Somatosensory- and Motor-Evoked Potentials in Surgery of Eloquent Cortex Under General Anesthesia: Advantages and Limitations

In this chapter we will discuss two neurophysiological tools: somatosensory-evoked potentials (scalp and cortically recorded) and motor-evoked potentials (transcranial stimulation, direct cortical stimulation, and direct subcortical white matter stimulation), which assist the neurological surgeon operating under general anesthesia upon a patient with a cerebral lesion in proximity to eloquent cortex. We define eloquent cortex as a region whose damage may likely result in a neurological deficit within the realm of motor (paralysis, weakness, coordination), or sensory discrimination (perceptual, visual, spatial orientation, agnosia, apraxia).