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Bionic Ear research targets the brain stem

January 18, 2011
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The Bionic Ear Show presenter Tobin May

The lipreading course I attend each week helps its students understand more about hearing in general, as well as teaching vital skills in dealing with its loss. This week, we had a presentation called The Bionic Ear show which gave an excellent insight into the workings of the ear and also the research currently underway to help correct the things that can go wrong. Aside from the engaging physical demonstrations of how the human ear receives and processes sound, the electron microscope footage in an accompanying video showed how incredibly complex the inner ear structure is and also examples of what a healthy, fully functioning hearing system looks like versus one that has been damaged.

The show’s presenter, Tobin May, explained how mammals can’t regenerate the hearing cells that are essential to the efficient operation of the inner ear whereas birds, fish and some reptiles can. It seems that this ability was switched off in mammals at some point in the evolutionary process but apparently, research in recent years on mice has demonstrated that the process can be switched on again. I had heard about this research before but it seems it is proving far harder to repeat the experimental process in humans, mainly because it is not yet clear why this re-generation ability was switched off and what the likely consequences are of switching it back on again. It is clearly one of those scenarios where it is assumed there was a good reason for the switch off in the first place and tampering with it, without full understanding, risks unforeseen complications.

So, for the time being, those of us who have damaged hearing cells can select from a number of mechanical compensation devices depending on the extent of the damage – from tiny ‘in-the-ear’ aids to sophisticated behind the ear ones to the ultimate bionic ear of today, the cochlear implant. As always, with these type of discussions, Tobin was the first to acknowledge that despite massive advances in digital technologies in recent years, there is still a long way to go before we are anyway near to correcting hearing loss in the same way that so many eyesight issues can be corrected back to 100% original function these days. By way of an example, there are about 3,000 hearing cells in the inner ear and the very best cochlear implant technology today can only compensate for the function of about 30 of these. This is improving gradually but the technology is being stretched to its limits right now. Another interesting area of development that is currently in the fledgling state cochlear implants were in 20 years ago is the ability to bypass the ear mechanisms completely and tap into the brain stem directly. There are only around 5 people worldwide who have had this type of operation and clearly, given the risk of paralysing someone when accessing the brain stem, development in this area is proceeding with extreme caution.

A morning spent learning more about the challenges that the complex mechanisms of the ear present, was followed by a lunchtime appointment with the very clever people from the Wessex Clinical Genetics service who are helping me identify, once and for all, why generation after generation of the family have suffered premature hearing loss and what the prognosis is for current and future generations. I am starting to feel much more confidant that by the end of this year I will have a lot more answers than I do now and hopefully, those who may be affected similarly in the future will not have to face the levels of uncertainty I have faced over the years and can deal with the issues hearing loss presents more swiftly and effectively than I have been able to do.

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