Intraoperative neurophysiological monitoring in spinal surgery requires a multimodal approach in order to assess the integrity of ascending, descending tracts and of nerve roots. To this end, it is recommended to continuously record during surgery, the motor and sensory evoked potentials (MEPs, SEPs), as well as the electromyographic (EMG) activity. Sensory evoked potentials are obtained by peripheral stimulation of nerves and recording at scalp level. Motor evoked potentials are obtained by transcranial or cortical electrical stimulation recorded at selected muscles level, from where spontaneous electromyographic routes are also obtained.