Existing work indicates that the degree of variation of somatosensory evoked potential (SEP) signals between a healthy spinal pathway and spinal pathway affected by spinal cord injury (SCI) can be used to evaluate the integrity of the spinal pathway. This paper develops a metric that exploits the time-domain features of SEP signals (relative amplitude, time scaling, and time duration) in order to quantify the level of SCI. The proposed method is tested on actual SEP signals collected from rodents afflicted with focal demyelination SCI. Results indicate that the proposed method provides a robust assessment of the different degrees of demyelination in the spinal cord.