Intraoperative monitoring of motor evoked potentials in very young children.

Object: Neurophysiological monitoring of motor evoked potentials (MEPs) during complex spine procedures may reduce the risk of injury by providing feedback to the operating surgeon. While this tool is a well-established surgical adjunct in adults, clinical data in children are sparse. The purpose of this study was to determine the reliability and safety of MEP monitoring in a group of children younger than 3 years of age undergoing neurosurgical spine procedures.

Methods: A total of 10 consecutive spinal procedures in 10 children younger than 3 years of age (range 5-31 months, mean 16.8 months) were analyzed between January 1, 2008, and May 1, 2010. Motor evoked potentials were elicited by transcranial electric stimulation. A standardized anesthesia protocol for monitoring consisted of a titrated propofol drip combined with bolus dosing of fentanyl or sufentanil.

Results: Motor evoked potentials were documented at the beginning and end of the procedure in all 10 patients. A mean baseline stimulation threshold of 533 ± 124 V (range 321-746 V) was used. Six patients maintained MEP signals ≥ 50% of baseline amplitude throughout the surgery. There was a greater than 50% decrease in intraoperative MEP amplitude in at least 1 extremity in 4 patients. Two of these patients returned to baseline status by the end of the case. Two patients had a persistent decrement or variability in MEP signals at the end of the procedure; this correlated with postoperative weakness. There were no complications related to the technique of monitoring MEPs.

Conclusions: A transcranial electric stimulation protocol monitoring corticospinal motor pathways during neurosurgical procedures in children younger than 3 years of age was reliably and safely implemented. A persistent intraoperative decrease of greater than 50% in this small series of 10 pediatric patients younger than 3 years of age predicted a postoperative neurological deficit. The authors advocate routine monitoring of MEPs in this pediatric age group undergoing neurosurgical spine procedures.