Spinal evoked potentials from the motor tracts.

There is a need to monitor the motor system, but it has a different blood supply and a different location in the spinal cord from those measured by traditional somatosensory evoked potential monitoring. This paper reports a motor evoked potential monitoring system that uses direct spinal cord stimulation overlying the areas of the motor tract in the cord. In nine cats, evoked potentials were recorded from the dura, which gave a much faster main signal component than the traditional dorsal column evoked potentials, which were also recorded. This 100-m/sec signal was not affected by sectioning of the dorsal columns, which was verified histologically. This mode of monitoring the motor system can be used during surgery. It may also provide a better evaluation of patients after spinal cord trauma.