Sensorineural Hearing Loss – What’s It All About?

I was doing a little research online for my new website and was surprised to find that one of the most common search terms was: ‘what is sensorineural hearing loss’. This form of hearing loss is by far and away the most common; in fact, I can’t think of a single patient of mine that does not have sensorineural hearing loss at least to some degree, so I figured I’d write a post on it. Part of this material is taken from my book, Catching the Mind Robber. If you’d like a copy you can order via the link below.

I’ve decided to focus more on patient education via online channels, and one channel I’m starting to focus more on is Facebook. There you can find regular, informative content about hearing and brain health that I hope you’ll find worthwhile. What I like about Facebook is that I don’t need to bombard your email inbox every time there’s a useful piece of content to share! You can join simply via the following link:

https://www.facebook.com/Neuaudio/

Here’s more on all things sensorineural

Sensorineural hearing loss happens most often from damage to the receptor cells in the inner ear. We call them ‘hair cells’ however, I prefer the term ‘receptor cells’ as that’s essentially what they do. They convert movement and energy generated by sound waves into electrical impulses which, put simply, are the ‘language’ of the brain. Other causes of sensorineural hearing loss include damage to the auditory nerve or the brain; these are exceptionally rare, so we’ll focus here on the inner ear. This damage to the inner ear most commonly happens as you get older, but it also can happen because of noise exposure, chemotherapy, radiation, trauma and your genes.

What we’re primarily interested in when we consider sensorineural hearing loss of the inner ear is acquired age-related hearing lossand noise-related hearing loss. Eighty percent of hearing loss occurs in older adults, and a noise-induced component occurs in around half of cases. They are the most common, are permanent, and cause similar hearing loss configurations and similar symptoms. When both ageing and noise exposure are present, they combine to cause a relatively rapid decline in hearing sensitivity.

Sensorineural hearing loss is a progressive, degenerative disorder with neurological involvement. Noise exposure is very much like premature ageing of the hearing system; it simply speeds up the process.

The Cochlea – the organ of hearing

The cochlea, the specific structure in the inner ear that we’re interested in is also known as the ‘organ of hearing’ and has a finite number of receptor cells at the nerve endings that lead to the brain. These are referred to as inner and outer hair cells. The cochlea is roughly the size of a pea and contains around 30,000 receptor cells. The receptor or hair cells are the ear’s equivalent to the rods and cones of the eye; they receive stimulation from external sounds and pass along the information as a complex series of electrically charged neurochemical signals to hearing centres of the brain. As we age, we are genetically predetermined to endure the effects of hearing loss in a progressive and degenerative fashion.

With this progressive degenerative disorder, a gradual, continual loss and damage of receptor cells occurs within the cochlea. Each receptor cell has approximately 30 nerve fibres that are responsible for relaying information to the brain to process sounds, conversation, music and so on. The most delicate receptor cells are the ones that are stimulated by high pitch sounds, like the strings of a guitar or piano. High pitch strings and receptor cells are thin, fine and easiest to break. Consequently, people most commonly lose their hearing first in the high pitches. This often means they miss the higher pitch consonants that generally contain the meaning of words. This also causes havoc for most when trying to converse in background noise. This happens as each cell dies, along with the attached neurons.

Permanent damage, but something can be done to prevent further impairment

Sensorineural hearing loss in the inner ear is permanent and untreatable however the neural structures beyond the inner ear are responsive to treatment, provided it is delivered in time. My colleagues at Harvard and MIT tell me they are at least six years away from finding effective treatments that work specifically on the receptor cells of the inner ear. However, studies have shown that when appropriately fitted hearing aids are worn on a full time basis, we see both functional and structural improvements in the parts of the brain associated with hearing, speech, language and memory. Whilst there is no cure for sensorineural hearing loss, there are most certainly treatments thanks to the dynamic and ‘plastic’ nature of our brains. It is important to note that there is a window of opportunity for treatment to be effective, and effective treatment meansfull time use of hearing devices to achieve maximum stimulation.

I hope you’ve found this post useful, if you’ve not yet received a copy of my book, you can order one by going to www.neuaudio.com.au where you will see a pop-up for an instant ebook. Alternatively, you can go to www.abcbrainhealth.com.au/book to order a hard copy.

Best Regards

Andrew

ps. In case you missed it (!), to join our Facebook community (I really hope you do! 😉 ) please click on the following link:

https://www.facebook.com/Neuaudio/

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