Analysis Of Postoperative Effects Of Vagus Nerve Stimulation In Patients With Refractory Epilepsy And Related Predictive Factors

ObjectiveTo evaluate the long-term treatment effect of vagus nerve stimulation(VNS)on patients with refractory epilepsy,and to predict the postoperative effect of VNS by statistical analysis and the changes of EEG before and after vagus nerve stimulation was started.MethodsFrom 2011 to 2019,in the Department of Functional Neurosurgery of Tianjin Medical University General Hospital,31 patients who met the DRE diagnostic criteria were selected.After perfecting the detailed medical history collection and comprehensive evaluation(long-term video EEG,head MR,PET-CT,etc.),the patient with no clear epilepsy focus,the focus was in the functional area,bilateral temporal lobe epilepsy,and no obvious surgical contraindication(arrhythmia,progressive neurological disease,mental illness and physical conditions are not suitable for surgery,etc.)underwent left VNS.After the general anesthesia during the operation,the scalp EEG test(the electrodes were placed according to the 20-10 system,and the placement positions were Fp1,Fp2,C3,C4,T3,T4,O1,O2)was performed on patients,and start the test during the operation.After the test,start the temporary stimulus.The stimulus parameters are(output power 1.0mA,signal frequency 30Hz,pulse width 500 μs,"start" 30s,"off" 5min).Analyze the changes of EEG(number of abnormal discharges,duration of synchronized discharges,background brain waves)before and after power-on stimulation.The post-operative program control was performed by a specialist.Follow-up was performed at 3 months,6 months,12 months,18 months,24 months,and 36 months.And dose),programmed parameters and adverse reactions.The effect of VNS was evaluated by McHugh effect classification.Results31 DRE patients with VNS are included in this study.Follow-up at 3 months,6 months,12 months,18 months,24 months,and 36 months,respectively.The average reduction rate of patients were 28.2%、44.9%、54.2%、55.8%、62.2%、62.7%,effective rate(McHugh Ⅰ,Ⅱ)were 29.0%(9/31),48.3%(14/29),59.2%(16/27),65.4(17/26),68%(17/25),66.7%(14/21).Studies have found that the effectiveness of VNS treatment continues to increase with prolonged stimulation.6 patients achieved seizure-free at the end of the follow-up.VNS treatment is better in younger(≤18 years)DRE patients than in older patients(>18 years)(P=0.024).However,there was no significant correlation between the patient’s gender,age of onset,and duration of disease and the effect of VNS treatment.Electroencephalogram a nalysis before and after intraoperative stimulation showed that there was no significant correlation between the effectiveness of VNS treatment a nd the improvement of background EEG(P=0.08),but patients with improved background EEG during surgery indicated to a certain extent that VNS had better treatment effect,and patients with a larger percentage reduction in abnormal EEG discharges have better efficacy after VNS(P=0.042).A total of 3 patients had adverse reactions after surgery.Two patients had hoarseness after irritation.One patient had fat liquefaction due to obese wounds and poor wound healing.Debridement and suture were given and the wound h ealed well.The characteristics of this study were to evaluate the changes in the EEG before and after the operation,and to find the factors related to the effectiveness of VNS.Conclusions VNS is effective and safe in the treatment of refractory epilepsy.With the prolonged stimulation time,the effectiveness of VNS treatment gradually increased.This study found that the effectiveness of VNS is related to the age of the patient,the percentage reduction in abnormal EEG discharges before and after temporary stimulation during the operation,and whether the background EEG changes.