Lei's team at the Institute of Medicine of Northwestern Polytechnical University applied electrical impedance tomography to locate epileptogenic foci and detect and predict seizures

Surgical resection and feedback electrical stimulation are two treatments
for patients with refractory epilepsy.
However, at this stage, there are still problems
such as inaccurate localization of lesions and inability to predict seizures in real time.
Electrical impedance Tomography (EIT), which is sensitive to impedance changes caused by blood flow and cell swelling, could be a new way to
locate epileptic foci and predict seizures.

Wang Lei's team at the Institute of Medical Science of Northwestern Polytechnical University has been committed to the research of
electrical impedance tomography applied to epileptic foci localization, seizure detection and prediction.
Wang's research shows that EIT can detect and image impedance changes
within the lesion during seizures.
However, there is some controversy about the change in impedance during seizures, which may be due to
a variety of factors.
Among them, the selection of animal epilepsy model is also one of the
important factors.
On September 12, 2022, the team published a review of "Animal models for epileptic foci localization, seizure detection, and prediction by electrical impedance tomography" online in WIREs Cognitive Science.
The characteristics of various animal epilepsy models are systematically reviewed, and conditions that may be suitable for animal epilepsy models for EIT research are proposed (Figure 1).

Figure 1

Drug-refractory epilepsy is one of the stubborn diseases of the nervous system, and the key to treatment is the accurate localization of epileptic foci and accurate prediction
of seizures.
Due to the limitations of existing technologies in locating refractory epileptic foci and predicting seizures, the need to develop new technologies and methods is urgent
.
EIT has been shown to have the feasibility of detecting and imaging cellular swelling and changes in cerebral blood flow during seizures, but the trend of impedance changes during seizures is controversial
in animal model studies.
In response to this problem, the authors first reviewed the research process of EIT in the field of epilepsy, and discussed and analyzed the possible causes of
controversy for the first time.
In addition to the different carrier frequencies of current application, the different timescales of seizures that each group focuses on, and the differences in researchers' understanding of the mechanism of seizures, the choice of epilepsy model also has a great impact on the research results, but it is often easily overlooked
.
Therefore, the selection of a suitable epilepsy model is crucial for the study of EIT to help researchers more accurately explore the impedance changes
in the pre-seizure and seizure periods before the method enters clinical application.

The authors systematically reviewed the current mature animal epilepsy models, mainly including chemical ignition models, electrical stimulation ignition models and genetic models
.
In the chemical ignition model, hyrenic acid, pirocapine, penicillin, etc.
have been applied to EIT-based seizure detection research, and the authors summarize the seizure mechanism and pathological characteristics of various models and analyze their limitations
in the study.
The electrical stimulation model is the most widely used epilepsy model in EIT research, mainly including cortical diffusion inhibition model, hippocampal epilepsy AD model, neocortical epilepsy AD model, etc
.
However, the most obvious drawback of the electrical stimulation model is that it lacks cell specificity and cannot mimic real human epilepsy
.
Genetic models have not been used in EIT studies due to their complex modeling process and expensive experimental costs, but they are one of
the closest models to real human epilepsy 。 Based on the limitations of the epilepsy model currently used in the study, the authors propose conditions that may be applicable to the epilepsy model of EIT study based on how EIT works: the behavioral, pathological, and EEG features of the model are highly similar to human refractory epilepsy; Has a certain stability, can repeat epileptic activity many times; During the establishment of the model, there will be no impedance changes unrelated to seizures due to local brain injury; The model has clear and sufficiently long interictal and episodic periods
.
The authors propose that chemical models and genetic models are more suitable for EIT research
due to the working characteristics of EIT.
In chemical models, intraperitoneal injection-induced chronic epilepsy models may be closer to real human seizures
.

In summary, this paper systematically reviews the research process of EIT in the field of epilepsy, reviews the current mature epilepsy models and epilepsy models that have been applied to EIT research, summarizes the problems existing in EIT research, and proposes animal epilepsy models suitable for EIT research, so as to lay a solid foundation for EIT to locate epileptogenic foci, detect and predict seizures, and provide important support
for EIT to be put into clinical use.

Corresponding author

Wang Lei

Assistant Professor of the Institute of Medicine, Northwestern Polytechnical University, Master Supervisor

Wang Lei's team has been committed to the study of electromagnetic characteristics of human living biological tissues; Electrical impedance tomography is a new method to dynamically monitor major craniocerebral diseases
such as stroke and epilepsy.
In recent years, he has published a number of high-level papers in top journals including IEEE TBME and other fields with the first/communication (including common); Editorial Board Member
of the Journal of Biomedical Engineering Research.
If you are interested in joining the team, please send an email to bmewanglei@nwpu.
edu.
cn
.

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