Graded risk levels of somatosensory evoked potentials during scoliosis surgery

Abstract

It is essential to monitor spinal cord integrity throughout spinal surgery, particularly during spinal manipulation and instrumentation. However, because the procedures are carried out under general anaesthesia, the neurological status cannot be tested until the patient awakens after surgery. The application of intraoperative somatosensory evoked potential (SEP) monitoring makes it possible to assess the integrity of the peripheral nerve, spinal cord, and central neuronal pathway. Clearly, the total disappearance of the SEP is an unequivocal alarm signal, but it would be helpful to have a value that would constitute a warning before complete disappearance. Therefore, we followed a series of patients undergoing surgery with instrumentation for correction of scoliosis and developed risk levels by measuring SEP at different times during surgery. In this paper we provide information that will facilitate earlier awareness and timely detection of SEP deterioration to prevent catastrophic spinal cord injury.