ELECTRODE POSITIONING NET FOR NEUROLOGICAL MONITORING BACKGROUND

[0001 ] The positioning of electrodes for neurological monitoring for electrocardiograms (ECG) and electro-encephalograph (EEG) procedures needs to be done precisely. Precise positioning of the electrodes on the head of a patient helps to assure accurate results. However, the sizes and shapes of the heads of patients and the type and amount of hair they have vary from patient to patient. Positioning electrodes precisely is also especially difficult when monitoring is to be performed under emergency conditions, or when speed is critical, or when positioning of the electrodes takes place outside of the controlled environment of hospital.

[0002] Headsets have been developed that fit over the head of a patient and that indicate to the user the correct locations for electrode placement. See for example US publication 2015/001 1857, which is incorporated herein in its entirety by reference. These types of headsets, however, tend to be bulky. Even when using a headset, the process of placing electrodes is not an easy or quick task to do correctly.

[0003] A headset that makes applying the electrodes quicker and more

accurate would be an advantage.

SUMMARY

[0004] The present electrode positioning net is simpler and smaller than prior art headsets and may be used for positioning up to 48 electrodes.

[0005] The electrode positioning net comprises a set of cords interconnecting plural junctions. Each junction may carry an electrode assembly or alternative device for attaching an electrode and which serves as position- identifying location for the electrode. Headsets that carry electrodes, particularly electrodes that are easily attached to the scalp, shorten the time required to prepare a patient for neurological monitoring. [0006] Because of the cords are resilient and are connected the the junctions, the electrode positioning net defines a resilient three-dimensional web of junctions that can be placed on the head of a patient. Resilience of the cords enables the user to adjust the electrode positioning net to the right orientation on any patient's head, and to do so dynamically, regardless of the size or precise shape of the patient's head, because shifting one junction into place automatically alters the tension on the cords that connect that junction to others.

[0007] Electrodes, together with their respective conductors, may be mounted to the junctions of the present electrode positioning net or may be applied to the junctions after applying the electrode positioning net to the head of a patient. Once the electrodes are in position on the patient's head, they may be placed into contact with the patient's scalp and their electrical conductors can be connected to a neurological monitoring device to begin monitoring.

[0008] An aspect of the disclosure is an electrode positioning net that

comprises a plurality of cords and a plurality of junctions. Two junctions are attached to the opposing ends of a cord, thereby interconnecting those two junctions. The interconnection of the junctions by the cords defines a three- dimensional network of junctions and cords. When the network of junctions and cords is fitted to the head of a patient, the tension of each cord adjusts the relative positions of the nearest junctions with respect to each other, without regard for the size or shape of the patient's head, to equalize the tension among the cords. Equalizing the tensions of the plural cords of the electrode positioning net by adjusting the positions of each electrode junctions over the patient's head moves the junctions, and the electrodes, into position. Thus the electrode positioning net tends to self-adjust to equalize tension in the cords and in doing so moves the electrodes into the right relative positions.

[0009] Another aspect of the disclosure is that the cords are made of a

resilient material such as natural or synthetic rubber, which may be covered with a textile sheath surrounding the resilient core. The cords may be less than 2 mm thick so the electrode positioning net is not bulky or resistant to movement. [0010] An aspect of the disclosure is a plurality of electrode assemblies carried by the plurality of junctions of the electrode positioning net. The electrode assemblies include a housing that attached to, or may be integral with, the junctions. The electrode housing may include eyelets for use in attaching the cords.

[001 1 ] An additional aspect of the disclosure is that, when electrode

assemblies are carried by the junctions of an electrode positioning net, and each of the electrode assemblies has an electrical conductor attached, the electrical conductors may be gathered together and their distal ends terminated in a multi-pin connector for convenience in attaching to a neurological monitor.

[0012] Another aspect of the disclosure is that the electrode positioning net may have 21 junctions for 21 electrodes in the 10-20 International Electrode Placement System and that the junctions may include eyelets for use in attaching the cords.

[0013] An aspect of the disclosure is that the electrode positioning net may have a nasion marker and an inion marker to initialize the orientation of electrode positioning net with respect to the nasion and inion of a patient's head.

[0014] These and other features of the electrode positioning net will be readily apparent to those skilled in preparing a patient for neurological monitoring procedures from a careful reading of the following Detailed Description in view of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In the drawings,

[0016] FIG. 1 shows a right side view of the present electrode positioning net deployed on the head of the patient, according to an aspect of the disclosure;

[0017] FIG. 2 shows a front view of the present electrode positioning net deployed on the head of the patient, according to an aspect of the disclosure;

[0018] FIG. 3 shows a top, rear perspective view of the present electrode positioning net deployed on the head of the patient with electrodes attached to the electrode positioning net, according to an aspect of the disclosure; [0019] FIG. 4 shows a left side view of the present electrode positioning net deployed on the head of the patient with electrodes attached to the electrode positioning net, according to an aspect of the disclosure;

[0020] FIG. 5 is a top, left perspective view of an electrode positioning net with fewer electrodes than the electrode positioning net of FIGS. 1 -4, and having the electrical conductors of the electrodes connected to wiring cable leading to a multi-pin connector for connection to a ribbon cable via a pin socket, according to an aspect of the disclosure;

[0021 ] FIG. 6 is a detailed view of a cord showing its interior structure and a loop on one end, according of the present disclosure.

DETAILED DESCRIPTION

[0022] The present electrode positioning net 10, in an aspect of the

disclosure, may be used as a stand-alone apparatus, as seen in FIGS. 1 and 2, to which electrode assemblies 34 are added after electrode positioning net 10 is applied to the head 100 of a patient, or used with electrode assemblies 34 already attached as shown in FIGS 3 and 4. In figures 1 -4, electrode positioning net 10 is configured for twenty-one electrodes, in conformity with the 10-20 International Electrode Placement System. In either aspect of the disclosure, electrode positioning net 10 serves as a template for indicating to a user the placement locations for electrode assemblies onto a head 100 of patient. The electrodes 42 may be incorporated into junctions 26 of the electrode positioning net 10 in advance, perhaps integrally with junctions 26, or attached after electrode positioning net 10 is positioned on head 100.

[0023] Although the relative positions of the twenty-one junctions 26 are

determined by the lengths of cords 18, the orientation of electrode positioning net 10 is accurately obtained by first locating the nasion 50 and the inion 54 of a head 100 as fiducials. Nasion 50 corresponds to the bridge of the patient's nose; inion 54 corresponds to the extreme back of the head 100. The electrode positioning net 10 may incorporate a nasion marker 58 and an inion marker 62. After aligning to the nasion marker 58 to the nasion 50 and the inion marker 62 to the inion 54 of head 100 of the patient, and equalizing the tension among cords 18, junctions 26 will map a set of electrodes 42 to the correct positions on head 100 of the patient. The electrode positioning net 10 may include a chinstrap 14 to help hold the electrode positioning net 10 to head 100.

[0024] Cords 18 connect junctions 26 together. Cords 18 are resilient and terminate in loops 30, which are secured to junctions 26 by clamps 32.

Junctions 26 may have eyelets 22 for receiving cords 18 and allowing the ends of cords 18 to be folded back against cords 18 to form loops 40, which loops 40 are then secured by clamps 32.

[0025] The purpose of the particular neurological monitoring to be done

determines the number of electrodes 42. The number of electrodes 42 determines the number of junctions 26 and the number and lengths of cords 18. Each junction 26 is connected to at least two junctions 26, which means at least two cords 18 are required to connect three junctions. Some junctions may have additional cords connected to them to build the junction network in more than one dimension so it fits to head 100. The more electrodes 42, the more cords 18 that will be needed and the shorter each cord 18 will be as the density of electrodes 42 on the head 100 increases. There may be at least two cords 18 attached to each junction 26. The distance between junctions 26 determines the length of the cord 18 that runs between them, measured from loop 30 to loop 30.

[0026] The thinness of cords 18 minimizes the deployed surface area of

electrode positioning net 10's, which in turn maximizes the surface area of head 100 that can be accessed and makes it easier to manipulate the patient's hair (e.g., hair parting) in order to quickly and effectively attach or adhere electrode 42 at junction 26. Electrode positioning net 10 may be constructed out of cords 18 made of thin resilient core 82, that is, material that has a high elastic modulus such as natural or synthetic rubber. As illustrated in FIG. 6, cords 18 may be encased in a textile sheath 86 so that cord 18 is a millimeter and up to 2 mm in diameter and can slide easily over the surface of head 100. The elastic modulus of cord 18 enable movement and repositioning electrode assemblies 34 easily and holding the repositioned electrodes 42 in place.

[0027] Cords 18 control the relative positions of electrode assembly 34 on head 100. The resiliency of the cords 18 of electrode positioning net 10 helps to relieve strain by urging the electrode assemblies 34 into position. Resiliency reduces unintentional detachment of the electrodes 42 from the scalp. Excess tension on cord 18 attached to a junction 26 on the application of electrode positioning net 10 to head 100 is automatically relieved by other cords 18 that run to the same junction 26. These other cords 18 respond resiliently to equalize the tension among them by small movements of junction 26. In addition, the equalization of the tensions among cords 18 propagates from one cord 18 to the next and around the electrode positioning net 10 until equalized. As the tensions equalize, the lengths of the cords 18 that run to a junction 26 shorten to reduce tension or lengthen to increase tension on junctions 26 in response to higher tension elsewhere, so cords 18 eventually have lengths proportionally longer to their original lengths as tension among the cords 18 around electrode positioning net 10 equalizes. Accordingly, the electrode positioning net 10 accommodates various sizes and shapes of head 100 and appropriately positions electrodes 42.

[0028] A cord 18 is cut longer than the distance between electrodes 42 on electrode positioning net 10, and its ends are then folded to form loops 30, as best seen in FIG. 6, a. Loops 30 are formed in the ends of cords 18 by folding the end of cord 18 back on themselves. Loops 30 may be secured by clamps 32 after the ends of the cords 18 have been inserted into eyelets 22 in the junctions 26. The relative lengths of the cords 18, as measured from one loop 30 to an opposing loop 30 of cord 18, are pre-established based on the number of electrodes 42 that electrode positioning net 10 is designed to support, the locations of the electrodes 42 on electrode positioning net 10, and the distances between the junctions 26 to which it will be connected. Junction 26 is connected by cord 18 to two or more other junctions 26 so that there is dynamic forces on junctions 26 in at least two different directions. A dynamic force means that if a force is exerted on junction 26 in one direction, there is another force on junction 26 moving it in the opposing direction.

[0029] Electrode assemblies 34 on the electrode positioning net 10 may

include junctions 26 with electrodes 42 ready for deployment. Electrode assembly 34 may also include an electrical conductor 46 attached to electrode 42. The first end of each electrical conductor 46 of plural electrical conductors 46 may extend from electrode 42 running from housing 38. The opposing ends of the electrical conductors 46 may be grouped in a wiring harness 70 leading to a pin socket 74. The pin socket may be connected to a ribbon cable with a multi-pin connector 66 for attachment to a neurological monitoring system (not shown). The materials of electrode positioning net 10 may be selected to not significantly affect image quality of diagnostic X-Ray or computer tomographic (CT) medical imaging. For example, the electrode positioning net 10 may be made of materials that are non-ferromagnetic and non-electrically conductive, and are therefore safer to use in a magnetic resonance environment.