DEVELOPMENT OF A PERINEURAL INJECTION OF THE CAUDAL CERVICAL SPINAL NERVE ROOTS IN HORSES

Abstract

Neck pain in horses can result in lameness and poor performance and can occur from arthritis of cervical articular process joints (APJs). Current treatment consists of direct injection of corticosteroids into the cervical APJs; however, this does not alleviate pain in all horses. New bone formation around the APJ can also result in compression of the spinal nerve roots and pain. The purpose of this study was to develop an ultrasound-guided cervical perineural injection technique and assess the safety of performing the technique in normal healthy horses. An ultrasound-guided cervical perineural injection technique of the caudal cervical spinal nerve roots (CSNR 5–7) was developed in cadaveric necks of horses. Paramagnetic or iodinated contrast was injected and the distribution was evaluated using magnetic resonance (MR) or computed tomography (CT) imaging, respectively. The ability of the perineural injection technique to distribute contrast agent to the CSNR region was compared with intra-articular and periarticular injection techniques. In a second study, the safety of the ultrasound-guided perineural injection technique was evaluated in normal, healthy horses. Pain and swelling at the injection site, along with lameness, was evaluated before and after injection and compared to intra-articular injection of the cervical APJs. Perineural injections delivered contrast agent to the CSNR region 100% of the time, which was significantly greater than the ability of the intra- articular injection to deliver contrast to the CSNR region (p = 0.008). In the second study, the perineural injection techniques were found to be safe with no difference noted in pain, swelling or lameness compared to horses receiving intra-articular injection of the cervical APJs. Overall, the ultrasound-guided perineural injection technique developed in this study successfully delivered contrast agent to the CSNR region and was found to be safe. This technique could potentially be used for the diagnosis and treatment of cervical pain in horses, particularly in cases where intra-articular injection of the cervical APJ was not beneficial. Further studies are necessary to assess the effectiveness of the ultrasound-guided perineural injection technique in clinical horses suffering from neck pain due to impingement of the cervical spinal nerve roots.