Blunt Cerebrovascular Injury (BCVI): Universal Imaging for All?

Background: Blunt cerebrovascular injury (BCVI) is defined as carotid or vertebral artery injury due to blunt trauma.  There are several screening criteria that have been developed to screen for this injury, however a significant number of patients may still be missed by these screening criteria. Although this is not a common injury, the potential complications if undiagnosed and untreated can be devastating. Current screening criteria (see below) have been refined and expanded over the years, but just how good are they?

Paper: Leichtle SW et al. Blunt Cerebrovascular Injury: the case for Universal Screening. J Trauma Acute Care Surg 2020. PMID: 32520898

Clinical Question: Does a universal screening protocol for BCVI with CTA of the neck for all major trauma activations perform better than current screening protocols?

Summary of BCVI Screening Guidelines:

Table from American College of Surgeons Trauma Quality Improvement Program (ACS-TQIP) Best Practices Guidelines in Imaging (Link is HERE)

Institutional Screening Criteria (Based on the Expanded Denver Criteria):

Denver BCVI Grading Scale:

• 1 = Intimal irregularity with <25% narrowing
• 2 = Dissection or intramural hematoma with >25% narrowing
• 3 = Pseudoaneurysm
• 4 = Occlusion
• 5 = Transection with extravasation of contrast

Treatment of BCVI Injuries:

• Grade 1 and 2 = Single antiplatelet agent (aspirin 81mg or 325mg)
• Grade 3 = dual antiplatelets or therapeutic anticoagulation (heparin drip with a PTT goal of 60 to 90)
• Grade 4 = Dual antiplatelets or therapeutic anticoagulation used on case-by-case basis with input from neurosurgery

What They Did:

• Retrospective observational trial
• Adult blunt trauma activations from July 2017 to Aug 2019 underwent CT angiography of the neck
• Calculated sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of common screening criteria
• Identified independent risk factors for BCVI

Outcomes:

• Sensitivity, specificity, PPV, NPV, and accuracy of common screening criteria
• Independent risk factors for BCVI

Inclusion:

• All major adult blunt trauma activations
• Enrolled in the VCU trauma registry

Exclusion:

• <18 years of age
• Prisoners
• Pregnant patients
• CTA neck results not available

Results:

• 4,659 patients fulfilled inclusion criteria
  • 126 patients (2.7%) BCVIs
    • 61 (48%) had BCVI grade ≥3
    • No grade 5 BCVI
  • Of the 126 patients with 158 BCVIs 72% (n = 91) would have met the screening criteria outlined in the ACS-TQIP Best Practices Guidelines in Imaging
  • Of the 126 patients with 158 BCVIs 83% (n = 104) would have met the screening criteria outlined in the expanded Denver criteria

• American College of Surgeons Trauma Quality Improvement Program Best Practices Guidelines:
  • Sensitivity: 72.2%
  • Specificity: 64.9%
  • PPV: 6.8%
  • NPV: 98.5%
  • Accuracy: 65.2%
• Denver Criteria:
  • Sensitivity: 82.5%
  • Specificity: 50.4%
  • PPV: 5.3%
  • NPV: 98.9%
  • Accuracy: 51.4%
• 23% (n = 14) of patients with BCVI grade ≥3 would not have been captured by any screening criteria
• Patients who did not receive treatment had a trend toward increased mortality of 52.4% (11 patients) vs patients who received treatment who had a mortality of 4.8% (5 patients)
• Strongest predictors of BCVI:
  • Cervical spine fracture: OR 8.1 (95% CI 5.4 to 12.1)
  • Facial fracture (LeFort II and III): OR 5.7 (95% CI 2.2. to 15.1)
  • Skull base fracture: OR 2.7 (95% CI 1.5 to 4.7)
• 83% (n = 105) patients with BCVI received antiplatelet agents or therapeutic anticoagulation
  • 4% (n = 5) experienced bleeding complications
  • 3% (n = 4) experienced BCVI progression
  • 8% (n = 10) experienced a stroke

Strengths:

• Asks a clinically important question
• Recognizes BCVI remains an important but under-identified problem
• Evaluated the two most extensive and widely used screening criteria in the US 

Limitations:

• This study used 128-slice CT scanners which may not be available at every institution
• Even though a larger number of patients in the “no treatment” group died from severe TBI, the study was not powered to compare complications between the different treatment regimens.Additionally, due to the low incidence of BCVI-related complications the authors were not able to draw statistically valid conclusions
• Hemodynamically unstable patients who did not undergo CT scan upon arrival were excluded and could result in selection bias
• Not all patients with equivocal findings for BCVI on initial CTA neck received follow-up
• No long-term outcomes were available due to inconsistent follow up
• Excluded pregnant patients and therefore risk vs benefit will have to be balanced in these patients

Discussion:

• The concerns of missed BCVI by current screening criteria was also raised in a European single-center study of 4,104 patients with a BCVI incidence of 2.2% and sensitivity of these clinical screening criteria ranging from 57 to 84% [2]
• Many patients will have equivocal findings which represent a real challenge as this can lead to excessive additional diagnostic workup or overtreatment
• In this trial a 48hr follow up CTA of equivocal findings, resulted in a final diagnosis in all but 0.6% cases
• The authors also bring up the potential though overstated risk of contrast induced acute kidney injury and state that there was no increase in this diagnosis which was demonstrated by looking at the incidence in the 18 months before (1%) and 18 months after (0.8%) implementation of universal BCVI screening when reviewing their own ACS TQIP data.
• Antithrombotic therapy and anticoagulation sound counterintuitive in BCVI, but its purpose is to reduce the rate of stroke. It does not necessarily decrease the progression of BCVI. A comparison of treatment regimens is difficult as every institution will have their own practice pattern:
  • Single vs dual antiplatelets
  • 81mg vs 325mg aspirin
  • Antiplatelets vs heparin drip
  • PTT goals

Author Conclusion: “Almost 20% of patients with BCVI, including a quarter of those with BCVI grade 3 or higher, would have gone undiagnosed by even the most extensive and sensitive BCVI screening criteria.  Implementation of universal screening should strongly be considered to ensure the detection of all clinically relevant BCVIs.”

Clinical Take Home Point: The two most commonly used screening criteria, at this single institution missed almost 20% (1 in 5) of patients with BCVI. Although a rare diagnosis, missing it can be catastrophic for the patient. Universal CTA of the neck in hemodynamically stable blunt trauma patients (outside of those with highly unlikely mechanisms such as isolated extremity injuries) will catch all BCVIs with a substantial benefit and very little harm.

References:

1. Leichtle SW et al. Blunt Cerebrovascular Injury: the case for Universal Screening. J Trauma Acute Care Surg 2020. PMID: 32520898
2. Muther M et al. Diagnostic Accuracy of Different Clinical Screening Criteria for Blunt Cerebrovascular Injuries Compared with Liberal State of the Art Computed Tomography Angiography in Major Trauma. J Trauma Acute Care Surg 2020. PMID: 32195997

Post Peer Reviewed By: Zaf Qasim, MD (Twitter: @ResusOne)