Asymmetrical Sensorineural Hearing Loss

Experts say that approximately 466 million people in the world suffer from disabling hearing loss. That is about 6.1% of our world’s population-- which is a lot. This number is actually said to be even higher but most of those with hearing loss go without seeking help because they overwrite their hearing problems as allergies or sickness, or they just get used to it. This is why it’s so important to fully understand what hearing loss is, and all the different types there are. But first, what is hearing loss? Well, an individual who is not able to hear thresholds of 20 decibels (dB) or higher in one or both of their ears is considered to have hearing loss. Hearing loss can be mild, moderate, severe, or profound. There are many different categories/types of hearing loss-- all of which can be read about on our Audien Hearing blog-- but this article will focus solely on Asymmetrical sensorineural hearing loss.

WHAT ASYMMETRICAL HEARING LOSS?

Hearing loss gradually increases in each ear over time, this is called symmetrical hearing loss. Asymmetrical hearing loss on the other hand, is when one ear has worse hearing when compared to the other. When an individual has hearing loss, the hearing loss is never usually the same in both ears. To be considered asymmetrical hearing loss, the difference between the two ears has to be 15 dB or higher at a number of frequencies. On top of this, the hearing loss must be bilateral-- a hearing loss in both ears.

The causes of asymmetrical hearing loss are typically the same for hearing loss in general:

  • Aging
  • Genetics
  • Hearing related diseases
  • Prolonged asymmetry exposure to loud noise

Asymmetrical hearing loss can be conductive hearing loss, sensorineural hearing loss, or mixed hearing loss.

WHAT IS SENSORINEURAL HEARING LOSS?

Sensorineural hearing loss (or SHL) means that either the stereo-cilia (tiny hair cells in the inner ear) are damaged or there is a problem with the inner ear nerve pathways leading to your brain. SHL is most commonly a bilateral hearing loss, though it can occasionally be a unilateral hearing loss. SHL is a lifelong hearing loss once it is developed and can make soft sounds difficult to hear or loud sounds unclear. 

Some signs/symptoms include:

  • Dizziness or balance issues.
  • Difficulty hearing high-pitched noises. 
  • Difficulty hearing sounds amid background noise.
  • Sounds and voices seem to be unclear or muffled.
  • Feeling like you can hear people talking but you cannot understand them.

It affects roughly 9 out of 10 individuals with hearing loss, making it one of the most common types of hearing loss. To find out more about sensorineural hearing loss, click here.

ASYMMETRICAL SENSORINEURAL HEARING LOSS

Asymmetrical sensorineural hearing loss (or ASHL) is an asymmetrical hearing loss that is of the sensorineural hearing loss category. Thus, it is a combination of both, which is atypical and can be difficult to treat. 

CAUSES OF ASHL

Asymmetrical sensorineural hearing loss can occur due to any of the common causes of bilateral sensorineural hearing loss. This includes but is not limited to noise related hearing loss and age related hearing loss. Nevertheless, it can also be a result of more serious issues: 

  • A symptom of vestibular schwannoma or an intracranial tumor
    • Vestibular schwannoma (also known as acoustic neuroma) is a benign tumor, often occurring in those in their mid 40’s, from the Schwann cells in the vestibular part of the cranial nerve. It’s origin is typically the internal auditory canal and grows to the cerebellopontine angle of the posterior cranial over time. This tumor makes up more than 85% of all cerebellopontine angle tumors, though it occurs in only about 2% of patients with ASHL. This is the reason your ENT doctor may request an MRI if you have ASHL. If you have vestibular schwannoma, your case is more severe, calling for treatments more complex than just hearing aids. Management of the tumor depends on the size of the tumor, your symptoms, and your personal preferences/medical history. Typical treatment includes radiation or surgery. In many cases, hearing cannot be restored, but the tumor can be prevented from causing more problems such as balance issues or facial weakness to name a few.
  • An underlying pathological problem such as an immune disorder 
  • Meniere’s disease or idiopathic sensorineural hearing loss
    • Meniere’s disease is an inner-ear condition that can cause vertigo-- a dizziness that makes you feel like you are spinning, tinnitus, and ear pressure. Typical treatment is medications, however in some cases which do not respond to medications, surgery can be offered.

Sometimes it can be hard to pinpoint the exact cause of ASHL, but a hearing care professional can help by examining your ears and discussing your medical/background history.

TREATMENT OF ASHL

The first step in diagnosing asymmetrical sensorineural hearing loss is to make an appointment with your doctor. Seeing your primary care physician and later an ENT doctor and an audiologist about your ASHL can help rule out the presence of tumors that need to be treated, show implications for other family members where an inherited cause is identified, or simply provide a cause and explanation that may or may not be specifically treatable. ASHL does not automatically mean there is something bad like an acoustic tumor.

In cases where ASHL can be treated, the most common treatment is hearing aids. The goal with hearing aids is to get the patient with ASHL to have binaural hearing again, hearing sounds through both ears as a unified sound. Though, this cannot always be the outcome.

There are different levels of asymmetrical hearing loss:

  • Hearing loss in both ears, one ear is better
  • In this case both ears individually are likely candidates for hearing aids. Though, there is still a functional difference between the ears so the amount of amplification in ear ear will be different based on your hearing tests. 

  • One ear is deaf, one ear has some hearing loss
  • Individuals with one deaf ear and one ear with some hearing loss are typically candidates for cochlear implants. However, if they choose not to get implants or their doctor advises against it, they can get a hearing aid. In this case, their ear with some hearing loss will be doing all of the work hearing-wise. Though, a hearing aid may not be the most feasible option. 

  • One ear is normal, one ear has some hearing loss
  • This is surprisingly one of the most difficult cases to help with hearing aids. This is because once given a hearing aid, the ear with hearing loss will mix sounds with the normal acoustic hearing from the other side of the head.  Meaning, hearing can become more sensitive in the ear with a hearing aid. Many people with this situation often need to be patient. In the long-run, many find that the hearing aid does help for many situations and to locate where sounds are coming from or sound localization.

    CONCLUSION

    Asymmetrical sensorineural hearing loss is not only a mouthful to say but also a very challenging hearing disability to deal with. It is a mix between two complicated hearing loss scenarios-- asymmetrical hearing loss and sensorineural hearing loss. Its causes are similar to those of general bilateral hearing loss and it can’t always be treated. However, when it can be treated, the most common and effective treatment has proven to be hearing aids. If after reading this article, you think you may have some symptoms relating to ASHL, it is crucial to make an appointment with your doctor as soon as possible.

    If you find that you are suffering from asymmetrical hearing loss, sensorineural hearing loss, or both, be sure to check out our high-quality and affordable hearing aids at Audien Hearing!


    Thanks for reading, and here's to better hearing!

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    Drew Sutton M.D.

    Drew Sutton, MD is a board-certified otolaryngologist. He has extensive experience and training in sinus and respiratory diseases, ear and skull base surgery, and pulmonary disorders. He has served as a Clinical Instructor at Grady Hospital Emory University for more than 12 years.

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