AU2021104416A4 - Device for measuring severity estimation in muscular atrophy & inflammation of muscles. - Google Patents

Abstract

The present invention provides a user-friendly device which can also be used by layman for accurate assessment of muscle strength using EMG without requiring a medical expert, and also for assessing the muscle strength using EMG test. The proposed device also detects the muscle strength parameters such as muscular dystrophy, inflammation of muscles and pinched nerves in an easy and rapid manner. 2 Figure 1: Active AMG electrodes Electrode Tendinous Innervation Zone Insertion Figure 2: The ideal position of the electrode between innervate zone (motor unit) and tendinous insertion (belly of muscle)

Description

Figure 1: Active AMG electrodes

Electrode Tendinous Innervation Zone Insertion

Figure 2: The ideal position of the electrode between innervate zone (motor unit) and tendinous insertion (belly of muscle)

EDITORIAL NOTE 2021104416

There are 8 pages of description.

DEVICE FOR MEASURING SEVERITY ESTIMATION IN MUSCULAR ATROPHY & INFLAMMATION OF MUSCLES.

Summary

The device presented here performs the EMG test to determine the muscle strength for detecting muscle strength parameters like muscular dystrophy, inflammation of muscles. The muscle strength parameters are determined by placing the electrodes on the muscle. After passing the electrical signal through electrodes into the nerve / muscle, the device compares the measured nerve conduction parameters and muscle strength parameters with standard data to calculate the extent of nerve damage and displays the result in a display unit of the device.

Other objects, advantages and features of the present invention will become more apparent from the following detailed description and claims, taken in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed for the purpose of illustration only and are not intended as a definition of the limits of the invention.

Also, the device performs the EMG test to determine muscle strength parameters such as muscular dystrophy, inflammation of muscles and pinched nerves

Then, the device compares the measured muscle strength parameters with standard data to calculate the extent of muscular damage and displays the result in a display unit of the device.

Background of Work:

We thought of developing a device which can be made available to such patients, who are suffering from muscular damages. It can lead to reduction in medical expenses as a high percentage of population is suffers from muscular problems. A literature survey of technology affirms the feasibility of a technology which can measure the health of neurons by application of electrical signal and checking the response can help us in measuring the muscular damage caused. It uses the simple concept that healthy nerves are good conductor of electrical signals. Our wearable device is capable of detecting the problems of neural damage at an early stage, empowering the patient to take adequate steps for early treatment, and in some cases, preventing a possible surgical intervention. Advancements in microcontrollers have opened up the possibilities to design such a device, which will use principles of electromyography in an intuitive wearable manner for self-diagnosis of neural damage.

Clinically, electromyography (EMG) is being used as diagnostic tool for neurological disorders. It is frequently being used for assessment of patients with neuromuscular diseases. The size and complexity of the machines remain an issue for general purpose use. As technology has advanced, we envision that a wearable, user-friendly device will be possible and will be a disruptive product in the space of medical diagnostics. The number of people who are likely to use it is also very large and increasing. There also persists a huge scarcity of such diagnostic facilities, which are time consuming and expensive.

The EMG test is performed to measure the muscle strength by recording the electrical signals moving through the muscles. In order to perform this EMG test, the same electrode used for nerve conduction test is used and it is inserted into the muscle for determining the muscle strength parameters. This test helps in detecting the presence, location, and extent of any disease that may damage the nerves and muscles. If the nerves going to the muscles are damaged, clear signals cannot be obtained. Therefore, the muscles won't respond well. In the other case, if the muscles are not damaged, clear signals can be obtained and the muscles respond well to determine the muscle parameter. Hence, based on this muscle parameters are measured.

Also, the measurement of muscle strength parameters using EMG test aids in determining the estimation of DPN severity.

EMG has some limitations as well. Since these electrodes are applied on the skin, they are generally used for superficial muscles only. Crosstalk from other muscles is a major problem. Their position must be kept stable with the skin; otherwise, the signal gets distorted. Gelled EMG electrodes contain a gelled electrolytic substance as an interface between skin and electrodes.

Detailed Description:

The device is wearable around the area with the help of Velcro having surface EMG electrodes (NON INVASIVE). Conducting electrode attached to the device comes in contact with the affected area of skin with help of special conducting gel. Thus the circuit is complete as both the electrodes are attached to a monitor screen which displays the intensity and time of signals sent and received respectively. The theory behind these electrodes is that they form a chemical equilibrium between detecting surface and the skin of the affected area through electrolytic conduction, so that current can flow into the electrode. The final result as well as the interpretation is flashed on the monitor after each session. The monitor will indicate the auto setup, start of the working and finally produce a beep sound at the termination of the working of the device while showing the readings of damage in the screen.

The muscle reflexes to an electric shock which is monitored with the help of the electrodes. The concept has been visually presented in Figure 1.The conducting electrode is attached to the device which is worn around the affected leg or arm feeling the tingling or loss in sensation. The sensation losses of the limbs can be simply checked from time to time by turning on the device and reading the device's interpretation of the signal. Our user friendly screen display the extent of nerve damage as well as provide hint on the area affected and need for a physician's consultation, if any. 1. Design, Development, or choice of electrodes (4 acupoints), conducting gel, duct tape or Velcro to place the electrodes on skin (ankle or elbow region), an amplifier, a detector and a monitor for showing the result. 2. Tests is carried out, lasting for 15-20 minutes, in which some transmitting electrodes is placed along with receiver electrodes with the help of conducting gel on the skin surface of the patient which is tied by Velcro/duct tape, so that the electrodes cannot move from the specified place. 3. Development of analog circuit for signal generation and processing has helped to enable the device to impart minimal desired amount of electrical signal at its transmitting electrodes to the skin surface of the patient which is then be passing through effected nerves and ultimately be received by the receiver electrodes.

4. Development of digital circuit and visualizing interface (monitor) for displaying the time taken to complete one cycle, at the same time recording the value for further processing.

According to the present invention, the cuff is wrapped over the leg of the patient for nerve conduction test to determine exact location of the sural nerve region and thereby overcome location uncertainty and also for EMG test to determine muscle strength. That is, the cuff contains an array of simulation electrodes that can send the electrical pulses to the wide area of sural nerve region and a wide array of bio-sensing electrodes for sensing and signal acquisition. So that, a layman can also use this device for assessing the nerve parameters and muscle strength parameters without the need of medical expert.

In accordance with the present invention, the cuff can be wrapped either to the left or the right leg of the patient depending on the affected area as the limb impedance of both the leg are equal.

The cuff is placed against the patient sural nerve such that cathode is located over the sural nerve as the sural nerve passes behind lateral malleolus and sensing unit is located over the sural nerve as nerve approached the Achilles tendon about 9 cm from cathode. After placing the electrodes on sural nerve, the device performs the nerve conduction velocity (NCV) test to determine sural nerve conduction parameters such as, the onset conduction velocity and sensory response amplitude and the EMG test by placing the electrodes into muscles to determine the muscle parameters such as muscular dystrophy, inflammation of muscles and pinched nerves. Further, the device compares the measured nerve conduction parameters and muscle strength parameters with standard data to calculate the extent of nerve damage and displays the result in a display unit of the device.

Electrode Design and Signal Acquisition: Surface EMG electrodes provide a non-invasive technique for measurement and detection of EMG signal. The theory behind these electrodes is that they form a chemical equilibrium between the detecting surface and the skin of the body through electrolytic conduction, so that current can flow into the electrode. These electrodes are simple and very easy to implement. In contrast, application of needle and fine wire electrodes require strict medical supervision and certification. Surface EMG electrodes require no such formalities. Surface EMG electrodes have found their use in motor behaviour studies, neuromuscular recordings, sports medical evaluations and for subjects who object to needle insertions such as children. Apart from all this, surface EMG is being increasingly used to detect muscle activity in order to control device extensions to achieve prosthesis for physically disabled and amputated population. Surface

Oxidation and reduction reactions take place at the metal electrode junction. Silver - silver chloride (Ag-AgCl) is the most common composite for the metallic part of gelled electrodes. The AgCl layer allows current from the muscle to pass more freely across the junction between the electrolyte and the electrode. This introduces less electrical noise into the measurement, as compared to equivalent metallic electrodes (e.g. Ag). Due to this fact, Ag-AgC1 electrodes are used in over 80% of surface EMG applications. Disposable gelled EMG electrodes are most common; however, reusable gelled electrodes are also available. Special skin preparations and precautions such as (hair removal, proper gel concentration, prevention of sweat accumulation etc.) are required for gelled electrodes in order to acquire the best possible signal. We will conduct experiments with commercially available gelled EMG electrodes, such as that of Delsys. They are also available as active electrodes which have an amplifier with high input impedance and power cables as shown below (Figure

Application of surface EMG electrodes requires proper skin preparation beforehand. In order to obtain a good quality EMG signal, the skin's impedance must be considerably reduced. For this purpose, the dead cells on the skin e.g. hair must be completely removed from the location where the EMG electrodes are to be placed. It is advisable to use an abrasive gel to reduce the dry layer of the skin. There should be no moisture on the skin. The skin should be cleaned with alcohol in order to eliminate any wetness or sweat on the skin. In most cases, two detecting surfaces (or EMG electrodes) are placed on the skin in bipolar configuration. To acquire best signals, the EMG electrode should be placed at a proper location and its orientation across the muscle is critically important. The surface EMG electrodes should be placed between the motor unit and the tendinous insertion of the muscle, along the longitudinal midline of the muscle. The distance between the centre of the electrodes or detecting surfaces should only be

1-2 cm. The longitudinal axis of the electrodes (which passes through both detecting surfaces) should be parallel to the length of the muscle fibres. The belly of the muscle has been widely accepted as the best location, due to the target muscle fibre density being the highest. Figure 3 shows the proper EMG electrode placement. When the electrodes are arranged in this manner, the detecting surfaces of both electrode intersect the muscle fibres, and as a result, a much improved signal is observed.

The EMG signal's amplitude lies in between 1-10 mV, making it a considerably weak signal. The most dominant signal are in frequency range between 50-150 Hz. The EMG signal is heavily influenced by noise, as shown in Figure 4. The noise signals can have a variety of characteristics depending on their sources, such as by electromagnetic radiation sources e.g. radio transmission devices, fluorescent lights and power line interference from electrical wires. These interferences are extremely difficult to avoid from external means. Noise can also be generated from motion artefact. The two main sources of this noise are instability of electrode skin interface and movement of the electrode cable, typically lying in the range of 0-20 Hz. It can be reduced by properly setting up the EMG equipment and circuitry. The signal to noise ratio thus becomes an important parameter in our circuit design consideration.

The signals from the two EMG surfaces in bipolar configuration are connected to a differential amplifier. The differential amplifier suppresses the common noise signals to both inputs and then amplifies the difference. The limitations of the monopolar configuration are catered for by this configuration. This is the most commonly used electrode configuration. The bipolar EMG electrode configuration is shown in Figure 5.

The noise frequencies contaminating the raw EMG signal can be high as well as low. Low frequency noise can be caused from amplifier DC offsets, sensor drift on skin and temperature fluctuations and can be removed using a high pass filter. High frequency noise can be caused from nerve conduction and high frequency interference from radio broadcasts, computers, cellular phones etc. and can be deleted using a low pass filter. In order to remove these high and low frequencies, high pass and low pass bio-filters, of second order, will be implemented. (Example circuit diagrams are illustrated in Figure 6)

BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1: Active AMG electrodes

FIG. 2 is a block diagram representing the signal manipulation unit of the device of the present invention; and

Figure 3: The ideal position of the electrode between innervate zone (motor unit) and tendinous insertion (belly of muscle)

Figure 4: EMG spectrum and noise influence on this spectrum

Figure 5: Bipolar Configuration Figure 6 : High Pass (above) and Low Pass (below) Filter circuit design

Claims (4)

1. The device as claimed in claim 1, wherein the device performs the EMG test to measure muscle strength parameters such as muscular dystrophy, inflammation of muscles, pinched nerves, peripheral nerve damage, etc.

2. The device as claimed in claim 1, wherein the simulation electrodes are inserted into the muscles for performing EMG test

3. A method for performing an EMG test, comprising the steps of: a) wrapping a cuff over leg of the patient; b) pressing the power button to input power to the device; c) sending the electrical simulation to sural nerve / muscle region via simulation electrodes placed on the cuff by inputting the pulse from external event; d) sensing the electrical activity of the sural nerve / muscle region and providing the low impedance path to the electrical simulation with bio signal sensing electrodes placed on the cuff; e) acquisition of bio-potential signal with a signal acquisition unit; f) filtering, smoothing and amplifying the signal with a signal manipulation unit; g) processing the signal with a signal processing unit that consists of a microcontroller to get the muscle strength parameters; h) comparing the obtained/measured muscle strength parameters with standard data to calculate the extent of muscle damage; i) displaying the test results on a display unit of the device.

4. The method as claimed in claim 3, wherein the external event can be any one of: send pulse button pressed, response from bio-sensor unit or input from user.

EDITORIAL NOTE 2021104416

There are 4 pages of drawings only.

Figure 1: Active AMG electrodes

Figure 2: The ideal position of the electrode between innervate zone (motor unit) and tendinous insertion (belly of muscle)

Figure 3 : signal manipulation unit of the device of the present invention;

Figure 4: EMG spectrum and noise influence on this spectrum

Figure 5: Bipolar Configuration

Figure 6 : High Pass (above) and Low Pass (below) Filter circuit design