Neurophysiological tests that asses afferent or efferent pathways of the spinal cord and of nerve roots are used for clinical diagnosis, intraoperative monitoring, and judgement of prognosis. Most tests can readily be performed in awake subjects, whereas many difficulties arise in anesthetized patients in whom neurophysiological testing is the only way of monitoring functional integrity of neural tissue. The research, therefore, that has been carried out in this field during the past year is of special interest.