European Spine Journal · 2026

The Vertebral Artery Loops: A Systematic Review and Meta-Analysis

A systematic review of vertebral-artery loops that separates frequent radiological reality from outlier anatomical series. The pooled message is that loops are uncommon overall, but clinically important when they remodel local anatomy or enter the differential diagnosis of radiculopathy.

Albu AC · Rusu MC · doi: 10.1007/s00586-026-10221-x

This microsite condenses the paper into interactive reading paths. Use the buttons below to switch between anatomical logic, key findings, and practical implications.

Prevalence

Loops are uncommon, but estimates depend on study type

Across pooled studies the overall prevalence was 1.71%, but radiological cohorts yielded lower pooled values (about 1.09%), while two anatomical outlier series produced far higher estimates. The review therefore emphasises context before quoting a number.

Overall pool

126 loops among 7,475 vertebral arteries, pooled prevalence 1.71%.

Radiological cohorts

Imaging-based cohorts suggested a lower and more clinically realistic prevalence around 1.09%.

Outlier effect

Two anatomical studies disproportionately inflated simple narrative impressions of frequency.

Take-home point: The best reading is that vertebral-artery loops are uncommon yet recurrently relevant variants.

How to read the prevalence

Radiology-led estimateBest guide to real-world imaging prevalence.

Overall pooled estimateUseful summary, but heterogeneous.

Anatomical outliersHigh estimates should not be generalised uncritically.

Meta-analytic interpretation improves when study modality is kept in view.
Not every “rare” lesion on imaging is extremely exceptional, but neither is looping common.
The review curbs overstatement by showing where inflation originates.

Topography

Where loops tend to appear and what they do locally

Most reported loops involved the V2 segment between C4 and C6. Their importance arises less from prevalence than from local effects on the cervical spine and adjacent roots.

V2 predominance

The intertransverse cervical segment was the commonest location.

Bony remodelling

Loops may produce enlarged foramina transversaria or vertebral-body scalloping.

Symptoms

Some loops are incidental; others enter the work-up of radiculopathy, myelopathy, or pulsatile symptoms.

Take-home point: The loop is clinically important because it changes local topography, not because it is numerically common.

Loop consequences

Arterial redundancyThe artery forms a focal detour or loop.

Bony adaptationForaminal enlargement or scalloping may accompany the loop.

Neural relationshipAltered proximity to cervical roots may create or mimic compressive symptoms.

Imaging interpretation should distinguish a vascular loop from tumour, cyst or foraminal mass.
Symptoms depend on level and neighbourhood, not merely on the presence of a loop.
V2 loops remind clinicians that the vertebral artery is an active participant in cervical anatomy.

Clinical use

Surgical and diagnostic implications

The review supports careful preoperative imaging before cervical procedures and a broad diagnostic imagination when unusual foraminal or juxtaforaminal findings appear.

Surgery

Loops may alter screw corridors, dissection planes or foraminal decompression strategy.

Radiology

Recognition prevents misclassification as a pathological mass and encourages vascular-aware reporting.

Education

The review is also a teaching tool in how to read pooled anatomy with heterogeneity in mind.

Take-home point: The review transforms vertebral-artery loops from anecdotal curiosities into a teachable clinical-anatomy topic.

Action points

IdentifyRecognise the vascular nature of the lesion.

LocaliseRecord level, segment, and relation to foramina or roots.

TranslateExplain why the finding matters for surgery or symptoms.

The article is methodologically useful because it demonstrates how a pooled estimate can be distorted by outliers.
Routine CTA/MRA context is more informative than isolated case fascination.
A loop should be described as a topographic variant with potential mechanical implications.