The Assessment For The Effectiveness And Curative Effect Of MEP Combined EMG Monitoring During Lumbar Spinal Stenosis Surgery

Objective By observing the monitoring result of MEP combined EMG monitoring during the operation for patients with lumbar spinal stenosis,the complications and the curative effect postoperatively,to discuss whether the MEP combined EMG monitoring is effective to MIS-TLIF and whether monitoring indexes have the ability of asses the curative effect.Materials and Methods We prospectively evaluated 64 patients(30 males and 34 females)who had undergone minimally invasive surgery transforaminal lumbar interbody fusion for lumbar spinal stenosis at the First Affiliated Hospital of Hainan Medical College between October 2015 and April 2016.All patients underwent intraoperative neurological monitoring.The MEP and EMG responses were elicited by transcranial electrical stimulation using a NIM-EC LIPSE E4 system(Medtronic,America).We are performing the continued implementation of monitoring from the exposed spine to t he closure of the incision.The monitoring criteria is that a positive monitoring outcome is adopted if one of six recordings has more than an 80% decrease in amplitude,with or without burst EMG activity.Postoperatively all patients had regular follow-up examinations at 1-month,3-month,6-month and 12-month intervals.The clinical effect and pain was assessed using JOA score.the VAS score for low back pain,leg pain and numbness at 3 and 12 months postoperatively.At the same time we rank the clinical outcome according to the ameliorative rate of symptom for the JOA score.To determine significant differences,the statistical comparison between the preoperative and postoperative JOA scores and VAS scores was performed using the unpaired t-test.The correlation between parameters including JO A scores,VAS scores and relevant MEP index were analyzed using Spearman Rank Correlation.The level of significance was set at p<0.05 was evaluated.Result(1)During 64 surgical treatment for lumbar spinal stenosis with MEP and EMG monitoring,the false positive rate was 24.6%,the false negative rate was 0.The sensitivity of MEP combined EMG monitoring was 100 %,however,the specificity 75.4%.the positive predictive value and the negative predictive value were 16.7%and 100% respectively.(2)Nonsignificant intraoperative MEP changes were found in 44 patients.All of them have a great clinical effect and no motor deficit postoperatively.Significant intraoperative MEP changes were found in 20 patients(31.3%).In 18 of them,significant MEP changes were synchronously and logically associated with high-risk surgical maneuver.Three patients had nerve deficit postoperatively.Among them,one patient had right nerve root deficit and planter numb.another was found with muscle weakness of the right foot dorsiflexion postoperatively,returning to the level 5 at the last follow-up.The worst one of them showed low back pain,leg pain and numbness were getting worse than the preoperative one year later.The patient had Motor disturbance after that.(3)In postoperative 3 months,31 cases showed that the recovery rate of JOA score was more than 60%,32 cases showed that the recovery rate of JOA score ranged from 25% to 60%,1 case showed that the recovery rate was less than 25%.The effect is significant at 48.43%.In postoperative 1 year,59 cases showed that the recovery rate was more than 60%,4 cases showed that the recovery rate ranged from 25% to 60%,1 case was ineffective.The significant effect is 92.18%.The number of the significant clinical effect case increased from a postoperative 3 months value to a postoperative 12 months value(X~2 =29.342,p < 0.001).During postoperative 3 months and 1 year,JOA score,the VAS score for low back pain,leg pain and numbness were significantly improved compared with those preoperatively.The difference was statistically significant(P <0.001).(4)The preoperative MEP latency was related to the preoperative VAS score for leg pain and numbness(p<0.05).The number of the channel with more than 50% improvement in amplitude postoperatively and the improvement in MEP amplitude postoperatively were related to the preoperative motor disturbance(p<0.05).The improvement in MEP amplitude was related to sensory disturbance(p<0.05).In postoperative 3 months and 1 year,postoperative MEP latency,postoperative number of channel and the improvement in MEP amplitude postoperatively,partly or completely affected subjective,symptoms and objectivity clinical signs involving motor disturbance,sensory disturbance,the Vas score for leg pain and numbness and the Vas score for low back pain.(p<0.05).The number of channel and the improvement in MEP amplitude postoperatively significantly increased in patients whose recovery rate of JOA score was more than 60% in post-op.3 or 12 months(p<0.05).We did not find any significant difference in pre-op.or post-op.MEP latency in relation to JOA score.(p>0.05)Conclusion(1)MEP combined EMG monitoring is more sensitive than using one of them.We didn’t find any false negative undergo this monitoring.It is claimed that combing MEP with EMG as a monitoring method is reliable for lumbar spinal stenosis surgery using the criteria that if one of six recordings had more than an 80% decrease in amplitude,with or without burst EMG activity,that positive monitoring outcome is adopted.(2)There was a correlation between the changes of MEP and the postoperative clinical effect.Therefore we have reason to believe that the clinical effect and postoperative neurological status can be accessed through muliti-intraoperative neurophysiological monitoring combined with relevant MEP indication as alert.