Ultrasound-Guided Injections of Cervical Nerve Roots (C3-C8) in Anesthetized Horses. Fouquet G1, Abbas G1, Johnson JP1, Pompermayer E1, Harel CM1, Aldous E1, Puchalski S2, David F1. 1Equine Veterinary Medical Center, Qatar Foundation, Doha, Qatar; 2Puchalski Equine Diagnostic Imaging, Petaluma, CA.
Despite being a difficult diagnosis, radiculopathy occurs in horses and can cause forelimb lameness when involving C6-C7-C8-T1 cervical nerve roots (CNR), with no reported treatment options. Study
Purpose: To describe an ultrasound-guided injection of C3 to C8 CNR, to evaluate technique accuracy, time, and safety, and to anticipate possible complications on clinical horses. Under general anesthesia, CNR of five horses (C3 to C8) were injected with a latex-contrast mix using ultrasound guidance. After euthanasia, CT examination was performed immediately followed by dissection of the necks three days later. Data regarding accuracy of injection, presence of injectate in nerve root, vertebral vessel or canal were recorded from CT scans and dissections. Out of 60 intended injections, 55 and 57 led to injectate deposited within the target zone based on CT images and dissection, with direct contact between contrast/latex and CNR noted in 76.4% and 73.7%, respectively. Presence of contrast/latex injectate within nerves (≤ 11%), vertebral vessels ( < 4%) and canal ( < 4%) were rarely encountered. The technique described has excellent accuracy, with injectate deposition in direct contact (approx. 75%) or close vicinity (approx. 25%) of C3–C8 CNR. Injectate diffusion is likely to further improve success rate. Rare presence of injectate within nerve/sheath, vertebral vessels/canal along with diffusion warrants caution when performing this procedure in clinical cases. No evaluation of diffusion and use of asymptomatic, anesthetized horses are limitations. The technique described here is very accurate and safe to inject C3–C8 CNR in anaesthetized horses. Further studies are required before it can be used in sedated and symptomatic horses.