Andrew G. Brucks, M.S.
Pain Evaluation and Intervention Program Department of Veterans Affairs Medical Center and Medical College of Georgia Augusta, Georgia
Headache is the most common pain complaint(11) and the most frequent medical problem seen in medical clinics(7). Most experts(3) believe that the majority of headaches are muscle tension-type. Community-based epidemiological studies have found that 14% of men and 29% of women have had headaches either every few days or headaches which significantly bothered them(9).
Tension headache is generally described as a bilateral dull ache, pressure or cap-like pain that is usually located in the forehead, neck and shoulder regions. The headache typically occurs from two to seven days a week and can last from one hour to all day; a small proportion of tension headache sufferers have continuous headache. Migraine headache, on the other hand, is described as a unilateral pain, generally accompanied with nausea and vomiting, with the pain characterized as throbbing or pulsating. Clinicians who deal with headache patients should use a standardized set of inclusion and exclusion criteria for diagnosis such as specified by the Ad Hoc Committee on the Classification of Headache(1) or the newer Ad Hoc Committee of the International Headache Society(2).
Treatment of Chronic Tension Headache
Behavioral treatments for chronic tension headache have been found to be as effective as pharmacological interventions(8). Although nearly all of the headache literature treats biofeedback and relaxation therapy as separate interventions, most clinicians combine both procedures when treating their tension headache patients.
A study by Holroyd and his colleagues(10), detected no significant difference between subjects who trained to increase or decrease their muscle tension levels; high success feedback groups showed substantially greater improvements in headache activity (53%) than low success groups (26%). This study demonstrated the importance that cognitive mediating factors such as perceived success and self efficacy play in biofeedback training, and the enhanced awareness of ones level of muscle tension during non-biofeedback periods. Thus, the emphasis on biofeedback training with tension headache should focus on skill acquisition and the therapist-patient relationship.
EMG Biofeedback Training
Initially, place the two active sensors approximately in the center of the forehead in line with the pupil of the respective eye. The reference (ground) sensor is placed between the two active sensors (figure 1). We recommend the use of disposable EMG sensors to insure against infection. A reading of less than 2 microvolts generally indicates a fairly relaxed muscle group. If the level starts off and remains low even during stress provoking imagery or discussion, or after the patient has gone through an adequate course of forehead EMG biofeedback and little change in headache activity is noted, advance to the shoulder and neck regions (figure 2). Palpation for muscular tenderness may also be used in the selection of electrode placement sights.
To decrease patient anxiety, refer to the electrodes as sensors, and indicate that EMG only senses electrical activity and does not send current through the body.Settings on the MyoTrac(TM):
Initial Session Strategies
We say something like this: "Its traditionally been assumed that the type of headache you have - tension headache - is caused by very high levels of muscle tension in your forehead, neck and shoulder areas. These muscles have been tense for a long time. Through biofeedback training, you will learn to both be aware of and decrease your muscle tension levels at any time. When you do this, its hoped that you will get a decrease in your headaches."
We next give the patient a number of possible strategies to choose from. We emphasize that learning the biofeedback response is purely an idiosyncratic process and that what works for others may not work for them. We customarily describe 6 possible biofeedback strategies outlined in Table 1 (figure 3).
In the first session, we usually tell the patient to pick only one strategy and stick with it the entire session. We keep the initial session short - a 3-5 min. adaptation period (Just sit quietly with your eyes closed) and a maximum of 12 min. of biofeedback. (In latter sessions, we increase the biofeedback portion to a maximum of 25 min.) We emphasize that learning to relax muscles at will can be a difficult response to learn and that it may take some time before they can lower their forehead muscle tension reliably; we tell them not to get discouraged if they cannot control their EMG levels immediately. We instruct the patients to let the response occur rather than make it occur, to be passive rather than try to force their forehead muscles to relax. We let them choose which type of visual and auditory feedback they like. At the end of the biofeedback session when the sensors are removed and the sessions data is saved, we inquire as to which strategy was employed and the patients perception as to how effective it was. We also get a self report of relaxation, muscle tension and pain levels on a 1-10 scale prior to and following the session. If using a computer, we review the actual minute by minute printout of the data with the patient. Throughout this review we attempt to impart to the patient the most positive feeling of success gained, based on the realities of the sessions data. The number of sessions may run from 10 to as many as 24.
Coaching and Therapist Attitude
The first, and most important thing for a therapist to determine about coaching, is whether a patient wants and could benefit from coaching. This is truly idiosyncratic. There are three general situations during EMG biofeedback that you have to be prepared for:
Situation 1 - The patient has decreased forehead muscle tension levels. Possible responses are:
a) Thats fantastic! Keep up the good work. I want you to remember what you are doing now so you can tell me at the end of the session. Real good! Try to get it even lower. Situation 2 - The patient has not been able to decrease forehead muscle tension levels. Possible responses are: Thats OK. Its as important to find out what makes it go up as it is to find out what makes it go down. I want you to remember what youre doing now so you can tell me at the end of the session. Thats OK. You can only go up so far before you have to start going down. You seem to be going up; you might want to switch to a different strategy. Situation 3 - The patient seems frustrated or appears to be trying too hard. Possible responses are: Thats to be expected. Remember, I told you that this is a very difficult response to get. If it was easy, you wouldnt need me or the machines. Lets take a break. Sometimes all you need is a few minutes to clear your mind and then you come back like gangbusters. You may want to think of yourself as a scientist, who dispassionately tests theories and tosses them in or out depending on whether or not they work. As a rule, we would suggest that coaching be done in a limited basis, as this will help to generalize the response to the real world, for in everyday situations patients do not have a therapist accompanying them. It is imperative for the therapist to convey as enthusiastically as possible to the patient that he or she is doing well in the biofeedback session.
Home practice has traditionally been considered an essential aspect of all psychophysiological interventions for chronic tension headache(8,12). Home practice can be conducted in many ways: The simplest form of homework is to instruct the patient to practice the office strategy that seemed to work the best at home and in other real world locations such as the job, supermarket, etc. (we usually instruct them to do so at least four times a day). The use of a home practice EMG unit, such as the MyoTrac(TM), is also quite helpful. An important application for the MyoTrac(TM) EMG is to use it in situations which generally initiate headaches. For example, computer operators might monitor muscle activity while typing, using the delayed threshold function (internal switch positions at OFF/ON/ABV/WIDE) which provides a tonal warning only when the threshold level has been exceeded for more than 4 seconds. In this way, maintained muscle tension is minimized, while appropriate low levels of muscle activity is reinforced.
Generalization involves preparing the patient to carry the learning that may have occurred during the biofeedback session into the real world. The most common method, by far, is a self control condition which is interspersed between a baseline and a feedback condition. The self control condition involves asking the patient to control the desired psychophysiological response (e.g. "Please try to lower your forehead muscle tension") without any feedback. If the patient can control the response, the clinician may assume that there has been between-session learning (i.e. generalization). Another method of testing for generalization is to present a pre- and post-treatment stressor to the patient and, if there is less arousal during and after a stressor in the post treatment, the clinician may infer that generalization has occurred. A third way of preparing the patient to generalize the biofeedback response is to try to make the office biofeedback training as close to real world situations as possible, such as switching to an uncomfortable chair or standing during the session.
Biofeedback for tension headache in the elderly
Based upon the research (4,5,6) and our clinical experience we would suggest the following when working with the elderly tension headache patient: First, to be certain that the patient understands the therapists instructions, we would suggest requesting each patient to verbally repeat each sessions instructions. Second, therapists should talk at a somewhat slower rate than usual to insure that rationale and instructions are comprehended. Third, the therapist should make every attempt to simplify the instructions and, especially, to avoid the use of sophisticated language or jargon. Fourth, a brief summary of previously imparted information should be given at subsequent sessions to aid patients in retaining details. Fifth, turn up the biofeedback auditory feedback volume to ensure the patient can hear it, or use an earphone. We would also suggest moving the visual feedback monitor closer to ensure that the patient does not have to strain to see it. Finally, be patient with the elderly headache sufferer. Spend some extra time listening; do not communicate a desire to hurry the session. Schedule appointments for 10 minutes longer than usual.
A biofeedback - behavioral program to assist headache patients to decrease both the severity and frequency of headaches has been described. The program includes in-clinic training as well as the inclusion of EMG portable home trainers to provide reinforcement of behavioral and muscle control strategies in the real world.
1. Ad Hoc Committee of the International Headache Society. Classification of headache. Journal of American Medical Association, 179, 717-718, 1988.
2. Ad Hoc Committee on the Classification of Headache. Classification of headache. Journal of the American Medical Association, 179, 127-128, 1962.
3. Andrasik, F. & Blanchard, E.B. Biofeedback treatment of muscle contraction headache. In Hatch, J.P. Fisher, J.G. Rugh, J.D. (eds.) Biofeedback: Studies in Clinical Efficacy. NY: Plenum Press, 1987.
4. Arena, J.G. Hannah, S.L. Bruno, G.M. & Meador, K.J. Electromyographic biofeedback training for tension headache in the elderly: A prospective study. Biofeedback and Self-Regulation, 4, 379-390, 1991.
5. Arena, J.G. Hannah, S.L. Bruno, G.M. Smith, J.D. & Meador, K.J. Effect of movement and position on muscle activity in tension headache sufferers during and between headaches. Journal of Psychosomatic Research, 35, 187-195, 1991.
6. Arena, J.G. Hightower, N.E. & Chang, G.C. Relaxation therapy for tension headache in the elderly: A prospective study. Psychology and Aging, 3, 96-98, 1988.
7. Bakal, D.A. Psychology and Health, Second Edition, Springer Publishing Company, New York, 1992.
8. Blanchard, E.B. Psychological Treatment of Benign Headache Disorders. Journal of Consulting and Clinical Psychology, Vol. 60, No. 4, 537-551, 1992.
9. Dupuy, H.J. Engel, A. Devine, B.K. Scanlon, J. Querec, L. Selected Symptoms of Psychological Stress, US Public Health Service Publication #1000, Series 11, #37. National Center for Health Statistics. 1977.
10. Holroyd, K.A. Penzien, D.B. Hursey, K.G. Tobin, D.L. Rogers, L. Holm, J.E. Marcille, P.J. Hall, J.R. & Chila, A.G. Change Mechanisms in EMG Biofeedback Training: Cognitive Changes Underlying Improvements in Tension Headache. Journal of Consulting and Clinical Psychology, Volume 52, 1039-1053, 1984.
11. Peatfield, R. Headache. New York, Springer, 1986.
12. Schwartz, M.S. Biofeedback: A Practitioners Guide. New York: Guiliford Press, 1987.
Neurobit Optima distinguishes, among other things, by multimodal measurement channels. which functions can be individually selected by a user.Product highlights
Neurobit Optima works with several software applications enabling flexible data processing and storage, audio and visual presentation of feedback signals (graphs, animations, DVD films, games etc.):
BioExplorer - popular, feature-rich biofeedback software with visual designs of data processing and presentation.
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Mind-Body Training Tools - multimodal biofeedback package for peak performance training
BrainBay - free biofeedback software for personal use
eBioo - neurofeedback software for business and other trainingWarranty
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IMPORTANT NOTE. This equipment is not a medical product. It is intended for psychological training by neurofeedback & biofeedback, research and technology purposes.
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Zukor's Grind is a next-generation feedback game for use in neurofeedback and biofeedback designed by professional game developers under the guidance of clinical practitioners. Zukor’s Grind benefits neurofeedback and biofeedback clinicians by giving them an unprecedented level of control of the patient feedback experience to increase both efficacy and patient retention. Zukor's Grind’s youth-oriented graphics and skateboarding theme are perfect for use with teens, pre-teens and young adults, or anyone that is young at heart.
Zukor's Carnival is not a single game, but rather ten games in one. The games are based upon the simple, classic games featured in carnivals, state fairs and amusement parks. Since carnival games are familiar across all age groups and cultures, Zukor’s Carnival has a broad appeal that makes it useful for all ages of men, women and children around the world.
Zukor’s Sports 1 is a clinical and peak performance feedback game which includes 10 popular mainstream sports games. It uses simple gameplay action focused on “accuracy” with a central visual focus. The following sports games are included: Baseball Pitching, Baseball Batting, Basketball Free Throw, Basketball 3-Point, Football Passing, and much more.
Zukor's Drive is an advanced feedback game which offers gameplay from very relaxed to extremely intense, or any point in between. It is designed for clinical neurofeedback or biofeedback training and, with an upgrade, for peak performance training. Zukor's Drive standard "Clinical Version” offers a solo or dual drive modes, plus an unique doppelgänger option in which the patient competes against their own past performance. It includes 15 diverse vehicles and 5 high-quality tracks.
Zukor's Air is a flying-themed feedback game featuring airplanes (modern and historic), animals (parrot, bat, bald eagle, etc.), insects (butterfly, bumble bee, etc.), dragons, a flying pink pig and more. Zukor's Air will appeal to patients of all ages, including young children, girls, boys, teenagers and adults. The goal of Zukor's Air is to fly across the Pacific ocean, from San Francisco to Japan, and along the way to fly through rings in the air for points. Zukor's Air is optimized for clinical neurofeedback and biofeedback, which means it has a gameplay dynamic that emphasizes relaxed focus.
The CIS works with the BrainMaster software to provide 3D visualization capabilities and other human-to-computer interfacing possibilities. Suites of 3D display screens - called "feedback interfaces" - provide quality training experiences by presenting incoming streams of physiological data in pleasing and intuitive to use forms.
The NEW 3D Add-on Neurofeedback game is pure feedback. Distinct rewards and inhibits change ship speed, level visibility and music volume immediately and clearly. Real 3D graphics, 20 unique levels. Responsive background music and optional joystick control keep your clients focused and compliant .
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Add-on Neurofeedback tool. 2000 Objects, 138 Backgrounds, 79 Particle Types, 26 Feedback Types, 20 Preset Mini Games, Infinite Possibilities. These are not video clips. The graphics of these mini games are created by Particle Editor in response to bio/neurological changes. Load any of the 20+ included systems and enjoy the original music and full color, full motion feedback of Particle Editor where flowers, fish and beautiful abstract graphics are the feedback.
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Biofeedback for ADHD
Using biofeedback (also called neurofeedback or neurotherapy) to treat my daughter Natalie's attention deficit hyperactivity disorder (ADD/ADHD) and comorbid conditions has my insides aching with hope for a significant, lasting improvement in her symptoms. I often feel as if I'm about to cry. Why is something as wonderful as hope so terribly painful?
Some time ago I wrote about Katherine Ellison’s book Buzz: A Year of Paying Attention . which chronicles Ellison's quest to treat her and her son's attention deficit hyperactivity disorder (ADD/ADHD). After reading it, I considered having my daughter, Natalie, try neurofeedback training, an alternative ADD/ADHD treatment that is also sometimes referred to as biofeedback or neurotherapy. which is aimed at training the brain to reduce impulsivity and increase focus. It’s one of several approaches to managing ADD/ADHD that Ellison, an adult with ADD/ADHD. describes exploring for herself and her son, Buzz, who also has ADD/ADHD, in the book. My interest piqued, I researched neurofeedback online and read a book about it from the library. Then I ran the idea by Natalie’s psychologist, Dr. Phillips.
He didn’t say we shouldn’t try it. He didn’t say it couldn’t work. He said that in the years he’s been practicing, he’s seen many parents become excited about various ADD/ADHD treatments or strategies that they hear about. They invest a lot of money, time, and emotional energy in their latest discovery in hopes that it will help their child. When it doesn’t, he ends up guiding those parents through the grief process around accepting a child’s disability all over again. Whether or not we tried neurofeedback was up to me, of course, but I’d risk re-experiencing that grief if the treatment didn’t yield an improvement. After some thought, I decided to halt my research, and I shelved the idea of biofeedback.
But recently, we had an appointment with Dr. Phillips, and he brought the topic of neurofeedback up again. He’s had three clients initiate neurofeedback training with a particular practitioner, and all three appear to be enjoying some benefits. He suggested I consider meeting with the practitioner, just to learn more.
I did not consider meeting with her just to learn more. No, I jumped right in and scheduled an appointment to get Natalie started!
I tried -- really tried -- to go into this experiment with realistic expectations, to stay neutral about whether or not there’s anything to it, or, if not neutral, to err on the side of wariness rather than hope. But we’re talking about my daughter’s life here. I couldn’t help but become emotionally invested.
Our first appointment was for an evaluation. The practitioner, Ladelle Lybarger, is a retired nurse who works out of her home office in Des Moines, Iowa. She put Natalie and me at ease immediately with her quiet, gentle demeanor. Explaining every movement, she cleaned off two small spots on Natalie’s scalp and stuck electrodes to the spots with a little conductive gel and also clipped one to Natalie’s ear. After a few keyboard strokes on a laptop set off to the side, an EEG readout began to run across a computer monitor that faced Natalie’s chair. Three separate lines appeared, representing different types of brain waves. Lybarger repeated this a few times, moving the electrodes to different locations on Nat’s scalp. She printed out hard copies of the readouts, on which she identified specific patterns in the waves. It was fascinating to get a visual showing how certain brain waves were too slow, causing inattention. Another type of wave showed sudden large bursts of energy, indicating that another part of Nat’s brain was working hard to compensate for the inattention. This, the nurse said, explained why Natalie has trouble sleeping. Even as she tries to slow down to prepare for sleep, those bursts of energy continue, trying hard to keep her brain awake and alert. The first goal of the neurofeedback training would be to train the “sleepy” waves to maintain a more effective level. In other words, Lybarger had identified problems that she knows how to work with. She believes she can help. We agreed to begin once-a-week treatments. (More on those in future posts!)
Before we left that first appointment, Lybarger offered to lend me the book A Symphony in the Brain: The Evolution of the New Brain Wave Biofeedback by Jim Robbins. I accepted it eagerly, and for the next week, I immersed myself in learning more about biofeedback. I learned it could help with a variety of problems, from migraine headaches to severe brain injuries. For kids like Natalie, if it works, it could improve virtually all the symptoms of ADD/ADHD -- inattention, sleep issues, regulation of emotions, impulsivity -- noninvasively, safely, and with long-term effects -- the stuff of miracles to parents like me. My hopes rose like a hot air balloon in the summer sky.
Then I’d read something else, and it would blow holes in that hope, on an online forum where the majority of participants reported no effect from their forays into neurofeedback and in a book about ADHD that reported that while there is some research that suggests neurofeedback may help, none suggests it can replace medication -- something I had begun to hope was possible. Then I read another pro-neurofeedback book -- Healing Young Brains: The Neurofeedback Solution. by Robert W. Hill, Ph.D. and Eduardo Castro, M.D. on my Kindle, and its contents were as positive as the loaded words in its title. Up my hopes rose.
I told Nat’s psychiatrist, Dr. Mishra, that we were going to start neurofeedback training. “The research doesn’t support it,” she responded, simply and directly. I shrugged. We’re going to do it anyway. I thought to myself, but her words often echo in my mind.
On our next visit to Dr. Phillips, I updated him on our first three neurofeedback sessions. I confessed that I had let my hopes rise. For two days after session number two, Natalie was unusually calm, almost sleepy. I wanted to attribute that effect to the neurofeedback, but I know it could be totally unrelated. He tried to tether my hopes -- to ground me in reality. I know, I know! I thought as he told me to think of this as just one more tool among many, just one piece of an overall treatment plan. That’s just what I’d tell you, I thought as he spoke, if I were the therapist and you were the client’s parent. But I want to believe in neurofeedback, and its potential to help my daughter, so badly!
The emotional ups and downs have left me depressed, exhausted. Why did I get my hopes up? On the other hand, why shouldn’t we give bioback a try? I don’t know what the future holds. All I know is that even as my brain says use caution, my tender heart flies.
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From Wild Divine Inc.: Zen Journey by Wild DivineNote: This program is designed for use with the IomBlue biofeedback sensor from Wild Divine, however, complete game CAN be experienced without IomBlue.Zen Journey: The Secrets of Zen with Zen Master Nissim AmonAuthentic ZenA Zen Journey is authentic Zen training with a real Zen Master. You're not going to be able to just listen and be passive. The IomBlue will detect the quality of your meditations, and you won't advance until the Zen Master is satisfied you are making suitable progress towards the next robe. (Includes Extra Easy setting for beginners)Exciting new "Intelligent Guide" in Zen Journey Unique to Zen Journey is the "Intelligent Guide". During key meditation sessions guided by Master Amon, your IomBlue will detect whether your mind is wandering or distracted from the teaching, and this will trigger the Master to give you helpful guidance. If you are doing well, the Master may reward you with positive feedback.The Zen Journey Experience- Guided Meditations with the Zen Master- The Zen Master's riveting 5-part story of Buddha- Zen stories reinforce the teachings & training- When ready, the Master delivers your "Robe Talk"- Highly customizable, Infinitely replay-able- A rich, rewarding, authentic Zen experienceZen Journey Detail- White, Brown, Blue, Purple, Black robes to earn- Night Talk" with the Master in the Zen Garden- For Beginners & Experts: Choose your settings- Zen anywhere: Home, office, hotel, on a flight- Includes full version of "Progressive Scan Meditation"Zen Journey is simple and easy to use1. Attach your IomBlue ear clip2. Start the Zen Journey app3. Zen Journey will automatically connect to your IomBlue!Wild Divine's IomBlue: Observing Mind & BodyWhether you are stressed or calm, tense or relaxed, in a deep meditative state or wrestling with busy brain, your body produces subtle signals like changes in heart rate, heart rate variability, breathing, sweat gland activity, and skin temperature.The Iom Mind-Body sensor, based on the science of biofeedback, detects key mind and body signals via ear clip, and delivers this information to Wild Divine Apps on your iOS device.iOS Device & IomBlue Compatibility:iPad: 3rd generation, 4th Gen, iPad Air, iPad Air 2, iPad Mini and neweriPhone: 4s, 5, 5c, 5s, 6, 6 Plus and neweriPod Touch: 5th Generation and newerNote: You do not need to "pair" the device, just turn on the IomBlue, and run the app. There is ZERO setup required.Available Wild Divine iOS apps for IomBlue: (Search for Wild Divine in App Store)1. Progressive Scan Meditation2. Relaxing Rhythms 15-Step Mind Body Mastery program3. Zen Journey with Zen Master Nissim Amon4. Mindfulness Meditation with Tara Brach, PhD5. Villa SerenaGuidance from the Masters: Using the IomBlue & Wild Divine apps created with talented leaders and teachers such as Dr. Andrew Weil, Dr. Dean Ornish, Tara Brach PhD, Zen Master Nissim Amon and others, you receive instant, personalized feedback on the quality and depth of your meditation, relaxation, and mindfulness practice, saving weeks, months or years versus the old "trial and error" method. No more closing your eyes and wondering "Am I doing it right?"Each Wild Divine program uses your mind and body Iom signals in a unique and different way. While both Zen and Mindfulness are highly effective, Zen takes a different approach than Mindfulness. Explore and celebrate the positive effects of the various practices. Find the combination best for YOU.Books, dvd's, audio courses are created for one average, generic person. You are unique. With the personalized, real time feedback of the Iom, a custom experience is created for YOU.
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Bruxism biofeedback apparatus and method including acoustic transducer coupled closely to user's head bones
US 6270466 B1
A method and apparatus for the treatment of bruxism thorough biofeedback is disclosed. In one embodiment, the apparatus consists of electronics mounted in a light-weight headband which may be worn comfortably by a user during sleep or while awake. Electrodes within the headband pick up surface EMG voltage signals indicative of bruxism, and bio-feedback is provided to the user by a piezoelectric transducer in mechanical contact with the head of the user. One electrode of the piezoelectric transducer also serves as the reference sense electrode. The electrodes require no chemistry, allowing the apparatus to be worn for considerable periods without skin irritation. Information detailing the timing, quantity, and duration of bruxing events may be stored internally for later retrieval via display, computer interface, or voice synthesis interface. When EMG signals satisfy certain pre-determined time and amplitude conditions, an acoustical bio-feedback signal is generated. The bio-feedback signal may start small and build up until the cessation of bruxing, when it may be rapidly terminated, facilitating treatment without waking a sleeping user.
Having described the invention, what is claimed is:
1. An apparatus for sensing the occurrence of bruxism by a human user and signaling said user by acoustically coupling to said user's head, said apparatus comprising:
a. a plurality of electrically conductive electrodes;
b. means for pressing said plurality of electrodes against the external body skin of said user by positive pressure at a location on said user's body where said electrodes receive low-voltage muscle signals generated by bruxism muscles of said user that are active during the occurrence of bruxism;
c. sense/amplification means for sensing the differential voltage between at least two of said electrodes and selectively amplifying the electrical signals generated by bruxism muscles, such signals termed “bruxism activity signals”;
d. a detector that generates a bruxism event signal when said bruxism activity signal satisfies pre-determined time and amplitude conditions; and
e. acoustical output means for mechanically coupling an audio-band vibrational output signal that corresponds to said bruxism event signal to said user's head.
2. The apparatus of claim 1. wherein said acoustical output means comprises a piezoelectric transducer.
3. The apparatus of claim 1. wherein said plurality of electrodes comprises one reference electrode and two measurement electrodes.
4. The apparatus of claim 3. wherein said acoustical output means comprises a piezoelectric transducer.
5. The apparatus of claim 4. wherein one electrode of said piezoelectric transducer comprises said reference electrode.
6. The apparatus of claim 1. wherein at least one of said electrically conductive electrodes comprises a substantially flat conductive rubber pad attached to a substantially flexible band disposed circumferentially around the users head.
7. The apparatus of claim 5. wherein at least one of said electrically conductive electrodes comprises a substantially flat conductive rubber pad attached to a substantially flexible band disposed circumferentially around the user's head.
8. A method for treatment of bruxism through acoustical bio-feedback mechanically coupled to the head of a human user, said method comprising:
a. picking up surface EMG signals from bruxing muscles through electrodes held in contact with the skin near said bruxing muscles;
b. selectively amplifying said EMG signals in a frequency band where said signals are strongest, while substantially attenuating 60 Hz signals in comparison to said selective amplification;
c. subjecting said amplified signals to decision-making criteria based on time and amplitude, to distinguish events defined by said criteria as “bruxing events”;
d. mechanically coupling, at a first output level of intensity, an audio-band acoustical bio-feedback signal to the head of said user in response to said bruxing events.
9. The method of claim 8 wherein said first output level of intensity is a low output level of intensity, further comprising:
a. increasing said output level of intensity of said bio-feedback signal over time until either a maximum is reached, or cessation of bruxing is detected; and
b. rapidly terminating said bio-feedback signal in response to cessation of said bruxing signal.
This is the U.S. National Phase of application No. PCT/US98/00692, filed under the Patent Cooperation Treaty on Jan. 14, 1998, which claims priority from U.S. provisional application 60/035,536, filed Jan. 16, 1997. This also is a continuation-in-part of U.S. Ser. No. 09/194,237 filing date Nov. 23, 1998 now U.S. Pat. No. 6,117,092 which is the U.S. National Phase of application No. PCT/US97/08641, filed under the Patent Cooperation Treaty on May 21, 1997, which claims priority from U.S. provisional application 60/018,316, filed May 24, 1996.
The invention relates generally to the fields of electromyographic monitoring and biofeedback, and more specifically to biofeedback devices and techniques for treating bruxism.
Bruxism has generally been defined as the nonfunctional clenching, grinding, gritting, gnashing, and/or clicking of the teeth. Bruxism can occur while a person is awake or asleep. When the phenomenon occurs during sleep, it is called nocturnal bruxism. Even when it occurs during waking hours, the bruxer is often not conscious of the activity. Biting force exerted during bruxism often significantly exceeds peak biting force exerted during normal chewing. Biting forces exceeding 700 pounds have been measured during bruxing events. Chronic bruxism may result in musculoskeletal pain, headaches, and damage to the teeth and/or the temporomandibular joint.
The primary treatment for nocturnal bruxism is the use of intra-oral occlusal splints or “mouth guards,” which are generally semi-rigid plastic covers for the upper or lower teeth. Occlusal splints are generally fabricated for a specific individual from an impression taken of the individual's teeth. While some studies have shown that the wearing of an occlusal splint may reduce bruxing event duration and intensity, the large replacement market for “chewed up” occlusal splints attests to the role of the splint primarily to protect teeth from damage, rather than as a cure for bruxism. Even as a symptomatic treatment, occlusal splints often only protect the teeth themselves, while the user may still suffer musculoskeletal pain and possible damage to the temporomandibular joint.
Occlusal splints present numerous inconveniences to the user. They require frequent cleaning, they are difficult to clean, they require periodic replacement, they inhibit speech, and they are frequently lost. For couples sleeping together, occlusal splints are far from “romantic.” Some users perceive that occlusal splints accelerate tooth decay.
Dental researchers and clinicians have made several attempts to address the underlying causes of bruxism through biofeedback. Most commonly, an electromyograph was used to sense the action of the masseter muscle. When muscle activity was detected, an audible tone was generated. This tone alerted the individual that he or she was bruxing. The intention of this biofeedback approach was that a relatively short period of treatment would result in the long-term elimination of the bruxing behavior. Most of the shorter studies indicated that bruxism resumed once the treatment was discontinued. One longer study offered some evidence of sustained reduction in bruxism with longer term use and decreasing frequency of use of the biofeedback apparatus. Because these previous attempts to use biofeedback devices involved bulky electronics and required electrodes to be attached adhesively to the face, they were impractical for long-term use in treating bruxism, and not well suited for consumer use.
Some variations on this biofeedback approach known in the art incorporate sensing means into an occlusal splint in order to sense the onset of bruxing. These approaches require the presence of electrical devices in the mouth, including, in many cases, batteries, which may contain highly toxic substances. The electrical and chemical health risks of these devices add to the general drawbacks of intra-oral splints described above. In addition, many of these attempts have resulted in bulky devices which would be even more uncomfortable for the user than traditional occlusal splints.
It is the object of this invention to provide a convenient, comfortable, reliable, effective, economical, aesthetically pleasing means of providing long-term biofeedback to treat bruxism. It is a further objective of this invention to provide a bruxism treatment means which does not interfere with normal daily activities. It is a further object of this invention to avoid the presence of occlusal splints or other foreign objects in the mouth of the user. It is a further object of the invention to avoid the adhesive attachment of electrodes to the skin of the user. It is a further object of this invention to provide a user-friendly means for clinicians and bruxers to gather comprehensive data on the occurrence of bruxing events including time, duration, and intensity data. It is a further objective of this invention to provide a means for treatment of bruxism (or gathering of data on bruxism) which is wearable as an attractive, unobtrusive, comfortable article of clothing, which does not interfere with normal activities. It is a further object of this invention to provide a reliable, robust bio-feedback mechanism which is readily perceived by the user while remaining relatively unnoticable to persons in the user's immediate surroundings.
SUMMARY OF THE INVENTION
The general approach of the invention is to sense bruxing by sensing the electrical activity of “obruxism muscles” (the temporalis and/or masseter muscles used to close the jaw). The electrical signal from the bruxism muscles is processed by an electronics module. When a threshold of intensity and duration is exceeded, a signal is generated to provide feedback to the user, indicating the onset of a bruxing event. Data (including time, duration, and intensity) may also be stored internally in response to a bruxing event. These data may be read out through connection to a personal computer, or via voice synthesis or a display.
In one embodiment of the invention, three sensing electrodes are mounted to the inside of a headband which is worn around the user's head above the ears. One of these electrodes (the sense reference electrode) contacts the user near the center of the forehead and provides a reference bias voltage to assure that the input voltage at the sense electrodes is within the linear measurement range of the input amplifiers. The presence of a third electrode also allows for maximum input impedance on the other two electrodes (the sense electrodes). The sense electrodes are mounted such that they contact the user's head near the temples. The voltage between the temple electrodes is amplified and filtered to yield a signal indicative of the tension in the fibers of the temporalis muscle. In another embodiment sensing primarily the temporalis muscle (shown in FIGS. 2 and 3 ), the electrodes are implemented as the ear wires of a pair of eyeglasses (FIG. 4 H). An alternate implementation for sensing primarily the temporalis muscle is an around-the-ear clip or conductive rubber band as shown in FIGS. 4F and 4G.
The electrodes are held in contact with the skin by spring or elastic force, requiring no adhesives. The electrodes are preferably made from materials which are impermeable to water. Moisture naturally present in the user's skin builds up between the electrode and the user's skin in a short time, allowing the skin to become conductive enough for the device to work without the need for special chemicals to be applied to the electrodes. The “moisture build-up” time is usually between 20 seconds and 2 minutes, and can be reduced essentially to zero if the user's skin is wiped with something damp just before putting on the apparatus.
Two embodiments sensing primarily the masseter muscle signal are shown in FIGS. 4A-4H.
In one embodiment the electronics module amplifies the voltage between the temporal electrodes in the frequency range 200 to 600 Hz (the frequency range in which the temporalis muscle is most active), while attenuating 60 Hz to enhance immunity to interference from magnetic and electric fields generated by common household wiring and appliances. A preferred embodiment uses a 60 Hz notch filter with a Q greater than 10. When the sensed voltage exceeds certain time and amplitude criteria, the electronics module generates an alert signal. The alert signal is an audible tone in a piezoelectric transducer worn by the user, and the volume of the tone increases until the sensed bruxing ceases, or until a maximum volume is reached. If the piezoelectric transducer is worn in contact with the user's head, such as at PET1. shown in FIG. 10 (and FIGS. 8A, 8 C, 11. and 12 ), sound may efficiently be coupled to the user's skull so that it may be heard well in both ears at a level substantially louder than would be heard through the air by anyone near the user. This reduces the likelihood of disturbing a sleeping partner. Sound coupled through the air to others nearby may be further reduced by surrounding the side of the piezo electric transducer not in contact with the user with sound-absorbing material.
In order to reduce the potential interference with the sense electronics from signals coupled into the user by the piezo electric transducer, the electrode of the piezo electric transducer closest to the user's skin may be at ground potential (the reference potential for the input electrodes). If this electrode is allowed to contact the user's skin, it may actually serve as the reference sense electrode.
In addition to the audio tone, electrical signals indicative of threshold triggers and the instantaneous level of muscle electrical activity may be available as outputs for data recording for diagnostic purposes. These outputs may be connected to data recording apparatus either directly via wires, or via wireless transmission, such as infrared, radio frequency, or ultrasonic.
In a preferred head-band-style embodiment of the invention shown in FIGS. 8A, 8 B, and 8 C, the circuitry is assembled on a flex-circuit substrate 100 shown in phantom in FIG. 11. Regions of the substrate are stiffened to allow mounting of some components. A liquid crystal display (LCD) 102 and two user-actuatable buttons 104 and 106 on the front of the headband 50 allow the setting of various parameters such as sensitivity and alarm loudness, and the readout of event count and accumulated event duration information. Rechargeable batteries 108 (FIG. 12) allow the unit to operate for over a week under normal usage patterns (8 hours per day). Batteries 108 are recharged by attaching two clips to two externally exposed rivets 110 (FIGS. 8 C and 12 ). The circuitry is sewn inside a flexible rubberized fabric 112 (FIG. 8 B), which increases comfort, gives aesthetic appeal, and affords protection of sensitive circuit components from external static discharge. Fabric-reinforced conductive rubber electrodes are riveted 114 to the flex-circuit through the rubber/fabric enclosure, which is folded over 116. and sewn to itself). This allows a gas-tight electrical connection from the flex-circuit to the electrode (offering long-term reliability and resistance to corrosion). This electrode attachment also aesthetically covers the connection rivets 114. and keeps them out of contact with skin chemistry, reducing corrosion and discomfort. Piezoelectric transducer PET1 provides an acoustical bio-feedback signal to the user, indicative of bruxing activity. One electrode of Piezoelectric Transducer PET1 contacts the user's skin and serves as the reference input electrode.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows schematically, a muscle diagram, showing the location of the temporalis and masseter muscles (the muscles used for chewing).
FIG. 2 is a schematic view of a headband of the invention on a user's head, showing how electrodes of an embodiment of the invention are located relative to the temporalis muscles.
FIG. 3 is a partially exploded view of a headband mbodiment of the invention, showing the electrodes and an electronics module.
FIG. 4A shows an embodiment where the electrodes are implemented as conductive ear-contacting pads on a headphone-type “C” shaped head band.
FIG. 4B shows an embodiment where the electrodes are implemented as a pair of conductive, in-the-ear plugs.
FIGS. 4C and 4D show an embodiment where the electrodes are implemented as a pair of clip-on or through-the-ear earrings respectively.
FIG. 4E shows an embodiment where the electrodes are held in contact with the user's skin just below the jaw via an elastic: neck band.
FIGS. 4F and G show alternate preferred embodiments of the invention for around the ear electrode schemes for sensing the masseter muscle.
FIG. 4H shows an embodiment of the invention including electrodes as glasses frames, for sensing the signal on the temporalis muscles.
FIG. 5A is a schematic block diagram depicting an embodiment where operating-condition-sensing circuitry SOC senses a condition at electrodes E2 and E3 (through differential amplifier DA) which indicates whether the unit is connected to the user.
FIG. 5B is a schematic block diagram depicting an embodiment where the power to both Differential Amplifier DA and signal Processing circuitry SP2 are controlled by electronic Switch ECS1. where electronic switch ECS1 may be turned on and off by Push-button Switch PB, or may be turned on by PB, and turned off a fixed amount of time later by Timer T1 .
FIG. 5C is a schematic block diagram depicting an embodiment detailing a possible embodiment of Signal Processing block SP, including an analog-to-digital converter and a microprocessor UP and a memory M. and
FIG. 5D is a schematic block diagram depicting an embodiment where time keeping and alarm means ALM have been added to provide an alarm-clock-type function.
FIGS. 6A-6C shows circuit block diagrams of alternative embodiments of the invention.
FIG. 6D shows various signals pertinent to the invention, with respect to time.
FIG. 7 Part 1 shows an instrumentation amplifier portion of a circuit schematic of a preferred embodiment of the invention.
FIG. 7 Part 2 shows a filter portion of a circuit schematic of the embodiment of the invention shown in FIG. 7 Part 1 .
FIG. 7 Part 3 shows the power in and output portion and other portions of a circuit schematic of the embodiment of the invention shown in FIG. 7 Part 1 and FIG. 7 Part 2 .
FIG. 7 Part 4 shows additional portions of a circuit schematic of the embodiment of the invention shown in FIG. 7 Part 1. FIG. 7 Part 2 and FIG. 7 Part 3 .
FIG. 8A is a schematic view, predominantly from the side that faces away from a user, showing electrodes and an electronics module.
FIG. 8B is a schematic view from the side that faces the user showing how folded over fabric/rubber electrodes are electrically connected and mechanically sewn in place.
FIG. 8C is also a schematic view, predominantly from the side of a preferred embodiment that contacts the user, also showing the electrodes and an electronics module and showing how the stainless steel back of a piezoelectric transducer acts as ground reference electrode.
“FIGS. 9 A and 9 B: Detailed circuit diagram of a preferred embodiment of the invention, where a microprocessor, digital display, and two switches allow setting of sensitivity, alarm volume, and on/off functions, and where cumulative data on number of bruxing or clenching events and total duration of bruxing and clenching can be displayed. In this embodiment, the microprocessor automatically shuts off power to the analog circuitry and goes into a super-low power sleep state after seeing an above-trigger-level signal for more than 30 seconds,” and insert therefor:
FIG. 9A Part 1 shows a microprocessor portion of a detailed circuit diagram of a preferred embodiment of the invention.
FIG. 9A Part 2 shows a digital display portion of a detailed circuit diagram of the embodiment of the invention shown in FIG. 9A Part 1 .
FIG. 9A Part 3 shows a battery and charging circuit portion of a detailed circuit diagram of the embodiment of the invention shown in FIG. 9A Part 1 and FIG. 9A Part 2 .
FIG. 9B Part 1 shows an instrumentation amplifier portion of a detailed circuit diagram of a preferred embodiment of the invention.
FIG. 9B Part 2 shows a filter portion of a detailed circuit diagram of the embodiment of the invention shown in FIG. 9B Part 1 .
FIG. 9B Part 3 shows an event discriminator portion of a detailed circuit diagram of the embodiment of the invention shown in FIG. 9B Part 1 and FIG. 9B Part 2 .
FIG. 9B Part 4 shows a tone generator portion of a detailed circuit diagram of the embodiment of the invention shown if FIG. 9B Part 1. FIG. 9B Part 2 and FIG. 9B Part 3 .
FIG. 10 is a schematic view (with some hidden parts shown) of a preferred headband-type embodiment of the invention, on the head of a user.
FIG. 11 is a schematic view (with some hidden parts shown) of a preferred headband-type embodiment of the invention, unclasped.
FIG. 12 is an exploded schematic view of a preferred headband-type embodiment of the invention.
A generalized block diagram of the invention is shown in FIG. 6A. A set of electrodes E held mechanically in contact with the user's skin picks up signals generated by bruxism muscles (along with electrical noise and interference). Differential signals from at least one pair of electrodes are selectively amplified by Amplifier/Filter AF. The output of amplifier/filter AF is a signal S1. indicative of the activity level of bruxism muscles. Signal S1 is processed by signal processing means SP to determine when the bruxing activity present is worthy of some action (such as recording as data, or providing biofeedback). The intent of providing biofeedback is to provide the user with a perceivable signal, which, when present, will cause the instinctive or automatic interruption of the bruxing activity. Biofeedback means BF may be implemented as audio feedback means SK (such as a piezoelectric transducer or earphone), vibratory feedback means M, electrical shock feedback means SH, or light feedback means LT.
FIG. 2 is a perspective view of a two-electrode implementation. Conductive rubber sense electrodes E1 and E3 are sewn inside headband HB1. Electrodes E1 and E3 contact the user's head near the temples, and pick up signals from the temporalis muscles TM. Electrodes E1 and E3 are connected via snaps SN to electronics module M1. In-the-ear audio bio-feedback transducer SK is hard-wired to electronics module M1. Slide witch PSW turns on and off power to electronics module M1 .
FIG. 3 is a perspective view of an embodiment where the electronics are contained within snap-on module M1. Snap-on odule M1 connects to sense electrodes E1 and E3 (which contact the sides of the head near the temples) via snaps SN. Ground reference electrode E2 contacts the forehead. Headband HB1 is free to slide back and forth through loop-shaped electrodes E1. E2. and E3. allowing the headband to shift some without moving the electrodes. Headband HB1 is fastened via hook and loop type fastener patches VP. Operational characteristics (such as audio bio-feedback volume, trigger sensitivity, and reading out and clearing stored data) are controlled by push-button switches PBA and PBB. Stored data such as number of events and total seconds of bruxing activity may be read out on display D. In some embodiments, bio-feedback volume and trigger sensitivity may be controlled by rotary analog controls RC1 and RC2. Audio biofeedback may be provided through a piezoelectric element of an earphone connected to socket BFS1. Recharging of internal rechargeable batteries may also be accomplished through socket BFS1 .
In the embodiment shown in FIGS. 8A, 8 C, 10. 11 and 12. a piezo electric transducer PET 1 is used to provide audio feedback to the user. The piezo electric transducer PET 1 is mounted in the headband as shown, such that its metal (e.g. stainless steel) cover 118 (FIG. 12) is in direct contact with the skin of the user's forehead, as shown in FIG. 10. This cover, 118. may also serve as the reference (ground) input electrode E2 for the input circuit. This arrangement provides a significant degree of acoustic coupling to the bones of the user's head, and thus to the user's auditory system, without providing any significant coupling to the air around the user. Further, acoustic transmission to the air can be further damped by surrounding the surfaces of the piezo electric transducer that face the air with an acoustic damper. A suitable piezo electric transducer is one of the type that is commonly used in a low cost digital alarm watch.
As shown in FIGS. 8A, 11. and 12. rivets 120 can connect the piezo electric cover to the flexible circuit substrate 100. so that it can serve as the electrode.
Each of the two electrodes 122 and 124. serving the functions of E1 and E3. respectively, discussed above, can be conductive rubber patches that are sewn to the inside (user-facing surface) of the headband. The patches are themselves electrically connected to the flexible circuit board, such as with rivets 114. shown in FIG. 8 B. In this manner, the rubber electrodes are conductively connected to both the user's forehead and the circuitry. In the embodiment shown in FIGS. 8A, 8 C, 11 and 12. the cover 118 serves as the third electrode, E2. It is also possible, instead, to use a conductive rubber patch similar to that shown at 122 .
Normally, the function of the electrode set E and the amplifier/filter AF can be thought of as linear. Any increase in bruxing activity will cause a proportional increase in bruxism signal S1. It is often desirable that the processing after S1 be non-linear. For instance, it may be desirable that only events stronger than a certain threshold are ever logged as data or seen as sufficient to warrant biofeedback. The defining of this threshold is a non-linear operation. Anything less than the threshold results in no output, and anything above the threshold results in an output. The key variables of interest in processing bruxism signals are amplitude (or intensity) and time (duration, repetition rate, etc.). It may, for instance, be desirable to detect repetitive brief clenching of the jaw, as well as sustained clenching, while it may also be desirable not to detect a single, isolated, brief muscle contraction, such as might happen when the user shifts position in bed.
It is desirable for the input stage of amplifier/filter AF to be robust in several key ways. First, in connecting conductively to the skin of a person, the chemistry of the connection interface may vary widely. These chemical variations may come from sweat, lotions, perfume, etc. Differing surface chemistry at two different electrodes can result in a significant offset voltage. This voltage is like a small unknown battery creating a voltage in at the electrodes, and may be thousands of times the amplitude of the relevant signal. This offset voltage varies very slowly compared to the frequencies of interest in the bruxism signal, so it can be conveniently filtered out by high-pass filtering (also known as “AC coupling”). It is desirable that the break frequency of the high-pass filter is at or below 200 Hz, in order not to attenuate any of the relevant bruxism signal.
It is desirable that the input impedance of amplifier/filter AF be high, and that the needed bias current for the input stage be as low as is practical. A high input impedance and low bias current results in the lowest possible current flowing through the person's skin. This is desirable both from a regulatory standpoint (UL regulations in the USA, and other analogous regulations abroad), and from an electrochemical standpoint. Any current that flows completes a chemical reaction at the surface of the skin, and will, to some extent, combine the electrode material with that of the user's skin. This can cause staining of the skin, irritation, etc.
It is also desirable that the input stage be designed to withstand common static discharges, as those a person might experience after walking across a carpet and touching something conductive, or as might occur when playing with a pet cat. It is also desirable that the amplifier/filter have a negligible response to common forms of electromagnetic interference. The most relevant being 60 Hz interference as might be picked up from common household utility wiring and appliances.
In order to sense the signal from the bruxigm muscles, at least two electrodes (E1 and E3 ) are required. If a third electrode is added, the input impedance of the amplifier/filter AP may be maximized. In order for any amplifier to operate, some (normally minute) bias current must be provided for its inputs. This bias current is needed to maintain the amplifiers inputs within their operational voltage range. The addition of a third electrode E2 allows this current to be supplied without compromising the input impedance of the amplifier. In FIGS. 6A and 6B, this third electrode E2 is shown connected to electrical ground. It is assumed here that electrical ground as it is defined in the circuitry is within the operating voltage range of the input amplifier. As an alternative to providing a third electrode as shown in FIG. 6C, resistors RE1 and RE3 may be provided to allow the biasing of the amplifier. The addition of RE3 and RE4 will, however, always result in a lower input impedance (and therefore a chemically more interactive set of electrodes). Another disadvantage of a lower input impedance is that a lower electrode contact resistance will be required for reliable detection of the signal from bruxing muscles. Thus a lower input impedance makes the design of reliable electrodes harder. For a system using no electrode chemistry to reduce skin resistance, it is doubly important to provide a high input impedance.
A more detailed block diagram of one embodiment of the invention is shown in FIG. 6 B. Here amplifier/filter AF has been expanded into separate amplifier (DA) and filter (BPF) functions. Three electrodes E1. E2. and E3 are held in contact with the user's skin without the aid of adhesives. The signal sensing electrodes E1 and E3 are disposed on opposite sides of the user's head, and provide signal input for differential instrumentation amplifier DA. It is also possible to place one of the sense electrodes on the user's forehead, and for the ground electrode to be toward one side of the head, but this configuration provides less immunity to triggering by eyebrow movement and other use of facial muscles. Electrodes E1 and E3 pick up the desired muscle potential signal (along with undesired environmental electrical noise and interference) conductively through the skin. The reference electrode E2 contacts the user preferably somewhere near the median plane bisecting the head, and provides a ground reference and needed minute bias current for amplifier DA. The muscle signals of interest are typically in the range of 0.01 to 0.1 mV in amplitude. These signals are generated by electrochemical depolarization and repolarization within muscles and nerves as the individual muscle cells “fire” and contract. Throughout a muscle, individual muscle cells fire at different times in different places. This can be thought of as a process like popcorn popping. The overall strength of contraction of the muscle at a given moment comes from how much corn per second is popping at the time. If one looks at the overall electrical signal from a muscle, it can be thought of as the noise the popcorn makes. Unlike popcorn, however, the muscle cells don't fire only once, they fire and then relax and then can fire again. The repetition and statistical popping phenomena result in most of the electrical energy of the muscle signal being concentrated in the range of 200 to 600 Hz in frequency. Components of the muscle signal exist outside this frequency range, but are not as strong.
The signal from differential instrumentation amplifier DA is applied to band-pass filter BPF. The transfer function of filter BPF gives maximum gain between the 3 dB frequencies of 200 Hz and 600 Hz (the band in which most of the power in the jaw muscle signal lies). The gain of the filter at the 3 dB frequencies is down to 0.707 times its peak gain, and the gain falls off rapidly outside these frequencies. Filter BPF also provides a deep, narrow rejection notch at 60 Hz, to facilitate immunity to electromagnetic interference from household appliances and electrical utility wiring. The notch feature of the filter gives much better performance than a band-pass filter without a notch. A preferred embodiment uses a notch filter with a Q greater than 10. An ordinary forth order band-pass filter with a lower 3 dB frequency of 200 Hz would provide attenuation of 3.3 (about 10 dB) at 60 Hz. Including the notch function, an attenuation of more than a factor of 30 (about 30 dB) can be achieved.
The signal from the output of filter BPF is applied to the input of muscle threshold detector MD. This is the first non-linear element in the signal processing chain. In FIG. 6B, the signal processing block SP of FIG. 6A has been expanded into seven functional blocks. The combined function of these blocks is to provide bio-feedback (and data output), whenever there has been at least a certain amount of bruxing muscle activity above a certain threshold within a certain period of time.
Examples of signals that will “set off” the signal processing arrangement of FIG. 6B are shown in FIG. 6 D.
FIG. 6D shows exemplary waveforms showing the timing and amplitude relationship between signals S1. S2. S3. S4. and S5. as identified in the block diagram in FIG. 6 B. Detector MD serves to detect when muscle signals of sufficient intensity to warrant further analysis are present. The output of muscle threshold detector MD, denoted S2. may be considered to be a digital signal, with two possible instantaneous values (0 and 1). S2 is zero all the time if the muscle signal being measured is very small, and is 1 a higher percentage of the time as the muscle signal gets stronger. The percentage of time that S2 is 1 approaches 50% as the muscle signal gets very strong. Signal S2 can be thought of as an AC signal with a variable DC bias riding on it. For strong muscle signals, the DC bias approaches half the peak value of S2. The AC portion of S2 always has its fundamental energy between 200 Hz and 600 Hz. For low muscle signals, S2 is “peaky” and has a lot of energy at higher harmonics. For higher muscle signals, where S2 is one almost half the time, S2 has most of its fundamental energy within the 200 to 600 Hz frequency band, and has the relative harmonic content of a square wave. Because the input signal to muscle threshold detector MD is a band-passed signal with most of it's power between 200 Hz and 600 Hz, the average pulse length at the output of detector MD will be about 1.2 milliseconds. The threshold of muscle threshold detector MD is adjustable to allow the user to determine what level of bruxing should be detected.
Low-pass filter LPF averages the output of muscle threshold detector MD over a period of time which is long compared to the average 1.2 millisecond pulse length of the output of muscle threshold detector MD, but short compared to human reaction time (about 0.1 sec). The output of filter LPF may be thought of as an analog voltage which is representative of the intensity envelope of the muscle signal being measured between electrodes E1 and E3. When this envelope exceeds a predetermined value, event detector ED indicates (via signal S3 ) that there has been enough bruxing activity “recently” to count as a bruxing event (a situation where there has been enough muscle activity at a sufficient intensity to indicate at least a brief clenching of teeth).
Event detector ED is a threshold detector which serves to detect when the muscle activity envelope has exceeded the allowable limit. When this limit is exceeded, audio oscillator AO is turned on, and the user will be able to hear a faint tone from audio transducer SK (which may be, for instance, an earphone or a piezo electric transducer held in a headband to the user's forehead). The output of limiting integrator LI begins to ramp up as soon as the output of event detector ED becomes active. As S4 (the output of integrator LI) ramps up, the gain of variable gain amplifier VGA increases proportionally, and the tone heard in audio transducer SK increases in volume. When the limit of limiting integrator LI is reached, the output volume of audio transducer SK remains at a maximum. The ramping rate of integrator LI is adjustable. Adjusting to a slower ramp rate allows the user to stop bruxing without being awakened if the device is being used at night (the user will respond by ceasing bruxing activity before the tone gets loud enough to awaken the user). As can be seen in signal S4 in FIG. 6D, the output of the limiting integrator in this embodiment is initially negative. The time taken for the S4 to ramp from its initial negative value to zero serves as a “minimum bruxing duration” delay. This delay may be used to prevent triggering on short isolated bruxing events, if desired. Repetitive bruxing bursts will allow the integrator to ramp up beyond zero, if they are closely spaced in time. Thus, repetitive clicking of teeth (a common form of nocturnal bruxism) will result in biofeedback. The aim here is to provide biofeedback for the majority of events that can lead to cumulative damage to teeth, while not responding to events that could come from something like a person moving to a new sleep position.
Enabling audio oscillator AO from S3 (the output of event detector ED) provides the additional feature that if the person stops bruxing in response to the tone heard through the audio transducer, the tone stops immediately, rather than ramping back down slowly with the output of limiting integrator LI.
Power is supplied to the unit by battery stack B (4 lithium coin cells), through power switch SW.
Other embodiments of the invention than the one shown schematically in FIG. 6B are contemplated. The signal processing block SP may include numerous timing and auxiliary functions, as illustrated in FIGS. 5A-5D. For instance, as shown in FIG. 5B the power switch SW may be modified to be an electronically controlled switch ECS1. allowing part of the circuitry (for instance, the bio-feedback and data logging) to be switched while the front end amplifier is designed for extreme low power consumption and may remain continuously active. This feature combined with the addition of circuitry SOC for sensing proper operating conditions, allows for an automatic on/off function. (The remainder of signal processing block SP in this implementation is shown as block SP2 .) One possible implementation of such a function assumes that amplifier/filter AF is designed such that if the unit is removed or improperly worn, the output from amplifier/filter AF goes out of range. When proper operating conditions are present (electrodes making good contact with skin, no bruxing event currently being detected), the output of amplifier/filter AF is in range. The front end of signal processing block SP (detector SOC) may be implemented with the ability to detect this condition and shut down the unit. The unit may be shut down immediately or after several seconds of alarm, alerting the user to correct the problem if it is not intentional. The electronics may be designed to overload on 60 Hz and provide a continuous brux indication when removed from the head, so that the prolonged brux signal may be used to implement an automatic shut-off feature. In another embodiment, shown schematically in FIG. 5B, electronically-controlled switch ECS1 may be activated in aresponse to a momentary push-button switch PB, and deactivated in response to timer T1. allowing the user to turn the unit on for a predetermined period of time (for instance by a momentary push-button). This feature may be combined with the automatic-off function described above, for convenience and minimal power consumption. In such an embodiment, the user turns the unit on with a push-button, and the unit turns itself off a set time after having been removed. This embodiment and others may incorporate means allowing for the automatic disabling of the bio-feedback means for a fixed time after the unit is turned on (to allow the electrodes to “sweat in” and become reliable contacts).
In another embodiment, shown schematically in FIG. 5C, signal-processing means SP may include an analog/digital interface AD, a microprocessor UP and memory M, allowing the digital storage and retrieval of bruxing event data, including event timing, duration, and intensity data. Retrieval may be accomplished by connecting a personal computer or the like to an RS232 interface SI (implemented on many single-chip microprocessors). For ease of interfacing to the user, data retrieval may also be accomplished by a microprocessor-driven Voice interface VI, using a voice synthesis chip such as are used to time-stamp messages on telephone answering machines. Voice interface VI and bio-feedback means BF may interface to the user through the same audio transducer SK. In addition, the character of the bio-feedback signal provided may be varied over time, to prevent the user getting “used to it” and “tuning it out”. For instance, in an embodiment using audio bio-feedback, the sound could be a tone one time, a barking dog the next, and a meowing cat the next.
Further features may be added, giving additional functionality and value to the consumer. In one embodiment, shown schematically in FIG. 5D, an “alarm clock” function may be added, utilizing time keeping and alarm means AF, that can either wake up the user at a specific time of day (via the bio-feedback means), or after a pre-determined time (to allow, for instance, for 8 hours of sleep). Time keeping and alarm means AF may be set via push-buttons PB2 and PB3. and may sound the alarm through audio bio-feedback means SK.
FIG. 7 is a schematic circuit diagram of a preferred embodiment of the invention shown in block diagram form in FIGS. 6A-6C. Other circuit implementations would be evident to one of ordinary skill in the art, and the embodiment shown in FIG. 7 is not intended to be limiting in any way. Wires from the electrodes come in through a housing H via connector J1. Resistors R38 and R39 provide current limiting to prevent damage from static discharge. Amplifiers U1 A and U1 D, together with R35. R36. R37. and C13 comprise a high-input-impedance differential input amplifier DA. Capacitor C36. in conjunction with resistor R36 lowers the DC gain of the differential input amplifier to unity, while the in-band gain is 10. This allows immunity to chemical offset voltages at the electrodes.
Amplifier UlC, in conjunction with resistors R1. R32. R2. and R31. and capacitors C12 and C14 comprise a differential-to-single-ended converter, which together with the input differential amplifier constitutes differential instrumentation amplifier DA.
Amplifiers U2 A, U2 B, U2 C, and U2 D, in conjunction with resistors R21. R22. R23. R24. R26. R27. R28. R29. R30. R33. R34. R3. and capacitors C1. C2. C8. and C9 comprise band pass filter B/F, with a pass band between 200 and 600 Hz, and a rejection notch at 60 Hz. Potentiometer R3 may be used to precisely tune the 60 Hz rejection notch.
Capacitors C17. C16. C7. and C11 provide bypassing of the power supply rails, which are derived from battery stack B through connector J3 .
Amplifier U2 B, in conjunction with potentiometer R4 and resistor R16 comprise variable threshold detector MD.
Resistor R25 and capacitor C10 constitute low-pass filter LPF.
Amplifier U3 A, in conjunction with resistors R5. R18. and R19 constitute threshold detector ED.
Transistor Q2. in conjunction with resistors R9. R20. and diode D1 A, provide buffered data output DO1. The signal buffering provided by Q2 prevents attached data-logging equipment from affecting the operation of limiting integrator LI.
Amplifier U3 C, in conjunction with resistors R6. R10. R12. R13. capacitor C6. and diode DIB constitute gated audio oscillator AO.
Amplifier U3 D, in conjunction with Capacitor C3 and resistor R17 constitute limiting integrator LI.
Transistor Q1. in conjunction with resistors R7. R8. and R14. capacitors C4 and C5. and amplifier U3 B constitute variabl-egain amplifier VGA.
Transistor Q3. in conjunction with resistors R11 and R15. and diode D2 B, provide buffered data output DO2. Capacitor C1 S rovides coupling for audio output AO1. Data outputs DO1 and DO2. and Audio output AO1 are available through connector J4. Piezo audio is available through connector J2 .
FIGS. 9A, Part 1. 9 A Part 2 and 9 A Part 3 and 9 B, Part 1. 9 B Part 2. 9 B Part 3 and 9 B Part 4 show detailed circuit diagrams of a preferred embodiment of the invention. A microprocessor, digital display, and two switches allow setting of sensitivity, alarm volume, and on/off functions. Cumulative data on the number of bruxing or clenching events and the total duration of bruxing and clenching can be displayed. In this embodiment, the microprocessor automatically shuts off power to the analog circuitry and goes into a super-low power sleep state after seeing an above-trigger-level signal for more than 30 seconds.
SOME IMPORTANT FEATURES
Some important features of the invention include:
Non-adhesive pressure-contacting electrodes;
Wearable bruxing detector;
Data-logging (event count, duration info, time of incident info);
Can be neck band;
Some embodiments use temporalis-only detection;
Can be head band;
Can be “C” band (like headphones);
Pickup electrodes can be Ear clips;
Pickup electrodes can be ear inserts;
Pickup electrodes can be earrings;
Pickup electrodes can be glasses frame;
Integration following threshold detector to generate alarm (not novel except in combination with other features);
Hydraulically impermeable electrode surfaces;
Alarm intensity ramp;
Delayed start after power-up (Settle-in timer);
Front end powered all the time that powers up rest of unit if in linear range for a given time;
Auto-shut-off after predetermined time;
Combination with transmitted data logging (ultrasonic or IR or Radio);
Back of audio actuator (for example, the cover of a piezo electric transducer) may be a conductive surface which doubles as ground reference electrode;
Coupling audio signal mechanically to the bones of the user's head is highly efficient and gets sound to both ears, while still being much quieter to person sleeping next to user;
Early removal alarm;
Separable cloth and electrodes;
Headband can use rubber loop electrodes;
Internal RAM and UART;
Data logging of intensity logging of number of events logging of timing of events.
Flex-circuit sewn inside fabric headband for comfort and aesthetics;
Conductive rubber electrodes sewn on or conductive rubber applied directly to areas of fabric;
Thin conductive-rubber-coated-fabric patches may be sewn on as electrodes, and folded under at the edges for attachment to flex-circuit by rivets (which get automatically covered by the folded over fabric).
The foregoing discussion should be understood as illustrative and should not be considered to be limiting in any sense. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the claims.