Effects Of Dexmedetomidine On Somatosensory And Motor-evoked Potential During Cervical Spine Surgery With Intravenous Anesthesia

Objective The study intends to observe the effects of dexmedetomidine on somatosensory and motor evoked potential during cervical spine surgery with total intravenous anesthesia,and to provide clinical reference.Methods A series of forty five patients were enrolled who had undergone cervical spine surgery in General Hospital of Ningxia Medical University,and randomly divided into two groups named group D（dexmedetomidine group,n=23）and group C（control group,n=22）.Dexmedetomidine infusion was started at1ug/kg for 10 minutes before induction in Group D,then maintained at 0.4ug/kg.h during the operation.The same dose of saline were injected in Group C.Evoked responses were evaluated under seven conditions:awaking（T₀）,at the end of the loading dose infusion（T₁）,when consciousness disappears after induction of anesthesia（T₂）,immediately after intubation（T₃）,immediately after positioning（T₄）,spinal canal decompression（T₅）,and interbody fusion cage insertion（T₆）.The amplitude（N13-P15、N45-P37）and latency（N13、P15、N45、P37）of SEP,heart rate（HR）,mean arterial pressure（MAP）,body temperature（T）,and bispectral index（BIS）values were recorded at these seven time points;recording the red blood cell specific volume（HCT）before and after the operation,and the dosage of propofol and remifentanil during intraoperative period of the two groups;comparing the number of MEP elicitation of the two groups;recording the adverse reactions such as bradycardia,tachycardia,intraoperative hypotension and intraoperative hypertension;the scores of the Japanese Orthopaedic Association（JOA score）were compared between the two groups before and on the seventh day after surgery.Results A total of 40 patients completed the study.1.Compared with T₀,the N13-P15 amplitude decreased at T₁and T₆in group D（P<0.05）,and the N13-P15amplitude decreased significantly at T₆in group C（P<0.01）;the amplitude of N45-P37 decreased at T₁,T₅,and T₆in group D（P<0.05）,and decreased significantly at T₅and T₆in group C（P<0.01）;there were no significance at other time points in two groups（P>0.05）.The comparison of N13-P15 amplitude was not statistically significant between the two groups（P>0.05）;compared with group D,the N45-P37 amplitude of group C decreased significantly at T₄（P<0.05）;there was no significance in other time points between the two groups（P>0.05）.2.Compared with T₀,the N13,P15,N45,and P37 latency were not statistically significant of the two groups（P>0.05）,and the comparison was no significance as well between the two groups（P>0.05）.3.There was no statistical difference on the MAP,HR,T,and BIS between the two groups（P>0.05）.4.There was no significance on HCT counts before and after the surgery（P>0.05）,and the dosage of propofol and remifentanil was also no significance during the intraoperation between the two groups（P>0.05）.5.There were no significant differences on MEP elicitation,bradycardia,tachycardia,intraoperative hypotension,intraoperative hypertension between the two groups（P>0.05）.6.There was no difference about JOA score between the two groups（P>0.05）.Conclusion Dexmedetomidine has no significant effect on the amplitude,latency of SEP,and has no effect on introduction of MEP during cervical spine surgery.So,it can be used safely for this type of surgery.