The vertebral artery loops: a systematic review and meta-analysis

Area of Science:

• Neurosurgery
• Vascular Anatomy
• Radiology

Background:

• Vertebral artery loops (VALs) represent focal deviations in the vertebral artery's course.
• These loops can cause pulsatile nerve-root compression and increase the risk of iatrogenic vascular injury during cervical spine procedures.
• VALs are considered a
• Purpose of the Study
• Main Methods
• Main Results
• Conclusions

Purpose of the Study:

• To estimate the pooled prevalence of vertebral artery loops (VALs).
• To explain the wide variation in previously reported prevalence figures for VALs.
• To develop a practical framework for preoperative decision-making in cervical spine surgery based on VAL prevalence data.

Main Methods:

• A systematic literature search was conducted following PRISMA guidelines across PubMed, Web of Science, and Google Scholar.
• Ten primary studies involving 7,475 vertebral arteries (VAs) were included in a meta-analysis of proportions.
• A random-effects model was used, with heterogeneity assessed and explored via subgroup analysis based on study methodology.

Main Results:

• The pooled prevalence of VALs was estimated at 1.71% (95% CI 0.87%-2.55%), with significant heterogeneity (I² = 93.4%).
• Subgroup analysis revealed that methodological differences explained the heterogeneity, with radiological imaging cohorts showing 1.09% prevalence versus anatomical series.
• A robust prevalence of approximately 1-2% was confirmed in unselected radiological populations, with clinically relevant loops often located in the V2 segment (C4-C6).

Conclusions:

• Vertebral artery loops (VALs) are uncommon but pose a disproportionately high risk in cervical spine procedures.
• The pooled prevalence serves as a baseline pre-test probability, significantly elevated by indirect osseous signs.
• Preoperative imaging (CTA/MRA) and operative corridor modification are warranted when specific osseous signs are present or complex procedures are planned.