Amplitude and latency characteristics of spinal cord motor-evoked potentials in dogs.

The motor-evoked potential can be reliably recorded in anesthetized dogs by use of percutaneous placement of active recording electrodes near the dorsal lamina of the vertebral column. Two types of responses were observed in this study; short (less than 5.5 ms at T9-10)- and long (greater than 5.8 ms at T9-10)-latency waves. Short-latency waves are larger in amplitude and appear with higher stimulus intensities than do long-latency waves. Short-latency waves are conducted at greater than 80 m/s and may not reflect pyramidal tract activation. The safety of using higher intensity stimuli to generate short-latency waves has not been determined.