Changes of the Electrophysiological Study in Dogs with Acute Spinal Cord Injury

OBJECTIVE: This study describes a method for inducing spinal cord injuries in dogs by using balloon catheters via laminectomy and the subsequent changes in the electrophysiological response. METHODS: Female Beagle (Orient Bio, Seongnam, Korea) dogs weighing 10 kg at the time of injury were used. Under inhalation anesthesia, a posterior midline approach laminectomy was performed. A silicone balloon catheter (size 6 Fr; Sewoon Medical, Cheonan, Korea) was then inserted into the vertebral canal at the center of T10. The balloon was inflated to the maximum volume for 1, 2, or 3 days. Open field testing was performed for evaluating motor functions of the hindlimbs. Motor evoked potentials (MEPs) induced by electrical and magnetic stimulation were recorded before and after spinal cord injury. RESULTS: Open field testing yielded locomotor scores of 0 or 1 for dogs subjected to compression for 3 days. These dogs showed no obvious improvement throughout the observation period, and the tonus of their hindlimbs was flaccid. In contrast, motor functions of dogs that had experienced compression for 1 or 2 days were variable, and all dogs showed spastic tonus in their hindlimbs. In dogs subjected to after compression for 3 days, electrically stimulated MEPs for the hindlimbs showed a significant amplitude reduction. Further, hindlimb movements were not evoked by magnetic stimulation of the cervical spine and vertex area. CONCLUSION: Compression for 3 days with a balloon catheter is a safe, reproducible, and reliable method for evaluating electrophysiological changes in a dog model of complete spinal cord injury.