What is Tinnitus?
Tinnitus arrives in a number of sounds, volumes, and patterns. Tinnitus can be a ringing, roaring, beating, clicking, banging, buzzing, hissing, humming, chirping, clanging, sizzling, whooshing, rumbling, whistling, or dreadful shrieking noise. To many people, Tinnitus appears like running water, breaking glass, or chain saws running. The degree of the noise can fluctuate from fine to shattering. This is the noise that seems to originate in the ear or head.
Patients really suffer from it. And it is very widespread, about 50 million Americans suffer from it. I bet a lot of you in the audience have friends or family who suffer from it. What I’m talking about is Tinnitus, ringing in the ears. He is frequently depicted in this painting by Edvard Munch, although we do not know for sure if he himself had Tinnitus. But the person in the painting covers his ears and this doesn’t help because the buzzing is actually generated in the brain. It is not a real sound that the person hears; it’s a ghost sound. So we often talk about it as a buzzing in the brain more than a ringing in the ears. And of those 50 million Americans who suffer from it, about 10 million of them have it really bad, they reach the point of having depression and suicidal ideas.
I receive emails daily from patients asking, “Isn’t there a cure?” So far, unfortunately, there is no cure. And part of our research focuses on that, of course, we are trying to find ways to help these patients. And I can give you some examples (Sharp tone) of how it sounds. This is a relatively rare, single frequency, pure tone. Usually, Tinnitus sounds more like the following. (Whistling sound) You can imagine how annoying it is if they hear that all the time in one or both ears.
They cannot put it out, they cannot run from it; it is always there. (Cricket sound) Sometimes they get this more sophisticated cricket sound they hear now. So, people suffer for it. There are groups more affected or at higher risk than others. It happens surprisingly often to musicians because they are exposed to sounds louder than they notice.
I remember being once at the Kennedy Center in Washington, DC. where we live; and we went to a concert there, a symphonic concert of the National Symphony. They played Shostakovich’s War Symphony. Very strong, of course. One of the violinists in the first or second row was sitting right in front of the trombones behind her. The trombone was blowing right in his ear and she covered her ears by reflex to protect herself.
This is, in fact, the right reaction; should avoid loud sounds to avoid damage to hair cells, followed by hearing loss and finally Tinnitus. Exposure to loud noise is one of the biggest risks. Let’s take a group of construction workers. If they don’t have hearing protection, it can be very dangerous. The group most at risk is our war veterans. They are constantly exposed to artillery fire, bombs, explosives, etc., you know. Also, this is a very important factor, that I want to emphasize in this presentation– stress is a very important factor. So it’s not just exposure to loud noises that can cause Tinnitus.
In fact, it doesn’t always, but if combined with a stressful situation, This is the most likely scenario where they will end up with Tinnitus. So our veterans have a much greater chance of returning home from the battlefield with Tinnitus. In fact, the Veterans Administration, if you look at the statistics, show that Tinnitus is the main cause of benefits paid to veterans. Hearing loss is the second most common. Tinnitus has often been compared to other phantom sensations Like phantom limb pain, which you may have heard of.
In this case, someone loses a limb due to an accident or explosion. that hurts your arm or leg. And it is a very similar situation. In this case, once again, the brain is the cause of it. Even though the leg is missing, the neurons in the brain that represent the brain are still there and they continue shooting.
Sometimes the person may have the impression that his leg is still there. And you can really feel pain in that leg. Animal experiments have shown – this is shown on the right of this slide that this is really what is happening. In monkeys that have lost a hand, for example, the representation of the hand is filled with the input of the representation of the face, which is right next to him. Ramachandra and other neuroscientists in California conducted studies on amputees, where they showed that if their faces are touched, they feel their phantom hand more often than if this is not done.
There is a profound reorganization taking place in the brain both in the phantom limb and in Tinnitus, which is the equivalent in the auditory domain. People have often referred to this as maladaptive plasticity. Plasticity, by definition, should be a good thing, right? We learn that this is plasticity; memory is a form of plasticity, so we associate this with an adaptive function. But in this case, is it really adaptive?
I would think so. It is not necessarily maladaptive because the brain has a plan for how to deal with these kinds of situations. So, if exposed to loud noises, are killing some of your hair cells in the inner ear and these cannot be substituted; they do not grow back. So what the brain does is fill that space.
Nature does not like spaces. So space is occupied by neurons that normally respond to other frequencies, as to the right or the left of that space. Another example is the blind spot of the eye. You all know we have a blind spot in our retina where there are no photoreceptors, and the blood vessels go in and out of there. The optic nerve enters through there. We don’t see, but we don’t notice that hole because with the same mechanism the brain fills that hole. And the same thing happens in what we call injury-induced plasticity.
The same thing happens in Tinnitus. So it is, per se, an adaptive mechanism. But it has an unintended side effect, This hyperactivity that we’ve been talking about that we can visualize with an RMf, for example. And so, the next step is missing in Tinnitus patients. Usually, the brain is much more intelligent. You notice this internal noise that is generated, so he puts his executive sentence on the line and suppresses that noise.
So most people, even after extensive exposure to loud noise they do not have Tinnitus. You may have hearing loss but it doesn’t end with Tinnitus. They go to a concert with loud noises, for example, a rock concert, and they may have Tinnitus the next day but it goes away in a few days. So many people have temporary Tinnitus. which is repaired by the brain; there are mechanisms for that.
But those unfortunate people in whom the mechanisms do not work, are the ones that become chronic Tinnitus patients. In the following slides, I’ll show you the brain and how it’s organized how you react to these events and situations. This is the brain as a whole,
And they can see the auditory cortex somewhere in the middle; has been exposed. This is just a drawing. You can see the tonotopic map, how the different frequencies are arranged throughout the auditory cortex. And you can see how … Usually this is very regular. All frequencies are equally spaced, but after this yellow region is lost, the green and orange regions shift and they are the ones that are overrepresented and they cause the sound of Tinnitus, the Tinnitus signal.
Here we have a real picture. This is an old research scanner at NIH, in which some of these techniques have been established. Now, this can be done with any MRI scanner that they have probably seen, or been inside of it. And we can visualize the auditory cortex in the controls without Tinnitus. Activation of the auditory cortex can be seen. And in patients who constantly have Tinnitus, this activation is doubled or tripled; it increases very significantly. This is the physical materialization of what people actually perceive. But this is not the whole story. The rest of the talk will try to convince them that Tinnitus is not just a hearing disorder; it is more than that.
It has to do with the higher brain functions in the frontal cortex, in the limbic system. If you think about it, there is good reason to suppose which is more than a hearing disorder, because, as I mentioned, not everyone ends up with Tinnitus, even if they have hearing loss and have suffered repeated exposures to loud noise. Many people have only intermittent Tinnitus.
If they are like me, they often have stressful situations, as a delivery date that they must meet. They work very hard, they sleep less during that period, and then your Tinnitus appears suddenly. Even if they don’t have it normally, they can get Tinnitus in a situation like this. Then they deliver the project they worked on. They finished, they have a good feeling, they sleep well that night.
The next day, the Tinnitus is gone. That shows them that it is not only auditory. There is a regulator in the brain which normally takes care of this. And there is also comorbidity with depression. If they feel bad and have like a … if they are sad or stressed, then your Tinnitus is more likely to come up and get worse. There is clear comorbidity with this type of mechanism which we often refer to as the limbic system. On the left, the blue region is the auditory system. Each sensory system has its representation in the brain. And in the frontal cortex, in the front of the brain, is this green system, which we refer to as the limbic system, that regulates our emotions. And it has quite defined components, which I will show you in a minute: the ventromedial prefrontal cortex and the nucleus accumbens.
They all play a role and interact with sensory systems and they are capable, like a computer operating system, to emphasize or attenuate what they hear or see, and provide them with the real insight, the experience of your daily life. The result of all that is that Tinnitus is a phantom sensation that depends on three things. First, in most cases there is peripheral hearing damage; there’s no denying it.
Some say that Tinnitus exists without hearing loss, but that is very rare. It can happen occasionally with accidents. But normally, there is an injury. And there is the central auditory organization, as I showed you in the fMRI, And then there’s this non-auditory gate system, and the rest of the talk is just about this. About 10 years ago we made a crucial discovery. That, too, was a brain imaging study which we did in collaboration with the German MIT. He just said it in the introduction, in Munich. And we found that in patients with Tinnitus there is very significant shrinkage in a region. We call it a decrease in volume because MRIs determine the volume of a part of the brain, of brain tissue.
And this was in the ventromedial prefrontal cortex, which is normally there for the perception of unpleasant sounds. A previous study showed that if we hear unpleasant sounds, the same region lights up. So it makes sense that this region has been affected, but we didn’t realize at the time how crucial it was. Another finding that has helped us understand what is happening is that this region in the ventral striatum in the basal ganglia, right there in the middle, you can see the red dot there. This is called the nucleus accumbens.
It is a small center that regulates our emotions. It is often called the pleasure center. In fact, it is involved in generating addictions And it has all kinds of roles in terms of emotional regulation. And surprisingly, this region was very hyperactive. Its activity was increased in patients with Tinnitus. A very significant effect, as you can see on the right if you understand statistics. Those two regions together form an internal noise cancellation system.
It is what we think. You will have had noise-canceling headphones on a plane. And what they do is they can’t really make the noise go away; the noise is still there but the system adds another form of sound to a signal. And that’s the negative form of the original sound and that is cinnamon, there is some noise and therefore you do not hear anything u get a much smoother effect. And that system normally, with the red box there, it inhibits the signal from internal noise and you don’t have Tinnitus. But if that system is broken, then they end up with Tinnitus.
So, in this close-up, you can see that the nucleus accumbens is part of that evaluation system and the medial prefrontal cortex is responsible for volume control; the increase decreases when the nucleus accumbens commands it. And then together this either works or it doesn’t. So where do we go from here? We have the clues from this last slide. You can see the boxes on the right. They are dopamine and serotonin. They are two transmitters. They have to be elevated for one to feel good and happy. If they are diminished, one becomes depressed, for example, and has Tinnitus. So this can open an avenue for long-term drug treatment. But there is another way of treatment that we could use in the future.
It’s called Deep Brain Stimulation and has been established for Parkinson’s disease and major depression. I will show a patient using this treatment in a short video. At first, it may be impressive, but it has become a routine practice in many disorders. The patient is lying awake. She is slightly sedated. You can talk to the surgeon and tell him how you feel. (Video) Mayberg: Do you have any mental qualities or is it primarily physical? Patient:
Actually, this time it was something like … there was a lightness in my mood that went with the lightness of what he felt. Storyteller: The transformation was drastic: a sudden remission of despair, in a person who had spent years in an almost vegetative depression. Happiness was a possibility again. Josef Rauschecker: I hope I was able to tell you that we are getting closer to understanding what Tinnitus is, and with these considerations that I just mentioned, We could finally find a cure and I could answer those emails that come to me and say, “Well, help is on the way.
We are not there yet, but help is on the way. Soon I will have something for you.
Discover more on how you can permanently stop noise in your ears by eliminating the root cause of tinnitus.