Objective To study the effect of vagus nerve stimulation (VNS) on the expression of multidrug resistance-associated protein (MRP1) in brains of rats with drug refractory epilepsy.Methods Rat models based on the lithium-pilocarpine epileptic rats were induced with sodium phenobarbital (PB).Then,the rats were randomly divided into three groups:VNS group (n=7),sham-VNS group (n=6) and control group (n=6); VNS through stimulation device was given to the rats in the VNS group,stimulation device without VNS was given to the rats in the sham-VNS group,and rats in the control group were only given conventional feeding.Behavioral changes and number of seizures were recorded by continuous video monitoring during the whole process.And the amount of MRP1 over-expression in each group was detected following a four-week VNS.Results (1) The seizure frequency in VNS group (2.6±1.0 per week) was significantly decreased as compared with that in sham-VNS group (5.3±1.1 per week) or control group (5.2±1.3 per week) after a four-week VNS (P＜0.05).(2) The MRP1 expression in VNS group had significantly statistical differences as compared with that in the sham-VNS group and control group (the absorbance values:9120±1496,19556±1462 and 20231±1710,P＜0.05).Conclusion VNS can effectively decrease the seizures frequency through reducing the MRP1 over-expression.

Objective To study the acute effect of vagus nerve stimulation (VNS) on status epilepticus (SE) in rats.Methods Forty-eight male Wistar rats were randomly divided into 4 groups:Group A (VNS preconditioning group),accepted VNS at 2 h before pilocarpine injection,Group B (VNS treatment group),accepted VNS immediately after pilocarpine injection,Group C (negative control group),implanted with electrode without stimulation,and Group D (SE model group),without electrode implantation (n=1 2).Lithium-pilocarpine was used to kindle the rats to establish SE models.Stimulation parameters used in the procedure of VNS were as follows:frequency,30 Hz; pulse width,0.5 ms; current,1 mA; and duty cycle,on-30 s,off-30 s.Behavior changes were observed and caspase-3 expression in dentate gyrus was detected 72 h after pilocarpine injection.Results (1) The seizure frequencies of grade Ⅳ and Ⅴ (Racine grading) in group A and B were significantly fewer than those in group C and D (P＜0.05); the seizure frequency of grade Ⅴ in group A was significantly fewer than that of group B (P＜0.05); SE latency in group A was significantly longer than that in other groups (P＜0.05).(2) Expressions of caspase-3 in the dentate gyrus of group A and B were significantly lower than those of group C and D (absorbancy values being 5854.7±856.5,6244.8±806.0,11957.0±1948.1 and 11543.2±1734.7,P＜0.05).Conclusion VNS has an acute seizure-suppressing effect on SE in rats and it can also reduce neuronal apoptosis induced by SE in hipocampus.

Objective To summarize the common causes and types of circuit failure after vagus nerve stimulator (VNS) implantation,and analyze the available methods of resolving these problems.Methods Three patients with postoperative circuit fault in the 97 patients performed VNS implantation for drug refractory epilepsy in our hospital from October 2011 to January 2014,and three patients with postoperative circuit fault performed surgery in other hospitals at the same period were chosen in this study.The causes of circuit failure of these 6 patients were identified by performing system diagnostics and X-ray evaluation.A revision surgery may be necessary if a broken or damaged lead was suspected.Results In these 6 patients of device failure,two patients were due to the disconnection of the lead from the pulse generator;the lead impedance became normal after re-inserting the existing lead connector pins into the pulse generator following proper lead insertion techniques.Four patients performed lead revision surgery to replace or remove the existing lead;in 3 of them,the helices and associated scar tissues were removed from the vagus nerve under the microscope,and a new set of electrodes was placed;in one of them,the lead was transected as much as possible and the distal portion of the lead was severed at the neck following the removal of pulse generator.There were no complications such as hoarse voice,dyspnea,slow rhythm,subcutaneous hematoma or infection after the revision surgery.Five patients were followed up,indicating the devices work normally.Four patients had obvious improvement,and one patient had no significant improvement after the revision surgery.Conclusions The high lead impedance is the main manifestation of circuit failure after vagus nerve stimulator implantation.Surgical exploration is an effective method to identify and resolve these problems.

Objective To explore the insula sensory features and analyze its electrophysiological characteristics based on stereo-electroencephalograph (SEEG).Methods The clinical data of 16 drug-refractory epilepsy patients,admitted to our hospital from December 2013 to June 2016,were retrospectively analyzed.All patients were implanted with SEEG electrodes;totally,34 electrodes (257 contacts) located in insular lobe.Micro current stimulation was performed every adjacent two contacts to get the sensory mapping and the stimulus threshold of the insula.Results Of all the 257 contacts,160 presented clinical symptoms (positive contacts);there were 149 contacts with sensory manifestations,of which 72 were on the left side and 77 on the right.Sensory symptoms of insula mainly included both somatic sensation and visceral sensation.The threshold of somatosensory was (4.9±2.9) mA,and the threshold of visceral sensation was (6.0±2.9) mA,without significant difference (P＞0.05).No significant difference was noted between the left insula sensory ([6.2±3.1] mA) and the right insula sensory ([5.7±2.8] mA,P＞0.05).It showed sensation abnormal of larynx,lingua,face and limb when the middle and posterior short gyrus,as well as anterior and posterior long gurus,respectively,were stimulated;insula sensory showed anatomy distribution,with different stimulated sensitivities.The sensory function showed parallel distribution with the insular gyrus from the middle short gyrus to posterior long gurus,as laryngeal-lingual-facial (nasal and lips)-limb sensation,and the thresholds of the five insular gurus were (6.0±3.1) mA,(4.7±1.5) mA,(8.0±2.9) mA,(5.1±2.4) mA and (4.5±2.6) mA,respectively,with statistically significant differences (P＜0.05).Conclusions The sensitivity of somatic sensation and visceral sensation of the insula monitored by SEEG is similar,as well as the left and right side.The sensory threshold and sensory fan-shaped distribution play important roles in conforming insular symptoms and location for clinician.

Objective To investigate the extents of corpus callosotomy (CC) resulting in optimal seizure control and compare the efficacies and complications of two CC approaches. Methods Clinical data of 25 patients underwent CC in our hospital from January 2013 to December 2018 were retrospectively analyzed. All 25 patients were diagnosed as having medically refractory epilepsy, and 27 CC procedures were performed. The patients underwent either anterior two thirds CC (n=13) or single-stage complete CC (n=12). Two patients had a second-stage posterior CC in 61 and 36 months after anterior CC, respectively. The efficacies were studied by using two evaluation indexes, the effective rate (worthwhile improvements) and the markedly effective rate (favorable outcomes).Results The average postoperative follow-up time was 2.6 years. In comparison, the markedly effective rate (>75％ reduction in seizure frequency or severity) was 71.4％ after complete CC and 15.4％ after anterior two thirds CC with a statistical significant difference between the two groups (P<0.05). The effective rate (>50％ reduction in seizure frequency or severity) of complete CC (78.6％) was higher than that of anterior two thirds CC (53.8％), but without significant difference (P>0.05). Overall, 66.7％ of patients benefited from anterior or complete CC. There were no such complications as intracranial hemorrhage, hydrocephalus, cerebrospinal fluid leakage or postoperative infection.Conclusion Complete CC is more effective for seizure control than anterior two thirds CC; no permanent neurological deficits are observed postoperatively.