A continuous, almost maddening ringing in your ears, anyone who suffers from tinnitus experiences it every day and there is no solution. Scientists have now discovered where this ghost sound comes from: it is hyperactive nerves that the nervous system can no longer switch off.
One in ten people has tinnitus, also known colloquially as tinnitus. It is often caused by prolonged exposure to loud noise, for example during concerts or in discos. It manifests itself as a long buzzing, noise or, for example, a beep in your ears. Some people suffer from it occasionally, but for others it is chronic. It is often so intense that it leads to psychological problems, such as depression.
“Besides the fact that it is annoying to have a continuous ringing in your ears, tinnitus is very limiting in many patients. It causes sleep problems, social isolation, anxiety disorders and depression. It also has a negative impact on work performance and reduces the quality of life,” explains scientist Stéphane Maison from Massachusetts Eye and Ear.
Medical mystery
It was for a long time a medical mystery how it could arise, but American researchers have now evidence foundwhich supports the main theory about the origin of the annoying buzz.
Because there is no physical vibration causing the sound, the main hypothesis is that tinnitus originates in the nerves that normally transmit sound information to the brain. It would be the brain’s way of compensating for hearing loss. Turning up the volume when there is little or no sound coming in also makes the background noise from our internal speaker louder, leading to that annoying buzz.
Damaged nerves
To demonstrate this, almost three hundred people between the ages of 18 and 72 were examined. They had normal hearing according to the usual tests. 29 of them had continuous tinnitus for more than half a year and another 64 had it for less than six months or sometimes yes, sometimes not. About a third had never had the condition.
There appeared to be a link between self-reported chronic tinnitus and damage to the auditory nerve. That nerve can be damaged by excessive noise exposure, but also as a result of normal aging, even if the hearing cells remain intact.
Weaker muscle reflex
The extent to which someone suffered from tinnitus turned out to be a strong predictor of damage to the auditory nerve. The tinnitus patients had a weaker muscle reflex in the middle ear, which is supposed to protect our ears from loud, low-frequency noise, such as the bass in a nightclub. They also had a stronger olivocochlear reflex, which normally helps us process sounds, which are spread over much of the audible range.
The worse the tinnitus, the stronger these responses were. According to the researchers, this means that the extent to which tinnitus is permanent may depend on the degree of peripheral nerve damage. “Our work confirms the idea that tinnitus is triggered by auditory nerve loss, even in people with normal hearing,” Maison explains.
Treatment closer
Previous studies in rodents discovered that a group of proteins called neutrophins can be used to stimulate the auditory nerve to repair itself. The researchers hope that their new findings will accelerate research into the use of this treatment in humans.
“We cannot cure tinnitus until we fully understand the mechanisms behind its development. This study is a first step towards our ultimate goal of silencing tinnitus,” said Maison. “The idea that researchers might one day be able to return the missing sound to the brain and perhaps reduce the hyperactivity of the auditory nerves brings the hope of a cure much closer to reality.”
2023-12-05 18:02:07
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