Variability of somatosensory cortical evoked potentials during spinal surgery. Effects of anesthetic technique and high-pass digital filtering

• Published in: Spine (Philadelphia, Pa. 1976) Vol. 16; no. 8; p. 924
• Main Authors: Kalkman, C J, ten Brink, S A, Been, H D, Bovill, J G
• Format: Journal Article
• Language: English
• Published: United States 01.08.1991
• Subjects: Adult; Alfentanil; Anesthesia, General - methods; Evoked Potentials, Somatosensory - physiology; Female; Humans; Male; Monitoring, Intraoperative - methods; Nitrous Oxide; Propofol; Signal Processing, Computer-Assisted; Spine - surgery; Tibial Nerve - physiology
• ISSN: 0362-2436
• DOI: 10.1097/00007632-199108000-00010

The effects of anesthetic technique (nitrous oxide or propofol) and high-pass digital filtering on within-patient variability of posterior tibial nerve somatosensory cortical evoked potentials (PTN-SCEP) were compared prospectively in two groups of 20 patients undergoing spinal surgery. Average P1N1 amplitude was significantly higher and P1N1 amplitude variability lower during propofol/alfentanil anesthesia than during nitrous oxide/alfentanil anesthesia. Off-line 30-Hz high-pass digital filtering significantly reduced P1N1 amplitude variability without decreasing P1N1 amplitude. In 93 patients studied retrospectively, a significant negative logarithmic correlation (r = -0.77) was observed between P1N1 amplitude and P1N1 amplitude variability. This study shows the importance of maintaining the highest possible PTN-SCEP amplitudes during spinal surgery. Propofol/opioid anesthesia may be an alternative anesthetic technique to nitrous oxide/opioid anesthesia during spinal cord function monitoring.