required: Serial imaging to detect loss of reduction 3, 6

Common Complications

Pin-related complications are most frequent (60% pin loosening rate), though usually minor. 6 More serious complications include:

• Loss of reduction requiring surgical conversion (15-40% depending on injury pattern) 3, 6, 4
• Neurological deterioration from inadequate immobilization 3
• Local neck symptoms in 80% at long-term follow-up (usually mild) 6

Critical Pitfall

The halo vest does not absolutely immobilize the cervical spine and does not protect patients with cervical instability from neurological injury. 3 This is the most important caveat when considering non-operative management. Patients with significant ligamentous disruption or complex injury patterns should proceed directly to surgical stabilization rather than risk delayed treatment after halo failure. 3, 4