A closed-loop vagus nerve stimulator based on scalp EEG

Abstract

The present invention discloses a closed-loop vagus nerve stimulator based on scalp electroencephalogram (EEG), including a signal acquisition module, a scalp electroencephalogram (EEG) signal processing module and a vagus nerve stimulator. The signal acquisition module is connected to the scalp electroencephalogram (EEG) signal processing module; the signal acquisition module is used to acquire scalp electroencephalogram (EEG) signals; the scalp electroencephalogram (EEG) signal processing module is used to process the scalp electroencephalogram (EEG) signals, determine whether epilepsy occurs according to the processed scalp electroencephalogram (EEG) signals, and transmit the epilepsy occurrence signal to the vagus nerve stimulator; the vagus nerve stimulator is used to generate a stimulation pulse after receiving the signal. When the scalp electroencephalogram (EEG) signals are acquired and it is determined that epilepsy occurs, the vagus nerve stimulator automatically generates a stimulation pulse in time to stimulate, forming a closed-loop stimulation. Compared with an open-loop vagus nerve stimulator, the stimulation parameters are adjusted in time and the stimulation effect is ideal; by acquiring scalp electroencephalogram (EEG) signals, there is no need for craniotomy, the surgical trauma is small, the accuracy of epilepsy judgment is high, and the false detection rate is low.

Description

Technical Field

[0001] The present invention relates to a vagus nerve stimulator, in particular to a closed-loop vagus nerve stimulator based on scalp electroencephalogram (EEG). Background Art

[0002] Epilepsy is a common brain disorder. While most epilepsy symptoms can be alleviated with medication, some cases are drug-resistant and are considered refractory. Vagus nerve stimulators are a treatment option for refractory epilepsy. However, most existing vagus nerve stimulators are open-loop systems that lack the ability to detect epileptic seizures in real time and cannot achieve closed-loop stimulation.

[0003] Currently, there are some closed-loop vagus nerve stimulators in the existing technology that have the function of real-time detection of epileptic seizures and implementation of stimulation, including closed-loop vagus nerve stimulators that use intracranial EEG signal feedback and closed-loop vagus nerve stimulators that use ECG signal feedback.

[0004] However, the above-mentioned open-loop vagus nerve stimulator and closed-loop vagus nerve stimulator have the following problems:

[0005] 1) The stimulation parameters of traditional open-loop vagus nerve stimulators are not adjusted in time, the stimulation effect is not ideal, and the battery inside the vagus nerve stimulator needs to be replaced through a second operation after the energy is exhausted.

[0006] 2) A closed-loop vagus nerve stimulator that uses intracranial EEG signal feedback needs to extract nerve action potentials from the diseased area of ​​the brain, and the surgical trauma caused by craniotomy and placement of collection electrodes is severe.

[0007] 3) The closed-loop vagus nerve stimulator using ECG signal feedback has low epilepsy warning accuracy and high false detection rate. Summary of the Invention

[0008] Purpose of the invention: In view of the above shortcomings, the present invention provides a closed-loop vagus nerve stimulator based on scalp EEG that can stimulate timely, accurately and with high accuracy.

[0009] Technical solution: To solve the above problems, the present invention adopts a closed-loop vagus nerve stimulator based on scalp EEG, including a signal acquisition module, a scalp EEG signal processing module and a vagus nerve stimulator; the signal acquisition module is connected to the scalp EEG signal processing module; the signal acquisition module is used to acquire scalp EEG signals; the scalp EEG signal processing module is used to process the scalp EEG signals, determine whether epilepsy occurs based on the processed scalp EEG signals, and transmit the epilepsy occurrence signal to the vagus nerve stimulator; the vagus nerve stimulator is used to generate stimulation pulses after receiving the signals.

[0010] Furthermore, the scalp EEG signal processing module includes a multi-channel preamplifier connected to the signal acquisition module, an epilepsy seizure detector connected to the multi-channel preamplifier, and a first data transmission unit connected to the epilepsy seizure detector; the epilepsy seizure detector is used to process the scalp EEG signal to determine whether epilepsy occurs; the first data transmission unit is used to transmit epilepsy occurrence signals.

[0011] Furthermore, the vagus nerve stimulator includes a second data transmission unit, a second microprocessor connected to the second data transmission unit, and a pulse generator connected to the second microprocessor; wireless signal transmission is performed between the second data transmission unit and the first data transmission unit, and the second data transmission unit is used to receive epilepsy occurrence signals; the second microprocessor is used to send a working instruction to the pulse generator after receiving the epilepsy occurrence signal, and the pulse generator is used to generate stimulation pulses.

[0012] Furthermore, the vagus nerve stimulator also includes a wireless energy receiver, which is used to receive wirelessly transmitted electrical energy and supply power to the electrical structures in the vagus nerve stimulator.

[0013] Furthermore, the vagus nerve stimulator also includes an electrode-tissue impedance extractor, the pulse generator is provided with a stimulation electrode, the stimulation electrode is used to transmit the stimulation pulse to the vagus nerve, and the electrode-tissue impedance extractor is used to measure the impedance between the stimulation electrode and the vagus nerve.

[0014] Furthermore, the vagus nerve stimulator also includes a temperature sensor, which is used to detect tissue temperature.

[0015] Furthermore, it also includes a controller, which performs wireless signal transmission with the second data transmission unit. The controller is used to display the working status of the scalp EEG signal processing module and the vagus nerve stimulator, and to adjust the parameters of the stimulation pulse output by the vagus nerve stimulator.

[0016] Furthermore, the signal acquisition module includes a dry electrode.

[0017] Furthermore, the dry electrode is arranged on a wearable helmet.

[0018] Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages: when the scalp EEG signal is collected and it is determined that epilepsy has occurred, the vagus nerve stimulator automatically generates stimulation pulses in time to stimulate, forming a closed-loop stimulation. Compared with the open-loop vagus nerve stimulator, the stimulation parameters are adjusted in time and the stimulation effect is ideal; by collecting scalp EEG signals, there is no need for craniotomy, the surgical trauma is small, the accuracy of epilepsy judgment is high, and the false detection rate is low. The vagus nerve stimulator receives electrical energy through a wireless energy receiver to power electrical equipment, and there is no need to replace the internal battery of the vagus nerve stimulator through a secondary operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG2 is a schematic block diagram of the structure of the closed-loop vagus nerve stimulator of the present invention;

[0020] Figure 2 Shown is a schematic diagram of the closed-loop vagus nerve stimulator of the present invention when in use;

[0021] Figure 3 FIG2 is a schematic diagram showing the dry electrodes and scalp EEG signal processing module of the present invention disposed in a wearable helmet;

[0022] Figure 4 The following is a schematic diagram of the controller APP interface. DETAILED DESCRIPTION

[0023] like Figure 1 and Figure 2 As shown in FIG, a closed-loop vagus nerve stimulator based on scalp EEG in this embodiment includes a signal acquisition module, a scalp EEG signal processing module and a vagus nerve stimulator. The signal acquisition module includes a plurality of dry electrodes 10. The dry electrodes 10 serve as acquisition electrodes for acquiring scalp EEG signals. Figure 3 As shown, the dry electrode 10 is mounted on a wearable helmet 20, which has corresponding openings for the dry electrode 10 to pass through. The wearable helmet 20 serves as a support structure to facilitate the dry electrode 10 to collect scalp EEG signals. The dry electrode 10 is connected to a scalp EEG signal processing module 30.

[0024] The scalp EEG signal processing module 30 includes a multi-channel preamplifier 301, a first microprocessor 302, a first data transmission unit 303, and a charging unit 304. The multi-channel preamplifier 301 is connected to the dry electrodes 10 to amplify the collected scalp EEG signals. The first microprocessor 302 includes an analog-to-digital converter and an epileptic seizure detector. The output of the multi-channel preamplifier 301 is connected to the input of the analog-to-digital converter, which is connected to the input of the epileptic seizure detector. The output of the epileptic seizure detector is connected to the input of the first data transmission unit 303. The charging unit 304 has an input connected to an external power supply and an output connected to the multi-channel preamplifier 301, the first microprocessor 302, and the first data transmission unit 303. The charging unit 304 provides power to the power-consuming modules in the scalp EEG signal processing module 30. In this embodiment, the charging unit 304 is a wired charging unit.

[0025] During an epileptic seizure, the patient's scalp EEG signal has certain special forms, including action potentials (spikes, spikes, complex waves) and local field potentials. The spikes in the action potential have a steep waveform, while the local field potential reflects the excitatory characteristics of local neurons and the inhibitory properties of postsynaptic potentials. It contains a very large amount of information and can reflect the changing characteristics of the chronic potential in the target area. Since the action potential and local field potential signals are very weak, a multi-channel preamplifier 301 is required to amplify the collected scalp EEG signals, and the amplified signals enter the multi-channel analog-to-digital converter built into the first microprocessor 302. After being digitized by the multi-channel analog-to-digital converter, the scalp EEG signals will then be sent to the epileptic seizure detector to determine whether an epileptic seizure has occurred. The first microprocessor 302 transmits the seizure information to the first data transmission unit 303 through the asynchronous communication serial port, and the first data transmission unit 303 uses Bluetooth communication to transmit the information to the vagus nerve stimulator 40.

[0026] An epileptic seizure detector can establish a coastline parameter detection model based on scalp EEG data acquired over a period of time. The coastline parameter is the cumulative length of the field potential signal curve within a given time window. Its value increases significantly when the neural signal potential changes, thus having a clear physical meaning. To improve the accuracy of the detection model and reduce false epilepsy detections, it is necessary to determine whether the amplitude and slope of the EEG signal exceed a threshold before calculating the coastline parameter. Only when the amplitude, slope, and coastline parameter of the EEG signal all exceed the threshold does the detection model determine that an epilepsy has occurred. Another method for scalp EEG signal processing and epilepsy detection is to establish an epilepsy signal detection model based on wavelet transform based on scalp EEG data acquired over a period of time. This algorithm uses an improved wavelet threshold function to remove artifacts from epilepsy signals, integrates wavelet transform resolution analysis and nonlinear dynamics-related algorithms to extract epilepsy EEG signal features, and utilizes a nonlinear classifier within a support vector machine to detect and classify epilepsy signals. It should be noted that epilepsy detection algorithms based on scalp EEG signals are not limited to the two specific algorithms described above; in practical applications, more complex or simpler detection algorithms can be used.

[0027] The vagus nerve stimulator 40 is housed in a biocompatible ceramic housing and includes a second data transmission unit 402, a second microprocessor 403, a pulse generator 404, a wireless energy receiver 401, an electrode-tissue impedance extractor 405, and a temperature sensor 406. The input of the second data transmission unit 402 receives the wireless signal transmitted by the first data transmission unit 303, and the output of the second data transmission unit 402 is connected to the input of the second microprocessor 403. In this embodiment, the second microprocessor 403 is an ultra-low-power microprocessor. The output end of the second microprocessor 403 is connected to the input end of the pulse generator 404, the output end of the pulse generator 404 is connected to the input end of the electrode-tissue impedance extractor 405, the output end of the electrode-tissue impedance extractor 405 is connected to the input end of the second microprocessor 403, the output end of the temperature sensor 406 is connected to the input end of the ultra-low power microprocessor 405, and the wireless energy receiver 401 is connected to the second data transmission unit 402, the second microprocessor 403, the pulse generator 404, the electrode-tissue impedance extractor 405, and the temperature sensor 406 to power the power module in the vagus nerve stimulator 40. In this embodiment, the pulse generator 404 adopts a switch resistor array pulse generator.

[0028] Wireless energy receiver 401 and wireless energy transmitter 50 perform wireless energy transmission. In this embodiment, wireless energy receiver 401 uses a distance-frequency adaptive magnetic resonance energy receiver, and wireless energy transmitter 50 uses a distance-frequency adaptive magnetic resonance energy transmitter. Wireless energy receiver 401 receives wireless energy from wireless energy transmitter 50 to power the power module in vagus nerve stimulator 40, avoiding the disadvantage of requiring a secondary surgery to replace the battery after the internal battery of the vagus nerve stimulator is exhausted. The specific implementation technology of wireless energy transmission adopts existing technology, such as the technical solution in patent CN201811501220.7, and will not be repeated here.

[0029] Second data transmission unit 402 receives epileptic seizure information from first data transmission unit 303 via Bluetooth communication. It also receives control information from controller 60 via Bluetooth communication. This control information includes appropriate stimulation pulse parameter information and control instructions. This information is then transmitted to second microprocessor 403 via an asynchronous serial communication port. After receiving this information, second microprocessor 403 sends a working command to switched resistor array pulse generator 404. Switched resistor array pulse generator 404 generates stimulation pulses to suppress epileptic seizures. Pulse generator 404 includes stimulation electrode 4041 and extension lead 4042. Stimulation electrode 4041 is clamped onto the vagus nerve 70 on the left side of the neck. Extension lead 4042 transmits pulses to stimulation electrode 4041 and vagus nerve 70. The suppression principle circuit setting of the switched resistor array pulse generator adopts the existing technology such as the technical solution in patent CN201610607640.8. The specific setting of the parameter information of the stimulation pulse can refer to the existing literature: Li Luming, Hao Hongwei. Current status and development trend of implantable neurostimulators [J]. China Medical Devices Journal, 2009, 33., Section 2.3 of which introduces the technical indicators of the vagus nerve stimulator, which will not be repeated here.

[0030] Electrode-tissue impedance extractor 405 communicates bidirectionally with second microprocessor 403 via a single line to determine whether the stimulation electrode is in good contact with the target tissue and whether the lead is damaged. Temperature sensor 406 communicates bidirectionally with ultra-low-power microprocessor 403 via a single line. When the vagus nerve stimulator generates stimulation pulses or wirelessly charges, the temperature sensor issues an alarm if the tissue temperature rises by two degrees Celsius or more.

[0031] like Figure 4As shown, the controller 60 is a mobile phone or tablet App developed based on the Android system, which is wirelessly connected to the first data transmission unit 303 and the second data transmission unit 402 via the Bluetooth module of the App terminal. The App of the controller 60 can display the connection status between the App and the scalp EEG signal processing module 30 and the vagus nerve stimulator 40; the controller 60 can display the working status of the vagus nerve stimulator 40, including information such as the remaining battery life, system standby, battery charging, temperature, bioimpedance and stimulation pulse parameters; the controller 60 can display the working status of the scalp EEG signal processing module 30, including information such as the remaining battery life, system standby, seizure parameters and seizure status (normal, pre-epileptic seizure and epileptic seizure). In addition, the frequency, width and amplitude of the stimulation pulse can also be manually adjusted through the controller 60.

[0032] The controller 60 can also provide a guardian alert function. When an epileptic seizure is detected, the controller 60 will send a text message to the patient's guardian's mobile terminal through the server. The message content includes epileptic seizure information and the patient's current location.

[0033] The closed-loop vagus nerve stimulator in this embodiment uses scalp EEG signal feedback. Compared to open-loop vagus nerve stimulators, stimulation parameters can be adjusted more quickly, resulting in optimal stimulation effects. This eliminates the need for a secondary surgery to replace the vagus nerve stimulator's internal battery. Compared to closed-loop vagus nerve stimulators that use intracranial EEG signal feedback, the surgical procedure is less invasive. Compared to closed-loop vagus nerve stimulators that use ECG signal feedback, the device offers higher epilepsy warning accuracy and lower false positive rates.

Claims

1. A closed-loop vagus nerve stimulator based on scalp electroencephalogram, characterized in that: It includes a signal acquisition module, a scalp EEG signal processing module and a vagus nerve stimulator; the signal acquisition module is connected to the scalp EEG signal processing module; the signal acquisition module is used to collect scalp EEG signals; The scalp EEG signal processing module is used to process the scalp EEG signal, determine whether epilepsy occurs according to the processed scalp EEG signal, and transmit the epilepsy occurrence signal to the vagus nerve stimulator; the vagus nerve stimulator is used to generate a stimulation pulse after receiving the signal; The scalp EEG signal processing module comprises a multi-channel preamplifier (301) connected to the signal acquisition module, an epilepsy attack detector connected to the multi-channel preamplifier (301), and a first data transmission unit (303) connected to the epilepsy attack detector; the epilepsy attack detector is used to process the scalp EEG signal to determine whether epilepsy has occurred; the first data transmission unit (303) is used to transmit epilepsy occurrence signals; The vagus nerve stimulator comprises a second data transmission unit (402), a second microprocessor (403) connected to the second data transmission unit (402), and a pulse generator (404) connected to the second microprocessor (403); wireless signal transmission is performed between the second data transmission unit (402) and the first data transmission unit (303), and the second data transmission unit (402) is used to receive epilepsy occurrence signals; the second microprocessor (403) is used to send a working instruction to the pulse generator (404) after receiving the epilepsy occurrence signal; and the pulse generator (404) is used to generate stimulation pulses; The vagus nerve stimulator also includes an electrode-tissue impedance extractor (405); the pulse generator (404) is provided with a stimulation electrode, the stimulation electrode is used to transmit the stimulation pulse to the nerve tissue, and the electrode-tissue impedance extractor (405) is used to measure the impedance between the stimulation electrode and the nerve tissue; the electrode-tissue impedance extractor (405) communicates bidirectionally with the second microprocessor (403) via a port line to determine whether the stimulation electrode is in good contact with the target tissue and whether the wire is damaged.

2. The closed-loop vagus nerve stimulator according to claim 1, characterized in that: The vagus nerve stimulator also includes a wireless energy receiver (401), which is used to receive wirelessly transmitted electrical energy and to supply power to electrical devices in the vagus nerve stimulator.

3. The closed-loop vagus nerve stimulator according to claim 1, characterized in that: The vagus nerve stimulator also includes a temperature sensor (406), wherein the temperature sensor (406) is used to detect tissue temperature.

4. The closed-loop vagus nerve stimulator according to claim 1, characterized in that: It also includes a controller (60), which performs wireless signal transmission with the second data transmission unit (402), and the controller (60) is used to display the working status of the scalp electroencephalogram signal processing module and the vagus nerve stimulator, and to adjust the parameters of the stimulation pulse output by the vagus nerve stimulator.

5. The closed-loop vagus nerve stimulator according to claim 1, characterized in that: The signal acquisition module comprises a dry electrode (10).

6. The closed-loop vagus nerve stimulator according to claim 5, characterized in that: The dry electrode (10) is arranged on a wearable helmet (20).

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