Anesthesia and intraoperative neurophysiological spinal cord monitoring

Purpose of review We will explain the basic principles of intraoperative neurophysiological monitoring (IONM) during spinal surgery. Thereafter we highlight the significant impact that general anesthesia can have on the efficacy of the IONM and provide an overview of the essential pharmacological and physiological factors that need to be optimized to enable IONM. Lastly, we stress the importance of teamwork between the anesthesiologist, the neurophysiologist, and the surgeon to improve clinical outcome after spinal surgery. Recent findings In recent years, the use of IONM has increased significantly. It has developed into a mature discipline, enabling neurosurgical procedures of ever-increasing complexity. It is thus of growing importance for the anesthesiologist to appreciate the interplay between IONM and anesthesia and to build up experience working in a team with the neurosurgeon and the neurophysiologist. Safety measures, cooperation, careful choice of drugs, titration of drugs, and maintenance of physiological homeostasis are essential for effective IONM

Comparing Motor-Evoked Potential Characteristics of NEedle versus suRFACE Recording Electrodes during Spinal Cord Monitoring—The NERFACE Study Part I

Muscle-recorded transcranial electrical stimulation motor-evoked potentials (mTc-MEPs) are used to assess the spinal cord integrity. They are commonly recorded with subcutaneous needle or surface electrodes, but the different characteristics of mTc-MEP signals recorded with the two types of electrodes have not been formally compared yet. In this study, mTc-MEPs were simultaneously recorded from the tibialis anterior (TA) muscles using surface and subcutaneous needle electrodes in 242 consecutive patients. Elicitability, motor thresholds, amplitude, area under the curve (AUC), signal-to-noise ratio (SNR), and the variability between mTc-MEP amplitudes were compared. Whereas amplitude and AUC were significantly higher in subcutaneous needle recordings (p 2 in more than 99.5% of the surface and subcutaneous needle recordings, and the variability between consecutive amplitudes was not significantly different between the two recording electrode types (p = 0.34). Surface electrodes appear to be a good alternative to needle electrodes for spinal cord monitoring. They are non-invasive, can record signals at similar threshold intensities, have adequately high SNRs, and record signals with equivalent variability. Whether surface electrodes are non-inferior to subcutaneous needle electrodes in detecting motor warnings is investigated in part II of the NERFACE study