Sensorineural Hearing Loss: Symptoms, Causes & Treatments 2023

Here’s an amazing fact! Did you know that you are born with around 16,000 hair cells^[1] within your cochlea? These tiny cells are so powerful that they can enable you to hear the cries of your firstborn, an enchanting dawn chorus, or the voice of your beloved spouse. Cool right?

Right. However, sensorineural hearing loss will affect as much as 65% of us by the time we are 60, robbing us of this most treasured ability! Worse, up to 30-50% of those 16,000 cells might be completely destroyed before we notice hearing loss!

So what can we do? Thankfully, if we stay vigilant, we can protect this most valuable resource long into old age. Read on to find out how. We’ll be defining sensorineural hearing loss, exploring common causes, symptoms, and diagnostic approaches, and explaining, finally, how it can be successfully treated.  

According to the National Institute on Deafness and Other Communication Disorders,  almost 30 million people^[4] in the U.S. alone over the age of 12 years have hearing loss in both ears. However, it is important to note that not all hearing loss is sensorineural. 

There are, in fact, two types of hearing loss. Conductive hearing loss can occur in the case of an injury or blockage that prevents sound from reaching the inner ear. Conversely, sensorineural hearing loss^[5] is caused by damage to the inner ear, cochlea, related structures, or the vestibulocochlear nerve. 

When it comes to conductive versus sensorineural hearing loss, it is crucial to make the distinction as to which is causing hearing issues (as both require different pathological and treatment-focused options). We’ll focus on sensorineural causes of hearing loss in this article, given that it constitutes the vast majority of cases.

Sensorineural Hearing Loss Symptoms

If you’re worried about hearing loss, what should you look for? According to the National Institute on Aging,^[12] common symptoms and examples of sensorineural hearing loss usually include:

1. Struggling to hear people clearly on the telephone (with hearing loss experienced in one affected ear or both).
2. Experiencing difficulty in following a conversation when at least two people are talking. Needing to ask friends, family, or colleagues to frequently repeat themselves.
3. Requiring a higher television volume to the point that others complain about its loudness. Finding that background noise makes it difficult for you to listen to what someone is saying to you. Thinking that others are mumbling when they are, in fact, speaking at a normal volume. Not being able to hear properly when people with higher-pitched voices (e.g., young children) are speaking or not detecting high-pitched sounds.
4. Suddenly experiencing tinnitus or associated symptoms (a ringing or buzzing sound in the ears).

It is important that you consult with a doctor as soon as the hearing loss occurs, as early detection of hearing issues can often significantly improve treatment outcomes, especially in the case of sudden onset^[13] hearing loss, profound sensorineural hearing loss, unilateral hearing loss, fluctuating hearing loss, or sudden deafness.

Sensorineural Hearing Loss Causes

What causes hearing loss? It’s a great question.

A sensorineural hearing loss diagnosis can be attributed to a wide range of factors, relating to the onset of certain diseases and medical conditions, congenital issues, genetic syndromes, the effects of aging, and noise pollution. For example, hearing loss is a lesser-known side-effect of meningitis^[14] and diabetes.^[15] Interestingly, twice the incidence of hearing loss has been observed amongst diabetics. 

It can also be caused by Meniere’s disease^[16] (a disorder that displays a core phenotype of sensorineural hearing loss, tinnitus, and episodic vertigo). In the case of barotrauma,^[17] a difference in pressure within the body can cause physical tissue damage, which can, in turn, damage hearing.

Vestibular schwannoma are benign tumors^[18] that can cause sensorineural hearing loss. These tumors can cause hearing loss by secreting substances that are possibly damaging to the cochlear nerve or inner ear and/or by compressing parts of the nerve or artery attached to it. 

Causes of sensorineural hearing loss can also be related to existing autoimmune conditions, such as Muckle-Wells syndrome. In the case of Muckle-Wells, systemic and organ-specific inflammation occurs due to the excessive release of interleukin-1, often resulting in inner ear inflammation and potentially irreversible sensorineural hearing loss. 

Another known cause is a perilymphatic fistula^[19] (i.e., abnormalities that arise between the perilymph-filled inner ear and the intracranial, or middle ear, cavity) or a head injury.

Work And Age-Related Hearing Loss

Frequently, sensorineural hearing loss can be caused by occupational noise exposure and noise trauma at work. In fact, the Centers for Disease Control and Prevention cite statistics^[8] that 22 million Americans are exposed to hazardous noise levels every year. These hazardous levels can cause ear damage, destroying the inner ear’s tiny hairs, harming the outer ear’s hair cells, and damaging the eardrum. 

A further 30 million workers may be exposed to ototoxic^[9] chemicals (chemicals that can damage the ear) every year. Both noise exposure and ototoxic chemicals can cause sensorineural hearing loss. Jobs that require heavy noise exposure include construction, shipping, and steelwork.

Presbycusis, a medical term relating to sensorineural hearing loss caused by age-related degeneration,^[20] remains a common cause of hearing loss. In fact, one in three people^[10] over the age of 65 will experience age-related sensorineural hearing degeneration. And finally, congenital defects (medical conditions that we are born with) can also lie at the root of our hearing issues.

How Is Sensorineural Hearing Loss Diagnosed?

According to the World Health Organization, hearing impairment is diagnosed as^[21] falling across one of five potential severity grades, which relate to the severity of hearing loss in the better ear (i.e., the ear that one can hear most effectively from). These severity grades constitute no, slight, moderate, severe, and profound. The World Health Organization considers a severe impairment to reflect a pure-tone threshold^[22] of 61-80 decibels Hearing Level (61-80 dB HL).

This diagnosis differs slightly from that of the European Working Group of Genetics of Hearing Impairment, which calculates gradings of hearing impairments on a metric known as the four-frequency pure-tone average^[23] of an individual’s better ear. Using this metric, hearing impairments recorded at grades II to IV are considered to be disabling.

As with any medical condition, early detection and diagnosis can lead to improved outcomes for the patient. According to the World Health Organization,^[24] a hearing loss diagnosis can be made via the use of the following tests and examinations: The following tests and examinations, as set up by WHO, identifies various forms of hearing loss:

• Otoscopic examinations, which identify common outer and middle ear problems. 
• Otoacoustic tests^[25] assess inner ear response to sound (this can be done when the patient is asleep or awake).
• Tympanometry assesses middle ear function and diagnoses nonsuppurative otitis media. 
• Otoacoustic emission testing. These tests are most often used amongst preschool-age children or children with special needs, who may be unable to respond to other behavioral hearing tests because of their age.
• Tests conducted by an ear, nose, and throat doctor (otolaryngologist), an eye doctor (ophthalmologist), or a geneticist, depending on the cause of the hearing loss.

Innovative testing solutions have recently been made available to wider populations, including the hearWHO hearing loss screening app,^[26] created by the World Health Organization, which is available for download to a smartphone. 

When diagnosing longer-term or sudden hearing loss, a doctor can specify a mild, moderate, or severe level. The severity of the loss is related to the number of decibels that an individual can no longer hear. Mild hearing loss represents a loss of hearing between 26-40 decibels. Moderate hearing loss is classified as hearing loss that occurs between 41 – 55 decibels, and severe hearing loss is more than 71 decibels.

A sensorineural hearing loss audiogram^[27] will then be used to quantify and visually display a patient’s level and nature of hearing loss.

What Are The Treatment Options?  

The most widespread treatment options^[28] for moderate and profound hearing loss are based on the use of medical devices following a hearing test (e.g., sensorineural hearing loss hearing aids, cochlear implants for the inner ear) rather than pharmaceutical therapies of any kind. 

These treatment options include^[29] assistive listening devices, for example, amplified sounds (particularly useful when a lot of background noise is present) and alerting devices. The latter connects to a telephone, alarm, or doorbell using a loud noise or light, making it easier for the user to know when someone is trying to contact them. 

These devices can be used alongside a cochlear implant, an electronic device that is surgically implanted in the cochlea of the inner ear. It converts sounds to electronic impulses, which are then interpreted by the brain, enabling some individuals with severe hearing loss to effectively hear sounds again. Cochlear implants are effective in cases of bilateral sensorineural hearing loss as well as unilateral sensorineural hearing loss. 

In the longer term, with over 100 genetic loci^[28] recently linked to hearing loss in academic studies, gene therapy appears to offer a potentially new and promising innovation in the treatment of sensorineural hearing loss. Similarly, Platelet-rich Plasma^[7]-focused treatments may also offer some positive benefits.

The Bottom Line

Some of the greatest men and women in history were, in fact, deaf. Ludwig van Beethoven, one of the most talented musicians in modern history, experienced profound deafness^[30] throughout his life but remained active as a composer and conductor. Renowned inventor Thomas Edison lived with unilateral hearing loss,^[31] while world-famous human rights campaigner Helen Keller was profoundly deaf (and blind). 

Despite these inspiring stories, temporary or permanent hearing loss remains the most common^[28] form of sensory impairment in humans and can seriously blight our quality of life. According to the Global Burden of Disease Study, it is thought that around 1.4 billion^[2] people currently experience hearing loss, with serious hearing loss potentially occurring before we’ve even noticed it. So chances are, it might well affect us, or someone we love, one day.

Given these insights, there has never been a better time to prioritize our hearing. It is, without doubt, a valuable resource that we cannot afford not to protect! 

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