Spinal cord and nerve root monitoring in spine surgery and related procedures

Intensive research in the field of intraoperative neurophysiologic monitoring has been performed directed at finding reliable stimulating and recording techniques and adequate anesthetic regimes applicable to spinal procedures. The aim is a comprehensive monitoring not only of afferent and efferent spinal cord pathways but also of sensory and motor nerve roots and cauda equina fibers. Conventional somatosensory evoked potentials (SEPs) are complemented by motor evoked potentials, dermatomal sensory evoked potentials, spinal cord evoked potentials, evoked electromyography, sensory and motor fiber mapping of the cauda equina, bulbocavernosus reflex testing, and neurogenic evoked potentials. Apart from describing the essentials of these techniques and their indications and limitations, this article deals with the influence of anesthetic management on the production and interpretation of evoked potentials.