Ultrasonographic guidance for perineural injections of the cervical spinal nerves in horses

Abstract

Objective: To evaluate the accuracy of ultrasonographic guidance for injection near the ventral rami of the cervical spinal nerves (VRCSN).Study design: Ex vivo study. Sample population: Ten cadavers (n = 40 injections).Methods: Left and right VRCSN at C4/5 and C5/6 were infiltrated at the intervertebral foramen (IVF) under ultrasonographic guidance. A vertically orientated 3.5-MHz curvilinear probe was used to identify the craniocaudal midpoint of the articular process joint (APJ). The probe was moved ventrally until the IVF was identified. An 18-gauge 15-cm-long spinal needle was aimed immediately below the ventral margin of the cranial articular process, where 1 mL of latex was injected. Cadavers were dissected, and the location of the latex was recorded relative to the ventral ramus, the spinal cord, and the vertebral artery.Results: Direct infiltration of the ventral ramus occurred in 73% (29/40) of injections; 15% (6/40) of injections were < 0.5 cm from the ventral ramus, and 13% (5/40) of injections were > 0.5 cm (maximum 1.5 cm). Latex was located at a mean of 2.4 cm (range, 0.8-4) from the spinal cord and 0.9 cm (range, 0-1.5) from the vertebral artery. Conclusion:Ultrasonographic guidance of perineural injections of the caudal VRCSN was repeatable and accurate, with 88% of injections located within 0.5 cm of the ventral ramus. Iatrogenic damage was limited to one penetration into the vertebral artery.Clinical significance: Ultrasonographic guidance of perineural injections of the caudal VRCSN may be considered by operators experienced in cervical APJ scanning in horses with suspected cervical spinal nerve compression.

Ultrasound-guided injection technique of the equine cervical nerve roots

“…Based on the pilot study findings, the ventral branch separates from the cervical nerve root and runs immediately dorsal to the vertebral blood vessels. Other studies have shown that direct visualization of the nerve is not necessary to obtain good results and other specific landmarks can be used such as immediately below the ventral margin of the cranial articular process (transducer parallel to the short axis of the neck) or the region between the APJ and the vertebral body (transducer parallel to the long axis of the neck) ( 12 , 13 ). It is however highlighted that a good understanding of the anatomy and structures within and surrounding the IVF is required to perform this procedure successfully and safely ( 12 , 13 ).…”

“…Multiple cadaveric studies have been performed in horses aiming at developing UG injection techniques of the cervical nerve roots and showed promising results ( 11 – 14 ). The study performed by Wood et al had a 73% success rate with direct contact between the injectate and the ventral ramus of the targeted cervical nerve root ( 13 ). This study focused on injecting C5 and C6 and the skin of the cadavers was removed prior to performing the injections, which altered the conditions compared to live horses ( 13 ).…”

“…The study performed by Wood et al had a 73% success rate with direct contact between the injectate and the ventral ramus of the targeted cervical nerve root ( 13 ). This study focused on injecting C5 and C6 and the skin of the cadavers was removed prior to performing the injections, which altered the conditions compared to live horses ( 13 ).…”

Percutaneous full endoscopic foraminotomy for treatment of cervical spinal nerve compression in horses using a uniportal approach: Feasibility study

“…The spinal nerve traverses dorsal to the vasculature of the cervical vertebrae including the vertebral artery and vein, which run in a cranial to caudal direction. 3 Pathological changes or failure of one of these joint constructs may negatively affect the IVF. 4 Osteochondrosis and osteoarthritis are the two primary disorders that affect the cervical articular processes in horses 4,5 and cervical APJ osteoarthritis is a relatively common problem in horses, particularly in the caudal cervical region.…”

“…12 The irritation in mild forms of APJ osteoarthritis might be treated with intra-articular or perineural steroid injection. [3][4][5][6][7][8][9][10][11][12][13][14][15] However, in severe APJ osteoarthritis accompanied by significant bony proliferation, mechanical compression may occur. In these cases, surgical intervention is the only approach to decompress the spinal canal or nerve roots.…”