Evoked potential versus behavior to detect minor insult to the spinal cord in a rat model

Reliable outcome measurement is needed for spinal cord injury research to critically evaluate the severity of injury and recovery thereafter. However, such measurements can sometimes be affected by minor, injury to the spinal cord during surgical procedures, including laminectomy. The open-field Basso, Beattie and Bresnahan (BBB) behavior motor scores are subjective and prone to human error. We investigated somatosensory evoked potential (SEP) as an electrophysiological measure to assess the integrity of the spinal cord after injury. In our experiment, control rats with a minor unintentional spinal cord insult during laminectomy showed a decrease in SEP amplitude by 16% to 18%, which recovered in around 7 days. However, there was no change in the BBB scores for the same animals over the same period. This highlights the sensitivity of SEP to minor insult as compared to BBB. These differences may be beneficial in accurate evaluation of the severity and progression of spinal cord injury, and subsequent recovery.