Thoracic Evoked Spinal Cord Potential by Stimulation of the Intercostal Nerve

We attempted to record the thoracic evoked spinal cord potential by stimulation of intercostal nerve in cats to level diagnosis and evaluation of spinal cord function.The recording electrode was applied in the dorsal epidural space and the reference electrode was placed in the paravertebral muscles.The basic waveform consisted of two major components; a triphasic spike and negative wave, named P1, P2, N1 and N2, in order of their polarities and latencies.The latency of N1 progressively increased at the more cranial recording sites and the N1 response diminished cranially with sectioning of the spinal cord. The amplitude of N2 was decreased by high frequency stimulation, and was considered post-synaptic potential.We confirmed that thoracic evoked spinal cord potential stimulation of the intercostal nerve is useful to level diagnosis from experimental study of acute spinal cord compression.