Initial Study Of Electrical Impedance Tomography In The Epileptic Rats Induced With Ferric Chloride

Epilepsy is a chronic disorder of the nervous system of the brain caused byrepeated brain cells irregular discharge diseases caused due to a variety of reasons.According to the statistical analysis of the global epidemiology, at least50,000,000of epilepsy patients in the world, and our country has at least9,000,000people withepilepsy. There are70%patients can get good control epilepsy by using theantiepileptic drugs,but there are30%people because of taking the drug ineffective,ultimately become refractory epileptic patients. Refractory epilepsy due to repeatedseizures, the patient’s quality of life was significantly decreased, and give thepatients themselves and their family ’s health has brought the huge influence. Atpresent, operation treatment is still the most effective treatment of refractoryepilepsy. But for epilepsy operation, epilepsy preoperative assessment (i.e.: how toaccurately determine the epileptic foci) is the key to the success of the operation. In1929, Berger invented the EEG, this is the first time for epilepsy diagnosis andqualitative description of the diagnostic monitoring. Nineteen eighties, By uesingthe video EEG that link the epilepsy clinical seizure phenomena and paroxysmalEEG changes, and CT (Computed Tomography), MRI (Magnetic Resonance Imaging) and PET (Possitron Emission Tomography) and some other complexneuroimaging techniques to make the epilepsy preoperative assessment level withthe further development. However, there are still a part of patients with refractoryepilepsy due to the imaging and video EEG is not found clear epileptic foci havestill suffering epilepsy patients. How to accurately find the epileptic foci by usingsome effective means is a very problem that restrict our epilepsy surgerydevelopment. Previous studies think that, the function of brain activity andpathological changes can both cause the bioelectrical impedance changes, thisresults can allow us to use the electrical impedance imaging technology in thepreoperative evaluation of epilepsy, at the same time,Compaire with the X raycomputed tomography (CT) and nuclear magnetic resonance (MRI),the electricalimpedance imaging technique have a lot of incomparable advantages, For example,noninvasive, real-time and harmless. Whether the electrical impedance tomographyis applied to epilepsy in the preoperative evaluation of the objectives of our study.The purpose of this experiment is to study the imaging law of the electricalimpedance tomography system for the detection of epileptic seizure rats as well asthe EEG and electrical impedance tomography system synchronous detection, andlay a theoretical basis for the future clinical application of EIT in the preoperativeevaluation of epilepsy.10rats in Experiment one in and5rats in Experiment twoare given1%pentobarbital intraperitoneal anesthesia (55mg/kg) fixed in astereotaxic instrument, along the midline cut begin skin and soft tissue afterexposed to both sides of the skull, to clean the surface of the skull to be dry with abackup by using hydrogen peroxide. After the success of anesthesia, rats is prone,drilling in sensorimotor cortical areas (anterior fontanelle after2.0mm,paramedian2.0mm) according to Paxinos and Watson compilation of the atlas(anterior fontanelle after2.0mm, paramedian2.0mm), using the micro syringeinjected FeCl3solution (concentration is100mmol/L) into the location of under 2.4mm of skull within4minutes, removal of puncture needle after5minutes.Then using the glass ionomer cement insulated and fixed electrode on the cranialsurface, and suture scalp. Skull is fixed three electrode separately at the end ofnasal bone (as a reference electrode placement), the anterior fontanelle before2.0mm, paramedian2.0mm placement, and the EEG system connected to the skullthree electrode, around the drug inject point fix eight stainless steel screwaccording to the spacing of the way, and connect with the EIT system. The EITsystem’s excitation current amplitude is set to1.25mA, and frequency is50kHz.Experiment one is single EIT monitoring, the behavioral seizures in III class aboveand longer than15seconds as an effective attack. Experiment two using EIT andEEG synchronous monitoring at equal pace, the behavioral seizures in III classabove and EEG recording ictal time greater than15seconds as an effective attack.All rats are performed3hours of monitoring, recording and analysis of results ofmonitoring. The results of experiments: all the ten rats, record a total of63epileptic seizures, and the seizures can be divided into the following forms:1. The42episodes of the EIT monitoring of the seizuer lesion area image turns red(lower resistivity) and behavioral seizures occur simultaneously; the7episodesof the EIT detection of the lesion area ten seconds after the lesion area turn red;2.The2episodes of the EIT monitoring of the lesion area image turns blue andbehavioral seizures occur simultaneously;3. The5episodes of the EIT monitoringof the area around lesion area turns red, the lesion area has no obvious change, the7episode of the EIT monitoring image without obvious changes. Results of theexperiment two: all the5rats, record a total of35epileptic seizures. Monitoringresults in the following case:1. The22episodes of the EIT monitoring of thelesion area image turns red and behavioral seizures occur simultaneously, the7episode of the EIT monitoring of the lesion area image turn red after10secondsezure starting;2. The2episodes of the EIT monitoring of the lesion area image turns blue and behavioral seizures occur simultaneously;3. The4episodes of theEIT monitoring image without obvious changes.Through the series of experiments, we can take these following conclusions:1.When the ferric chloride in epileptic rat begin epileptic seizure, focus area’selectrical impedance changes regularly (lesion area of electrical impedance isreduced);2. Using the EIT imaging findings can reflect the epileptic rats of epilepsyfocus size and position relatively well;3. We can take EIT and EEG synchronoustechnique to monitor the rats epileptic seizure. To sum up, through the electricalimpedance tomography for is able to response is able to better reflect the episodesfocus area electrical impedance changes, because the people don’t understand thechanges of the epileptic electrical impedance image deeply and the devices are notvery sensitivity in detecting the seizures, using EIT in clinic still has a long way togo.