Cervical vertebral canal endoscopy in the horse: intra- and post operative observations

Reasons for performing study: Despite modern medical diagnostic imaging, it is not possible to identify reliably the exact location of spinal cord compression in horses with cervical vertebral stenotic myelopathy (CVSM). Vertebral canal endoscopy has been successfully used in man and a technique for cervical vertebral canal endoscopy (CVCE) has been described in equine cadavers. Objective: To determine the feasibility and safety of CVCE in healthy mature horses. Methods: Six healthy mature horses were anaesthetised. A flexible videoendoscope was subsequently introduced via the atlanto‐occipital space into the epidural space (epiduroscopy, Horses 1–3) or the subarachnoid space (myeloscopy, Horses 4–6) and advanced to the 8th cervical nerve. Neurological examinations were performed after surgery and lumbosacral cerebrospinal fluid (CSF) analysed in horses that had undergone myeloscopy. Results: All procedures were completed successfully and all horses recovered from anaesthesia. Anatomical structures in the epidural space (including the dura mater, nerve roots, fat and blood vessels) and subarachnoid space (including the spinal cord, blood vessels, arachnoid trabeculations, nerve roots and the external branch of the accessory nerve) were identified. During epiduroscopy, a significant increase in mean arterial pressure was recognised, when repeated injections of electrolyte solution into the epidural space were performed. In one horse of the myeloscopy group, subarachnoid haemorrhage and air occurred, resulting in transient post operative ataxia and muscle fasciculations. No complications during or after myeloscopy were observed in the other horses. CSF analysis indicated mild inflammation on Day 7 with values approaching normal 21 days after surgery. Conclusions: Endoscopic examination of the epidural and subarachnoid space from the atlanto‐occipital space to the 8th cervical nerve is possible and can be safely performed in healthy horses. Potential relevance: Cervical vertebral canal endoscopy might allow accurate identification of the compression site in horses with CVSM and aid diagnosis of other lesions within the cervical vertebral canal.