Now Hear This!

Ask the DOC

Hearing loss is one of the most prevalent and undertreated disabilities worldwide. In the past it was simply considered one of the stigmata of aging, however, more recently, it has been increasingly recognized as an important health issue that may lead to increased risks of social isolation (not COVID-19 related), depression, loss of autonomy, reduced employability, and neurocognitive dysfunction, not to mention concern over personal safety. In view of this, there is a growing emphasis on the prevention, early detection, and treatment of hearing loss. Although hearing aids suffice for many persons with hearing loss, a subset of the population with greater hearing loss may benefit from cochlear implantation, a relatively low-risk procedure that generally leads to improvements in speech understanding and quality of life. Yet it is estimated that only 10% of adults in the U.S. and other developed countries who meet the criteria for cochlear implantation actually receive it.

At least 1.2 million adults in the U.S. and 50 million worldwide are living with severe to profound hearing loss – a level of impairment that is not sufficiently corrected with hearing aids – and might benefit from cochlear implantation. The prevalence of hearing loss increases with age, and about 2/3 of people 70 and older have some degree of hearing loss. Also, that prevalence is likely to rise because, in the next 30 years, the proportion of the population 70 and over is likely to double. Here in the U.S., the most common causes of hearing loss in adults is recreational or occupational noise exposure, hereditary factors, and exposure to ototoxic medications (i.e. aminoglycoside antibiotics given intravenously in a hospital setting). The most common anatomical reason for hearing loss is damaged or missing hair cells located in the cochlea, which is found in the inner ear. The cochlea is an amazing, yet tiny and very sensitive organ. It is shaped like a snail’s shell and, by using the hair cells, it converts acoustic energy, or sound, into electrical signals which the brain interprets as sound, very similar to the retina in the eye which converts visual images into electrical signals which the brain interprets as vision.

Currently, there are no FDA-approved medications or surgical treatments that reverse hearing loss and restore normal hearing. While hearing aids may help allow a person to function reasonably well in a quiet environment, their use is limited in those with more severe hearing loss, especially if there is significant background noise. Hearing aids function by amplifying sound and, to work, they need to have functioning hair cells in the cochlea. Cochlear implants bypass nonfunctioning or missing hair cells and directly stimulate surviving spiral ganglion cells of the cochlear nerve, enhancing both audibility and speech recognition. A cochlear implant uses an external microphone, worn behind the ear like a hearing aid, to transmit a signal to an external transmitter. This transmitter overlies an implanted receiver-stimulator. An electrode runs from the implanted receiver-stimulator, through the mastoid bone (the hard, bony plate directly behind the ear), and terminates inside the cochlea. Implantation takes less than two hours and blood loss is minimal plus it is often done at outpatient surgi-centers.

There is a common misconception that the criteria for a cochlear implant is profound hearing loss. That is no longer the case as FDA labeling and rules have changed. If you or someone you know suffers from hearing loss not helped by hearing aids, get to your ENT specialist to find out if an implant is appropriate for you.

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By Peter Galvin, MD

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