WO2014107446A1

WO2014107446A1 - Eeg data collection intrabuccal method and apparatus

Info

Publication number: WO2014107446A1
Application number: PCT/US2013/078443
Authority: WO
Inventors: Mark Steven COHEN
Original assignee: The Regents Of The University Of California
Priority date: 2013-01-04
Filing date: 2013-12-31
Publication date: 2014-07-10

Abstract

An oral appliance containing an electroencephalographic electrode.

Description

PATENT APPLICATION - EEG DATA COLLECTION INTRABUCCAL METHOD

AND APPARATUS

BACKGROUND

Related Applications

[0001] This patent application claims priority to U.S. Provisional Patent Application Serial No. 61/749,003, entitled "EEG Data Collection with Particular Benefits to Dipole Source Localization and to Mesial Temporal Lobe Diseases Method and Apparatus," filed January 4, 2013.

Field of the Invention

[0002] Aspects of the disclosure relate in general to

electroencephalography. Aspects include an intra-oral ("intrabuccal") pickup electrode that results in improved three-dimensional sensitivity to

electroencephalography (EEG) signals.

"Description of the Related Art"

[0003] Electroencephalography is the recording of electrical activity from the scalp. EEG measures voltage fluctuations that result from ionic current flows within the neurons of the brain.

[0004] In clinical contexts, EEG is recorded from multiple electrodes placed on the scalp for periods of minutes to days. Diagnostic applications include analysis of the spectral content of EEG, referring to the common presence of oscillatory signals, as well as observations of brief or extended electrical events that are pathognomonic of certain diseases or of brain and cognitive states.

[0005] In neurology, the main diagnostic application of EEG is in the case of epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. A secondary clinical use of EEG is in the diagnosis of coma, encephalopathies, and brain death. A third clinical use of EEG is for studies of sleep and sleep disorders where recordings are typically done for one full night, sometimes more. EEG has been a first-line method for the diagnosis of tumors, stroke and other focal brain disorders, but this use has decreased with the advent of anatomical imaging techniques with high (< 1 mm) spatial resolution such as magnetic resonance imaging (MRI) and X-ray computed tomography (CT) .

[0006] A crucial use of EEG is in the localization, within the brain, of regions that may initialize the onset of seizures. These irritative, or epileptogenic zones are used as targets for respective surgeries to prevent further seizures.

[0007] EEG is used heavily in brain research applications on normal subjects. It offers unique information on the timing of the brain's responses to inputs, and in response variations associated with processes such as attention and perception.

[0008] Although its spatial resolution is low compared to

tomographic imaging by CT or MRI, EEG continues to be a valuable tool for research and diagnosis, especially when millisecond-range temporal resolution (not possible with CT or MRI) is required. In typical use, the ability of EEG to identify the location at which electrical sources are generated is limited, which limits the utility of the method.

SUMMARY

[0009] Embodiments include an oral appliance containing at least one electroencephalographic electrodes.

[0010] In one embodiment, an oral appliance comprises a rigid support, at least one electroencephalographic electrode, and a wire. The rigid support is configured to be fitted to a roof of a mouth. The at least one electroencephalographic (EEG) electrode is coupled to the rigid support, and configured to detect electrical signals. The wire is connected to the

electroencephalographic electrode, and is configured to conduct the electrical signals.

[001 1] In another embodiment, an oral appliance comprises a flexible adhesive film, at least one electroencephalographic electrode, and a wire. The adhesive film is configured to adhere to a roof of a mouth. The at least one electroencephalographic electrode is coupled to the adhesive film, and is configured to detect electrical signals. The wire is connected to the electroencephalographic electrode, and configured to conduct the electrical signals.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 illustrates an embodiment of a retainer-mounted EEG electrode device.

[0013] FIGS. 2A and 2B illustrate an alternate embodiment of an EEG electrode device incorporated into a flexible adhesive film.

[0014] FIGS. 3A and 3B shows recordings made from the

intrabuccal electrode and includes periods in which the volunteer had his eyes open and when they were closed.

DETAILED DESCRIPTION

[0015] One aspect of the disclosure includes the realization that electroencephalographic (EEG) results from electrical field variations that result from electrical current sources (dipoles) within the brain. These surface potentials may be recorded conveniently by placing electrically conductive electrodes on the scalp and measuring the voltage differences between them. The sensitivity of these recordings decreases with distance from the electrical source within the brain.

[0016] Another aspect of the disclosure includes the understanding that while the scalp potentials are interesting in their own right, it frequently is highly desirable to determine the three-dimensional localization of the brain dipole sources that result in the scalp potentials. For example, in clinical evaluation of seizure disorders (epilepsy), the diagnostic team generally desires this information, as it can be used to help in planning for surgeries to remove diseased tissues. Such three dimensional localizations are of major interest to brain mapping researchers who seek to associate brain function with specific neural locations. [0017] Unfortunately, the problem of identifying the sources from distributions on the scalp is fundamentally under constrained, because an arbitrary topology of scalp potentials may result from an infinite number of different distributions of dipole sources within the head. Generally, the community resolves this problem by constraining the possible dipole solutions to physiologically plausible locations, and by measuring the surface potentials with very dense recording arrays (many electrodes). Such tools are becoming accepted increasingly as the quality of the constraint methods improves steadily.

[0018] The geometry of the head creates further limitations. The scalp electrodes cannot cover the surface of the head completely or uniformly, because the neck and body prevent the placement of electrodes below the brain. For practical purposes electrodes can be placed on only about half of the spherical surface that surrounds the brain. The lack of three-dimensional coverage introduces additional ambiguity into the localization of the brain sources that create the EEG. Some investigators have advocated the uses of nasopharyngeal electrodes that are literally threaded into the nose, but most volunteers and many patients find this unacceptable.

[0019] The embodiments disclosed here resolve this problem in a straightforward manner by fitting a device into the mouth of the subject, and to the interior surfaces of the teeth, thereby allowing additional electrodes to be placed immediately below the brain. This location is ideal in many respects. Not only is it approximately in the center of the least covered region of the head, but it is near to the mesial temporal lobes, which are the site of the epileptogenic tissue in a large fraction of seizure patients. It is also close to important brain structures such as the thalamus, brain stem and orbitofrontal cortex that are difficult to study by EEG. Palate locations have been tried sporadically in the past, but have been subject to many problems: The electrodes themselves must be adhered in some manner to the roof of the mouth, which creates irritation and discomfort (and evokes a strong gag reflex). Movement of the tongue, especially contact by the tongue, creates large electrical disturbances in the EEG record; sterility of such devices creates special concerns and the conductive properties of saliva make it difficult to create a small point contact as needed for good EEG localization.

[0020] FIG. 1 illustrates an embodiment of a retainer-mounted EEG electrode device, constructed and operative in accordance with an embodiment of the present disclosure. As shown in FIG. 1, in one embodiment, an

appliance 1000 similar to a dental retainer, includes a support 5, and one or more small wells carved into the appliance 1000; the wells receive an EEG electrode 2. As shown in this embodiment, contacts sit in wells set into support 5. Electrical leads (wires) 3 are carried to the front or side of the appliance 1000 and exit between the lips. As illustrated in FIG. 1, appliance 1000 has a four lead configuration, but other embodiments may be made with any number of leads.

[0021] In some embodiments, electrodes 2 may be made of thin films of silver, silver-chloride, or the like. Electrical leads 3 may be made of flexible copper wires or other electrical conducting material known in the art.

[0022] Other than the electrodes 2 themselves, the top surface of the appliance may be covered in absorbent material (such as paper, chamois, or sponge dams) in such a manner that when the appliance 1000 is put in place, the surface of the palate is dried, improving the contact specificity. The support 5 may be made of an insulating material, such as plastic resin, dental wax, or other material that may be used and placed into the mouth of a patient in dental appliances. In one embodiment, the appliance 1000 would be fitted to the individual subject in the same manner as dental retainers, by creating a mold and then casting the thermoplastic resin to it. This is an inexpensive and easy process, and the mold is adapted to include the wells that will receive the electrodes 2. The bottom surface of the appliance 1000 is made smooth and such devices are easily tolerated by people.

[0023] FIGS. 2A-2B illustrate an alternate embodiment of an appliance 2000, constructed and operative in accordance with an embodiment of the present disclosure. FIG. 2A illustrates the appliance 2000 assembled, while FIG. 2B illustrates the appliance 2000 in an exploded view. In this embodiment, an intrabuccal appliance 2000 includes electrodes 2 placed on a flexible adhesive surface 4 and separated by flexible non-conductive material 1. Signals are conveyed from the appliance 2000 via flexible wires 3. The adhesive surface, wires 3, electrodes 2, and flexible non-conductive material 1 are layered together in a thin "sandwich" configuration, exposing the adhesive materials 1 and the electrodes 2 to the upper surface.

[0024] In an alternative embodiment, support 4 would use a soft flexible material (such as silastic or rubber), which could be reusable after cleaning and sterilization. In such embodiments, the appliance 1000 may be similar to the devices used by hockey and football players to prevent jaw injuries, or by people during sleep to prevent grinding of the teeth. Small diameter wires 3 carry the EEG signal out of the mouth, as these are more easily tolerated, even for long periods, such as for sleep studies.

[0025] In yet another embodiment, the electrodes 2 are placed onto an adhesive tape or film material that adheres lightly to the roof of the mouth. This configuration may be made very thin to minimize discomfort to the patient or subject. In any of the aforementioned embodiments, non-conductive barriers may be added, if desired to isolate the electrode contacts from each other.

[0026] FIGS. 3A and 3B shows recordings made from the

intrabuccal electrode and includes periods in which the volunteer had his eyes open (FIG. 3A) and when they were closed (FIG. 3B), constructed and operative in accordance with an embodiment of the present disclosure. As shown in FIGS. 3A and 3B, clearly visible is an increase in signal energy in both the "alpha" (8- 14 Hz) and "beta" (14-30Hz) bands. This demonstrates that the intrabuccal electrode appliance 1000 and 2000 are able to detect brain electrical signals without introducing additional artifacts.

[0027] The previous description of the embodiments is provided to enable any person skilled in the art to practice the disclosure. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Thus, the present disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

WHAT IS CLAIMED IS:

1. An oral appliance comprising: a rigid support configured to be fitted to a roof of a mouth; at least one electroencephalographic (EEG) electrode, coupled to the rigid support, configured to detect electrical signals; and a wire, connected to the electroencephalographic electrode, configured to conduct the electrical signals.

2. The oral appliance of claim 1 wherein the rigid support is cast from plastic resin material.

3. The oral appliance of claim 2 wherein the rigid support is configured to be fitted next to interior surfaces of teeth within the mouth.

4. The oral appliance of claim 3 wherein the electroencephalographic electrode is made of a thin film.

5. The oral appliance of claim 4 wherein the thin film contains silver or silver-chloride.

6. The oral appliance of claim 4 wherein the wire is made of copper.

7. An oral appliance comprising: a flexible adhesive film configured to adhere to a roof of a mouth; at least one electroencephalographic (EEG) electrode, coupled to the flexible adhesive film, configured to detect electrical signals; and a wire, connected to the electroencephalographic electrode, configured to conduct the electrical signals.

8. The oral appliance of claim 7 wherein the electroencephalographic electrode is made of a thin film.

9. The oral appliance of claim 8 wherein the thin film contains silver or silver-chloride.

10. The oral appliance of claim 8 wherein the wire is made of copper.