Characteristics of spinal cord-evoked responses in man

The averaged electrical potentials evoked by the stimulation of the peripheral nerves were recorded with surface electrodes over the lumbosacral, lower thoracic and cervical spine and with epidurally placed electrodes in the cervical area. The waveforms of the lumbosacral and cervical spinal cord potentials show similar complexity reflecting peripheral and central generators. The larger negative wave with at least two components is followed by a slower positive deflection. Evoked potentials recorded over the cervical segments of the spinal cord with epidural electrodes are of much higher amplitude and more complex waveform than those recorded with surface electrodes.