April 28, 2021

Age Related Hearing Loss? Its Probably Presbycusis

Written by: Youssef Soliman, MBChB
Reviewed by: Mubashar Rehman, PHD

We all have seen older people wearing hearing aids, and I am sure you wondered why is that? Why some people require hearing aids as they age? This is presbycusis. Presbycusis refers to the progressive, irreversible hearing loss that happens to the elderly as they age.
Presbycusis medical definition is the degeneration of some ear structures responsible for converting sound waves to electrical signals sent to your brain. This is why some people may require hearing aids with age.
To understand the disease, let’s understand the structures of your ear and how they work.

A Journey to the Anatomy of the Ear

The ear consists of 3 parts: The external ear, the middle ear, and the inner ear.

 


BruceBlaus, CC BY-SA 4.0, via Wikimedia Commons

 

 

When you hear someone, the sound waves move inside the external ear. The sound waves will vibrate your eardrum. This will create vibrations that will vibrate structures inside your middle ear. Specifically, these structures are three bones: Malleus, incus, and stapes.
These bones will send their vibrations to your inner ear. Inside the inner ear, a structure called the cochlea will pick these vibrations and convert them to electrical signals to be transmitted to your brain. Here is how your cochlea looks like:

 

 

 

 

The cochlea sends signals to the brain. Here is a diagram that explains how signals are transmitted from external until it reaches your brain area responsible for hearing.

 

 


Zina Deretsky, National Science Foundation, Public domain, via Wikimedia Commons

 

 

Here is a video that explains how the process happens in more detail.

Presbycusis is a type of sensorineural hearing loss. In presbycusis, the cochlea becomes degenerated and damaged with time. This is different from the type of hearing loss you get when something is stuck inside your ear. This is called conductive hearing loss.

Causes of Presbycusis

The exact mechanism by which presbycusis happens isn’t completely understood. But it is believed to be related to multiple factors that combine in a genetically susceptible individual. Together, these factors may initiate presbycusis.

Here are some factors that can contribute to a hearing loss [1]:

Diabetes: Patients with diabetes are more likely to get thickening and narrowing of the blood vessels that supply the cochlea. This may lead to a reduced blood supply to the cochlea.

Hypertension: Hypertension also can lead to vascular changes that can compromise the blood supply to the cochlea.

Ototoxic drugs: Some drugs like aspirin may hasten presbycusis.

Atherosclerosis: Atherosclerosis refers to the deposition of blood lipids inside the wall of blood vessels, making them narrow, stiff, and less efficient in delivering blood to the cochlea. This condition is common in obese people, those who follow an unhealthy diet, and smokers.

The First Sign of Presbycusis

The first sign of presbycusis varies from person to person, depending on many factors like age and genetics. Nevertheless, here are some of the common symptoms related to presbycusis.

  • Inability to determine the direction of a sound
  • Difficulty understanding speech.
  • Requiring an increased volume of music or radio, which people might find annoying.
  • Sounds become muffled
  • You recognize ringing, tinnitus, hissings, and other sounds, but they aren’t present.

Three Common Presbycusis Types

There are three common types of presbycusis, although there are more of them, but they all ultimately result in degeneration of the cochlea and, thus, hearing loss. 

  • Sensory presbycusis: In this type, there is damage to the hair cells present in the cochlea. These hair cells are responsible for generating electrical signals to be sent to your brain. No hair cells mean no electrical signals, and, consequently, the patient can’t hear well. Here is how they look:

 

 

 

 

 

  • Neural: In this type, there is degeneration of the cells (called spiral ganglion) that receive electrical signals from hair cells. Again, this results in no signal being transmitted to your brain.
  • Metabolic: In this type, there is damage to a structure called stria vascularis. Stria vascularis is responsible for providing blood supply to your inner ear and maintain a proper chemical environment. 

As you can see, there are different types, but all lead to the same thing: hearing problems.

Presbycusis treatment

Presbycusis treatment is complex because it can’t be prevented or cured. Also, you need to be aware that there are no approved pharmaceutical drugs for this condition. Here are some of the available interventions:

Middle ear implants

Middle ear implants are surgically implanted hearing aids inserted into the middle ear. They work by amplifying the vibrations of the bony structures inside the middle, leading to enhanced signals.

Cochlear implants

In case your cochlea is severely damaged, your physician may recommend this procedure. It involves the placement of an electronic device that will replace your cochlea. 

Hearing aids 

Hearing aids work by amplifying sounds heard outside by an amplifier that sends the amplified signal to a speaker that will produce amplified sound into the ear.

Latest research trends

The current treatment options are limited. However, some experiments are taking place. Here is what does the research studies say:

A study done in 2010 found that supplementation with coenzyme Q10 (CoQ10) resulted in an improvement in preventing the development of hearing loss in volunteers with presbycusis [2].

Another animal study found an antioxidant therapy (comprised of L-cysteine-glutathione mixed disulfide, ribose-cysteine, NW-nitro-L-arginine methyl ester, vitamin B12, folate, and ascorbic acid) reduced age-related hearing loss in animal models [3]. Unfortunately, this study is contradicted by another study that showed that antioxidant therapy didn’t improve presbycusis mechanisms [4].

As we can see, we don’t know a lot about possible treatments for this condition. Hopefully, one day, we will be able to reach a drug that can stop the degeneration of the cochlea.

Conclusion

Presbycusis is a progressive sensorineural loss that happens due to age-related degeneration of the inner ear structure responsible for sound production. It is related to multiple factors, including genetics and chronic diseases like diabetes and hypertension. Unfortunately, so far, we don’t have medications that can stop or reverse the degeneration process. However, some studies found that some supplements may result in slowed degeneration. All these data are still in their beginning, and we can’t depend on them.

References

  1. Joo Y, Hong O, Wallhagen M (2016) The Risk Factors for Age-Related Hearing Loss: An Integrative Review. Ann Gerontol Geriatric Res 3(2): 1039
  2. Salami, A., Mora, R., Dellepiane, M., Manini, G., Santomauro, V., Barettini, L., &Guastini, L. (2010). Water-soluble coenzyme Q10 formulation (Q-TER(®)) in the treatment of presbycusis. Acta oto-laryngologica130(10), 1154–1162. https://doi.org/10.3109/00016481003727590
  3. Heman-Ackah, S. E., Juhn, S. K., Huang, T. C., &Wiedmann, T. S. (2010). A combination antioxidant therapy prevents age-related hearing loss in C57BL/6 mice. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery143(3), 429–434. https://doi.org/10.1016/j.otohns.2010.04.266
  4. Sha, S. H., Kanicki, A., Halsey, K., Wearne, K. A., & Schacht, J. (2012). Antioxidant-enriched diet does not delay the progression of age-related hearing loss. Neurobiology of aging33(5), 1010.e15–1010.e16. https://doi.org/10.1016/j.neurobiolaging.2011.10.023
Article written by Youssef Soliman, MBChB
Dr. Youssef Soliman has a deep passion for writing. He always loves to explain complex medical topics to laypeople. Youssef has over 1.6 Million views on his Quora account and thousands of followers who love to read his articles. He enjoys digging into the nitty-gritty of the most complex medical topics and come up with simplified, visual explanations for them. He also has interests in nutrition and biochemistry food because he believes that we are what we eat, and many diseases like heart disease are all related to what we eat and our lifestyle. This is why he wants to specialize to become an interventional cardiologist.

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