First experience of intraoperative nerve root monitoring with the INS-1-device on the lumbosacral spine

Abstract

The goal of intraoperative nerve root monitoring on the lumbosacral spine is to minimize the risk of nerve root injuries during surgery by reducing the incidence of misplaced pedicle screws. In this study we hypothesized that the INS-1 device (Nuvasive) may provide more accurate information about screw placement. The INS-1 device provides a means for intraoperative EMG stimulation through the inside of the pedicles or the implanted screws. The readings from relevant muscles serve as a monitoring technique to detect perforated pedicles and thus can be used to prevent or detect misplaced pedicle screws and reduce the risk of nerve root injuries. We controlled 58 patients with 334 implanted pedicle screws. Our first experience with 334 pedicle screws shows that nerve root injuries can be avoided by reducing the number of misplaced pedicle screws through additional intraoperative information gained by the INS-1 device. Thus we corrected 3.9 % of screws intraoperatively in cases without relevant information from fluoroscopic control. The INS-1 device is a helpful tool to obtain additional information on misplaced pedicle drill holes or already implanted screws in the lumbosacral spine.