The Availability of Total Intravenous Anesthesia on Somato-Sensory Evoked Potential during Spinal Surgery

Lee, Sang Seock; Lym, Yun Hee; Youn, Jun Hum; Kim, Joung Won; Hong, Ki Hyouk

Abstract

BACKGROUND: Somatosensory evoked potential (SSEP) has been used to help minimize neurologic morbidity during spinal surgery. But, SSEP is affected by various factors, namely technical errors, anesthetics and physiologic aspects (systemic blood pressure, temperature, blood gas tensions). We experienced 40 cases of spinal surgery done with total intravenous anesthesia under SSEP monitoring. We reviewed these cases with the availability of total intravenous anesthesia during SSEP monitoring.
METHODS
Forty patients, ASA class I-II, free of neurologic disease and scheduled for elective spinal surgery were randomly selected for the study. All of the operations were performed under general anesthesia employing the method of total intravenous anesthesia with propofol and fentanyl, and monitored by SSEP. We recorded latency and amplitude of SSEP in the pre-induction, post-induction, during-instrument insertion and post-distraction periods.
RESULTS
There were no statistical differences in latencies among pre-induction, post-induction, screw insertion and post-distraction period. The amplitude of the post-induction period was statistically higher than pre-induction period (p<0.05), but there were no differences in other periods. None of cases showed abnormal findings (i.e., delay of latency over 10% or decrease of amplitude over 50%).
CONCLUSIONS
SSEP monitoring may be helpful in identifying potentially neurologically threatening surgical maneuvers during spinal surgery. To achieve better outcomes, we should consider the effects of various factors on SSEP. Total intravenous anesthesia may be useful method, which has lifter influence on SSEP monitoring.