RU2380032C2 - Device for installation and fixation of electroencephalogram electrodes on animal's head - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to electrical engineering and medical instrument engineering and can be used for recording electroencephalogram and simplifications of manipulations related to installation and fixing of electroencephalogram electrodes on animal's head. The device comprises an integrated electrode board carried with a transparent polymer plate holder. The whole central surface of the board is covered with multiple staggered sockets wherein movable, hollow, tubular, metal electrodes are found. Restricted forward motion of the electrode bodies relative to the socket edges from the face of the plate holder is ensured by a designed widening of the upper part of the tubular electrode body within connection of the demountable contact tip. From the lower side of the board, the electrodes are movably fixed by return springs enclosing the bodies thereof. The springs are fixed with their lower coil within the skin-electrode contact surfaces and freely rest with their upper coils against the lower surface of the plate holder. The internal cavity of the electrode is intended to ensure accessible connection and introduction therein of a contact electrolytic solution or gel. The lateral edges of the plate holder accommodate splines to attach fixation belts, while the back comprises an accessory mounting hole.

EFFECT: application of the invention allows for high-quality electroencephalogram record of animal's brain.

5 cl, 7 dwg

Description

The present invention relates to the field of electrical engineering and medical instrumentation. It can be used to obtain a better graphic recording of the electroencephalogram (EEG) from various parts of the brain of animals and humans and to simplify the manipulations associated with electrophysiological and diagnostic studies.

Well-known analogues of the claimed invention are such medical devices as various head encephalographic helmets arranged in the form of a cap or basket of interwoven rubber bands (belts, elastic bands, silicone tubes, etc.) (US Patent No. 5293867, priority dated March 15, 1994 , US patent No. 3998213, priority from 12/21/1976, FRG patent No. DE 19516659 A1, priority from 11/11/1996) on which EEG electrodes are fixed (USSR patent No. SU 166446 A1, priority from 01/01/1964).

These devices, however, are practically unsuitable for fixing EEG electrodes on the scalp of animals, since they are maximally adapted to the size and shape of the surface of the human head. In this case, the main difficulty encountered in conducting electroencephalographic studies in veterinary medicine is the presence of significant discrepancies in the shapes and sizes of animal skull boxes due to their species, age and breed.

In addition, it is necessary to take into account the fact that the surface of the cortex of the cerebral hemispheres of most warm-blooded animals has significantly smaller sizes and mass compared to those in humans and is projected (topographically and anatomically) only onto the upper, almost flat (or somewhat convex) part their heads (scalp).

In this regard, today, to obtain a record of the biopotentials of the brain of animals, needle electrodes soldered to the ends of cable leads are mainly used. Needle electrodes are inserted subcutaneously over the corresponding area of the cerebral cortex and remain under the skin throughout the entire EEG recording session. Moreover, the resulting curve is often distorted due to the presence of a pain stimulus, which is especially intensified when the animal makes movements and turns of the head.

The need to sterilize the needle electrodes and the skin surface of the scalp before each session of recording electrophysiological parameters also complicates the conduct of these manipulations.

The wide rubber tape used as an alternative to needle electrodes (with patch electrodes fixed on its surface) has the disadvantage of having to hold it with your hands throughout the entire EEG recording time, which is possible only in the presence of an assistant assistant. In addition, animals often show concern about such an unusual “head fixation”, and this affects their mental state during the recording of indicators (and hence the shape of the resulting EEG curve). In addition, any movements of the animal’s head are accompanied by sliding and displacement of the electrodes along the skin-wool surface moistened with electrolyte gel, and accordingly artifacts arise in the resulting graphic displays.

Therefore, the task of the claimed invention was the development of a device capable of providing when using it:

- quick and high-quality installation and fixation of several electrode pairs on the animal’s head at the same time and their connection to standardized electrophysiological equipment;

- adaptability within a fairly wide range of variability of the external dimensions and surface shapes of the cranial vault of animals;

- good contact with the skin surface;

- maximum reduction in the load on the psyche of the animal during the session of recording EEG;

- saving labor time and labor;

- reliability, durability, ease of handling and maintenance;

- high-quality recording of the electroencephalogram.

The task and technical result are achieved thanks to a new set of essential structural features of the claimed device, which is a kind of electrode board (Fig. 1) made in the form of a transparent (or translucent), flat (or somewhat dome-shaped), polymer plate-holder ellipsoid (or rounded) , octagonal) form (1) with holes (2) inside it, inside of which hollow, cylindrical electrodes (3) are installed, made of any corrosion-resistant th metal or alloy (copper, brass, bronze, stainless steel, silver, silver chloride with the application of the coating, a gold amalgam, etc.). These electrodes are arranged symmetrically, in a checkerboard pattern, on both sides of the central axis of the holder plate. The outer diameter of each of the electrodes and the inner cross-section of the corresponding holes of the holder plate should be dependent on which the free position and movement of the middle part of the electrode body is perpendicular to the surface of the board, subject to the condition that the central axis can deviate from the direction vector of the translational motion of the electrode body. Depending on the overall dimensions of the board, the outer diameter of the electrode housing can vary from 1 to 10 mm. The diameter of the upper part (cap) of each electrode must exceed the diameter of the corresponding holes in the holder plate, which can technically be achieved by flaring the outer edge of the cylindrical electrode housing (3), soldering, fixing the retaining ring or washer. On the opposite side of the holder plate, the electrodes are movably fixed by means of preloaded and fixed return springs (4), the spiral turns of which are located around the protruding surfaces of the electrode housings. The upper turns of each spring should abut against the surface of the holder plate (Fig. 2), and its lower part should be fixed by means of a retaining ring (3b) or by soldering the lower coil of the spring (3c) in the immediate vicinity of the edge of the electrode housing forming its contact surface .

When mechanical pressure is exerted on the surface of the holder plate (when the device is mounted on the animal’s head during its preparation for work), its partial displacement in the downward direction (along the electrode housings) occurs, causing compression of the springs (4a) (Fig. 2B). The elastic forces arising in the springs provide stable mechanical pressure of their upper turns on the lower surface of the holder plate, and the lower ends of the electrodes on the scalp surface (7). In this case, the mechanical pressure and load on the individual electrodes (and the corresponding springs) will be distributed unevenly, which is due to the features of the surface anatomical relief formed by the arch of skull bones and overlying tissues. However, any level of degree of deformation of each individual spring will be sufficient to ensure electrical contact of the electrode with the skin surface, as the main role is played by their additional (provided by the standard method) wetting with a solution of electrolyte or electrolyte gel. The design of the device provides for the direct introduction of such a special electrolyte gel (or a cotton swab soaked in NaCl solution) into the internal cavity of the electrode sleeve. Further, when connecting (according to the TOUCH PROOF “socket” principle) to the plug connector electrode (8), the outer diameter of which should be correspondingly slightly smaller than the diameter of the internal section of the electrode sleeve, some of the electrolyte will be forced out of its internal cavity (according to the “piston” principle cylinder ”) from the side of the lower end of the electrode (Photo 1). In this case, dosed wetting of the surfaces of the skin and hair covering will occur in places of their contact with the contact surface of the electrodes, which makes it possible to register brain impulses without shaving hair and wool in places of electrode application.

The transparency of the polymeric material (plexiglass) from which the holder plate is made provides additional control over the state of the electrodes before and during the EEG recording session, and the upper parts of their cases with caps (3) protruding above the board surface allow easy access to the electrodes for their connection and manual correction of their position in order to optimally adapt the electrode board mounted on the head to the shape of the outer surface of the scalp.

The fixation of the working position given to the electrode board is ensured by the tension of the fixing belt or elastic (rubber) tape (6), the free ends of which are fixed in special slots (5) (or in another way) located on the side parts of the holder plate, and the middle part is under the chin animal.

In order to provide additional stability of the position of the electrode board during the EEG recording session, a special hole (slot, fasteners, etc.) (5a) is provided in the central back of the holder plate (5a), through which it can be additionally fixed with an elastic cord fixed the other, free end on the collar (or on a tuft of wool captured by the clip). This additional measure of fixation is aimed at counteracting the displacement of the device in the nasal direction caused by sharp tilts of the animal’s head forward.

The dimensions of the device and, accordingly, the sizes of all its constituent components can vary, changing congruently in proportions, depending on the purpose of its use regarding the size of the head of the animal under study.

However, the same device can be used within a wide range of variability of the external dimensions and surface shapes of the cranial vault of animals. This is ensured by the presence on the board of a much larger number of places for connecting electrode pairs than the EEG recording channels, and, accordingly, connector pins at the ends of the tinsel taps of the cable connecting the device to the electronic amplifier of the brain biocurrents. This makes it possible for the operator to use and connect those electrode pairs that are above the area of the cerebral cortex necessary for the study, ignoring the remaining (not in place) electrodes.

Remaining unconnected electrode sleeves continue, however, to perform the function of mechanical support and stabilize the position of the device installed and fixed on the head.

The proposed drawings and photographs show preferred embodiments of the invention.

Figure 1 schematically shows an electrode board (top view), an ellipsoidal holder plate (1) which has multiple socket holes (2), the edges of which are covered by the upper, extended ends (caps) of the EEG tube electrodes (3). Slots-slots (5) are shown on the edges of the holder plate with a part of the fixing belt (6) fixed in one of them. An aperture (5a) is shown in the back, central part of the plate for fixing an additional fixing braid therein.

Figure 2 shows a side image of the electrode board, due to which the remaining and additional structural elements become visible. In this case, part A of FIG. 2 shows a side view, and part B of FIG. 2 is a sectional side view. The remaining symbols in figure 2 correspond to the symbols in figure 1.

Inside the nesting holes (2) of the holder plate (1) are the tubular electrode housings with caps (3). In the lower part of the electrodes, return springs (4) are fixed by means of a retaining ring (3b) or by soldering their lower turns to the lower surface of the electrode housings (3c). At the edges of the holder plate, an empty slot of a slot (5) is shown (FIG. 2, side A) and a slot of a slot with a fixing strap (6) fixed therein (FIG. 2, part B). On the side B of FIG. 2 also shows a longitudinal section of the housing of a separate electrode (3a) with a plug of a detachable contact (8) connected to it, as well as deformed (compressed), due to mechanical pressure from the side of the scalp surface (7), a return spring (4a ) (side view without section) with the EEG electrode body displaced upward (3).

Photo 1 shows a prototype electrode board, to which a plug-in connector is connected to one of the tubular electrodes. A part of the electrolyte gel is visible, displaced in the form of a drop from the internal cavity (according to the “piston-cylinder” principle) from the side of the lower end of the electrode.

Photo 2 captures the device while recording an 8-channel EEG. The fixation was made using the main locking belt "under the chin." An additional, fixing, elastic cord is not involved due to the calm behavior of the dog.

In photo 3 you can see the device "assembled", immediately before installation and fixation on the head of an average dog with four pairs of EEG electrodes connected. The fixing belt, made in the form of an elastic textile-rubber tape, is clearly visible.

Photo 4 shows an example of using a prototype EEG electrode board designed to work with small animals (in this case, a cat).

Photo 5 shows an alternative way of connecting the electrode board via clamping contacts (crocodile type) for four-channel EEG recording of a large dog.

The prototypes of the claimed device were previously experimentally and practically tested in an electrophysiological laboratory and animal clinic with different sizes and shapes of heads. Positive results were obtained in accordance with the objectives.

Claims (5)

1. A device for installing and fixing EEG electrodes on the head of animals, characterized in that it is made in the form of a single electrode board, consisting of a holder plate with a device for fastening fixing belts and multiple socket holes in its central part, inside which are hollow, tubular, metal movable electrodes, while limiting their free movement relative to the edges of the corresponding socket holes on the outside of the holder plate is provided uktivnym expansion diameter of the electrode body in the area of the detachable connection of the plug contact and the back side - return springs flanking the electrode body, and fixed on their lower bottom turns with the upper turns of the springs abut the bottom surface of the plate-holder. 2. The device according to claim 1, characterized in that the plate-holder of the EEG electrodes is made in the form of a transparent or translucent, durable polymer made of plexiglass elliptical octagonal, round shape, while the external dimensions of the holder plate are commensurate with the dimensions of the upper surface of the scalp of the test animal , and most of its surface contains through round-shaped nesting holes located in a checkerboard pattern, symmetrically, on both sides of its corresponding sagittal line of the skull centrally axis, and the side and rear of the plate-holder equipped with special notches, slots or additional fastening mechanisms with a similar function, which are part of the fastening device. 3. The device according to claim 1, characterized in that the electrodes used in its design are in the form of a hollow, metallic, stainless steel, non-ferrous metal or alloy, including amalgam coatings of a cylinder in the form of a tube, a sleeve with a diameter of 1 to 10 mm with expanded or expanded by fastening the lock ring of the washer, the protrusion of the upper part in the form of a cap, and the outer diameter of the expansion should be slightly larger, and the outer diameter of the electrode tube housing should be, respectively, somewhat smaller than of the nesting hole of the holder plate, while in the lower part of the electrode must be secured by soldering the lower turn, securing the retaining ring, protrusion, washer, a return spring located around the protruding part of the electrode housing from the side of the lower surface of the holder plate, in which it should rest against the upper turns. 4. The device according to claim 1 or 3, characterized in that the electrode board is connected to the electronic equipment by means of the plug-in connectors-contacts located at the ends of the cable wires according to the TOUCH PROOF “socket” principle, with the external diameter of the plug being accordingly smaller than the diameter of the internal cross section of the electrode cavity, to ensure the possibility of its easy connection and subsequent connector, subject to the conditions for ensuring strong electrical contact of their metal surfaces ostey. 5. The device according to claim 1 or 2, characterized in that the fixation of the electrode board mounted on the animal’s head is carried out by means of a fastening device made in the form of a fixing belt in the form of a bundle, elastic, rubber tape, fixed in special slots-slots in the form of holes , additionally mounted fixtures located on the back of the additional and lateral main parts of the holder plate, and the main locking strap is designed to tension and fix the animal "under the chin", and additional th - "for the collar."

Images