Objective: This study documents the monitorability using different anesthesia regimes and accuracy of muscle motor evoked potentials (mMEPs) in children ≤2 years of age undergoing tethered cord surgery (TCS).
Methods: Intraoperative mMEP monitoring was attempted in 100 consecutive children, ≤2 years of age, undergoing TCS. MEP monitoring was done under 4 different anesthetic regimes: (Total intravenous anesthesia (TIVA); balanced anesthesia with sevoflurane and ketamine; balanced anesthesia with isoflurane and ketamine; and balanced anesthesia with sevoflurane). Factors analyzed for their effect on monitorability were: age, neurological deficits, type of anesthesia, and the number of pulses used for stimulation.
Results: Baseline mMEPs were obtained in 87% children. Monitorability of mMEPs was similar in children ≤1 year and 1-2 years of age (85.7% and 87.5%). In multivariate analysis, anesthesia regime was the only significant factor predicting presence of baseline mMEPs. Children undergoing TIVA (p=0.02) or balanced anesthesia with a combination of propofol, sevoflurane, and ketamine (p=0.05) were most likely to have baseline mMEPs. mMEPs had a sensitivity of 97.4%, specificity of 96.4%, negative predictive value of 98.2% and accuracy of 96.8%.
Conclusions: Baseline mMEPs were obtained in >85% of children ≤2 years of age including those who had motor deficits. TIVA and balanced anesthesia with sevoflurane and ketamine are ideal for mMEP monitoring. mMEPs have a high accuracy although, false positive and false negative results can occasionally be experienced.
Keywords: Children; Intra-operative monitoring; Motor evoked potentials; Tethered cord surgery.