Effect of Dexmedetomidine on Monitoring of Motor Evoked Potential in Anterior Cervical Surgery

Abstract：Objective To evaluate effect of dexmedetomidine for motor evoked potential monitoring during cervical spine surgery.Methods 90 patients undergoing single segment anterior cervical decompression were randomly assigned to a high-dose group,a low-dose group and a control group.The high-dose group was given a dosage of 1 μg/kg dexmede to midineat 10 minutes before the induction,while the low-dose group was given 0.5μg/kg dexmedetomidine and the control group received only the same dosage of saline injection.The amplitude and latency of motor evoked po-tential(MEP)was measured in three groups after drug administration,and the difference in amplitude and latency be-tween the three groups was compared.At the same time,the effective extraction rate of MEP after cervical decompres-sion was recorded and compared between the three group.Results The high dosage of dexmedetomidine significantly decreased the amplitude of MEP and prolonged the latency,with statistically significance when compared with the con-trol group.By contrast,the low dosage of dexmedetomidine had little influence on the amplitude and latency of MEP when compared with the control group.After the decompression of the cervical spine,the high dosage of dexmedetomi-dine resulted in the decrease of the effective extraction rate of ME while the low dose had little effect on the effective extraction rate of MEP.Conclusion Different dosage of dexmedetomidine will affect the MEP monitoring during spinal surgery.The high dosage causes the decreased of amplitude,the prolonged of latency and the decreased of effective ex-traction rate.Therefore,the dosage of dexmedetomidine should be maintained at 0.5~1.0 g/kg during anesthesia induc-tion,which will avoid the false-negative result of MEP and improve the accuracy of monitoring during surgery.