Assessment of in vivo spinal cord conduction velocity in rats in an experimental model of ischemic spinal cord injury

Study design: Experimental laboratory investigation of spinal cord conductivity alterations in a rat model of ischemic spinal cord injury (SCI). Objective: To observe the epidural spinal cord stimulation-induced electromyography responses, and to investigate the possible alterations of spinal cord conduction velocity (SCCV) and compound muscle action potentials (CMAPs) after ischemic SCI in rats. Settings: Adnan Menderes University, Institute of Health Science, Aydin, Turkey. Methods: SCI was induced by transient occlusion of the abdominal aorta in male Sprague-Dawley rats. Spinal cord histopathology was examined to determine neuronal damage and Tarlov scale was used to grade locomotor functions. Epidural electrical stimulation of spinal cord was performed by monopolar needle electrodes sequentially at L1-L2 and L5-L6 levels, and CMAPs were recorded from the left gastrocnemius muscle by surface electrodes. Amplitudes and durations of CMAPs were evaluated and SCCVs were calculated by analyzing the latency difference of CMAPs. Results: Ischemia-induced SCI resulted in significant reduction of Tarlov scores and a significant decline in number of viable neurons. Similarly, a significant decrement was observed in SCCV following spinal cord ischemia. Conclusion: This study demonstrated that measurement of SCCV via epidural electrical stimulation is possible and displays a significant decline after spinal cord ischemia in rats. We suggest that this method can be beneficial to quantify neuronal damage after experimental ischemic SCI.