Ultrasonographic guidance for perineural injections of the cervical spinal nerves in horses.
Authors: Wood Andrew Douglas, Sinovich Matthew, Prutton James Stephen Winter, Parker Russell Alexander
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Ultrasonographic Guidance for Cervical Spinal Nerve Injections in Horses Cervical spinal nerve compression is a diagnostic and therapeutic challenge in equine practice, and perineural injections offer both diagnostic and therapeutic potential if delivered accurately. Wood and colleagues evaluated the precision of ultrasound-guided injection targeting the ventral rami of cervical spinal nerves at the C4/5 and C5/6 intervertebral foramina using an ex vivo cadaveric model (40 injections across 10 horses), employing a 3.5-MHz curvilinear probe positioned vertically to identify the articular process joint before advancing ventrally to visualise the intervertebral foramen. Direct infiltration of the target ventral ramus was achieved in 73% of attempts, with a further 15% landing within 0.5 cm—meaning 88% of injections achieved clinically acceptable accuracy—whilst mean distances of 2.4 cm and 0.9 cm from the spinal cord and vertebral artery respectively suggest an acceptable safety margin, though one arterial penetration was recorded. For practitioners experienced in cervical articular process scanning, ultrasound guidance appears to offer a reproducible and reasonably safe approach to perineural injection at these caudal cervical levels; however, the technique's clinical efficacy, the learning curve required to achieve consistent accuracy in live animals, and strategies to mitigate vascular contact warrant further investigation before widespread adoption in clinical cases.
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Practical Takeaways
- •Ultrasound-guided perineural injections at the cervical spine offer a precise, minimally invasive alternative to landmark-based techniques, with good safety margins from vital structures when performed by experienced sonographers
- •This technique requires competency in cervical spine ultrasound and should be reserved for operators with established scanning skills—it is not a beginner procedure
- •The small but real risk of vertebral artery penetration (2.5% in this cadaver study) means strict aseptic technique, careful needle advancement under real-time ultrasound, and operator expertise are essential before clinical application
Key Findings
- •Ultrasonographic guidance achieved direct infiltration of the ventral ramus in 73% of injections (29/40), with 88% of injections within 0.5 cm of target
- •Mean distance from spinal cord was 2.4 cm (range 0.8–4 cm), indicating a safety margin from neural tissue
- •Mean distance from vertebral artery was 0.9 cm (range 0–1.5 cm), with only one iatrogenic arterial penetration observed
- •Technique is repeatable and accurate when performed by operators experienced in cervical articular process joint ultrasonography