What is tinnitus?

03 September 2013



What causes the noise heard in tinnitus?


Chris - Well, the definition of tinnitus, I hope not in response to this programme Les of course, but the definition of tinnitus is when you have a sound experience in your ears or ear in the absence of any external presentation of sound. So in other words, you're hearing something that you know is not there. It's coming from inside your ear. There's a number of reasons why this can happen. The commonest is because of the ageing process and damage to your ears caused by degeneration of what are called hair cells and inside your inner ear are cells called hair cells that have tiny hairs projecting off of the cell. When vibrations from a membrane inside your ear are transmitted into those hairs, they make the hair cells fire off electrical impulses and they send the electrical impulses via a nerve to the brain stem and then onto the main part of your brain that does the hearing. If you are exposed to very loud sounds chronically, in other words, over long periods of time, we don't exactly know why, but it does damage these cells and eventually, they begin to be lost. This means that the sounds that they would've picked up and sent onto the brain no longer get transmitted to the brain. And it's a bit like if you're listening to the radio and you can't quite hear it loudly enough, you turn up the volume. That means that you don't only amplify the noises you do want. You also end up amplifying the hiss that you don't want. And so, we kind of regard tinnitus as a sort of hissing noise which is brought about by the brain increasing the amplitude or gain in the system, in order to try to make sense of the sounds that seem to now be missing. There are other things that can also cause tinnitus as well and one of them is probably infection. We know that some viruses can make a beeline into your inner ear and can irritate the nerves. In fact, there's been some viruses going around in the last few weeks called enteroviruses that can get into the nervous system. They tend to cause things like headaches and pain behind your eyes. Occasionally, you know you've got one because you can get ulcers in your mouth as well. They can sometimes also cause this tinnitus sensation. Also, don't forget drugs as well because there are certain drugs and medicines that can cause irritation of the cochlea - this is the hearing organ - and they include aspirin. If you take lots of aspirin, you can get ringing in your ears or a drug like aspirin called salicylic acid and also, some antibiotics can also do this as well. Ginny - Are those kinds of tinnitus reversible? So, if you take lots of aspirin, do you get it for a while and then it goes away again or are you stuck with it for life?

Chris - It depends. If you take a lot of aspirin or salicylic acid which is a chemical relative of aspirin, the stuff that's in willow bark, that tends to go away when the drug flushes out of your system. If you take certain antibiotics and this includes the antibiotic gentamycin which is sometimes given for certain deep rooted infections in the body, that is very toxic to the cochlea hair cells and if it damages them, it can sometimes cause tinnitus and ringing in the ear that unfortunately ends up being permanent.


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