Sudden deafness – or sudden sensorineural hearing loss – can occur for a number of reasons including viral infections and vaccinations. Sudden hearing loss usually occurs just in one ear, leading to problems hearing certain ranges of sound. You may notice it when talking on the phone or listening to music using headphones. Imagine that scary moment when you figure out that it isn’t a broken headphone and instead is due to hearing loss.
This article explains the current research on sudden sensorineural hearing loss, including links to viral and vaccine causes. Genetic variants can significantly increase your risk of sudden sensorineural hearing loss; knowing the genetic susceptibility leads to understanding why SSNHL occurs.
What is sudden sensorineural hearing loss?
Sensorineural hearing loss (SSNHL) is caused by damage either to the auditory nerve or to the tiny hairs in the cochlea.
Sudden sensorineural hearing loss, also called sudden deafness, is defined as hearing loss “greater than 30 dB in at least three consecutive frequencies that has developed within three days.”[ref] A hearing test can tell you if you’ve lost your hearing at certain frequencies.
It isn’t one of those ‘DIY’ types of health problems. If you think you have sudden hearing loss, head to the doctor because immediate treatment makes it more likely that you’ll recover your hearing.
About 50% of people with sudden sensorineural hearing loss do recover their hearing spontaneously. Usually, hearing recovery happens within a week or two.
The NIH includes the following as causes of sudden hearing loss:[ref]
- Viral infections.
- Head trauma.
- Autoimmune diseases.
- Exposure to certain drugs (e.g., chemo)
- Vascular issues
- Neurological disorders (e.g., MS)
- Disorders of the inner ear (e.g., Meniere’s disease).
What is behind SSNHL?
Genetic studies on SSNHL help to elucidate the root causes. The variants related to an increased susceptibility to SSNHL are in genes related to:[ref]
- endothelial dysfunction (blood vessel for the inner ear), and
- inflammation or oxidative stress in the inner ear
So what suddenly causes inflammation or blood vessel issues? There are several triggers:
Viral infections are a known cause of sudden sensorineural hearing loss. It is thought that epithelial inflammation in the blood vessels supplying the inner ear causes decreased blood flow to this delicate area.[ref]
- Measles and mumps are both long-known causes.[ref]
- Chronic rhinosinusitis[ref] and respiratory infections[ref]
Chronic diseases that cause vascular problems, such as type 2 diabetes, also increase the risk for SSNHL.[ref]
Sudden, really loud noise exposure can also lead to hearing loss. For example, exposure to sounds over 85 decibels can, over time, lead to hearing loss. Sudden exposure to really loud noise (like an explosion) can lead to sudden sensorineural hearing loss.
Chemotherapy drugs can also cause SSNHL due to high oxidative stress in the hair cells in the ears.[ref]
Vaccinations are also linked to SSNHL. Let’s dive into this further…
Vaccines and sudden hearing loss:
A report using data from the VAERS database from 1990 until 2003 showed that the live attenuated vaccines for measles and mumps were associated with 44 likely cases of hearing loss after immunization.[ref] Keep in mind that this study covered more than a decade of data, and the event rate was estimated to be 1 case per 6-8 million doses.
A case study reported sudden deafness after a rabies vaccine.[ref]
Several case studies and research studies have been published on sudden sensorineural hearing loss after COVID-19 vaccination. In fact, a report that adds together the published case studies shows about 1,200 case reports that physicians have written up. It does not include the reports in VAERS.[ref][ref][ref]
As of 1/7/2022, the VAERS database has over 2,000 reports of sudden hearing loss or deafness following COVID-19 vaccination.
A couple of things to keep in mind with VAERS statistics:
- First, it is unlikely that most people with hearing loss after the vaccine will report it to VAERS (who would think a vaccine could cause hearing loss?). Thus, it is likely that sudden hearing loss after vaccination is greatly underreported.
- Second, even if sudden hearing loss is underreported by 20-fold, with well over 200 million people receiving vaccinations this past year, hearing loss would still qualify as a rare side effect.
Inflammation in hearing loss:
I mentioned above that vascular dysfunction can cause hearing loss. It makes sense – when blood can’t reach the delicate depths of the ear, then the delicate parts of the inner ear can’t function properly.
The other causal factor in SSNHL is inflammation. Research shows that higher levels of inflammatory cytokines, such as interleukin 1 and TNF-alpha, are found in SSNHL. Inflammation ties to vascular dysfunction also, because it can cause swelling and vascular spasms.[ref]
Many of the genetic variants that researchers have identified for sudden hearing loss are in genes related to inflammation. For some people, genetic variants increase the inflammatory response – great for fighting off certain pathogens, but often a problem when overly active.
The two most common causes of SSNHL are autoimmune diseases or infections (viruses, syphilis). Both can cause a sudden increase in inflammation. The standard treatment for sudden hearing loss is corticosteroids, which reduce inflammation.[ref]
Heat shock proteins:
Heat shock proteins are activated by cells in response to a stressful condition, such as exposure to high heat. Heat shock proteins act as ‘chaperones’, a cell biology term meaning that they help stabilize or ensure the correct folding of other proteins under stress conditions. These resilience champions come alongside and help the other proteins needed in cellular function.
Resolving inflammation: An active process
The process of resolving inflammation is an active one, with anti-inflammatory molecules, such as resolvin, lipoxin, and maresin, being produced to actively resolve the inflammation. Pro-resolving mediators not only shut off the pro-inflammatory response but also are critical for clearing out the inflammatory waste products and restoring homeostasis. This is true for inflammatory processes throughout the body, such as heart disease, diabetes, rheumatoid arthritis… and hearing loss.[ref]
Researchers are now working to understand how to package and deliver pro-resolving mediators as a drug for curing SSNHL.[ref]
Genetic variants linked to sudden sensorineural hearing loss:
Genetic variants are linked to increased relative risk of sudden hearing loss. Let me give you an example to put this in perspective: If the normal risk of SSHL is 1 in 5,000, a variant that triples the risk puts your risk at 3 in 5,000. The genetic risk factors, though, give us a view into the role of infections, inflammation, and immune response. Not all variants associated with SSHL are included in 23andMe or AncestryDNA data.[ref]
Understanding where your genetic susceptibility lies may help you find the best treatment for you.
Endothelium dysfunction-related genetic variants:
EDN1 gene: encodes of vasoconstrictor peptide
Check your genetic data for rs5370 (23andMe v4; AncestryDNA)
- G/G: typical
- G/T: increased risk of sudden sensorineural hearing loss
- T/T: increased risk of sudden sensorineural hearing loss[ref]
Members: Your genotype for rs5370 is —.
F5 gene: encodes a clotting factor. The variant below is linked to an increased risk of blood clots.
Check your genetic data for rs6025 (23andMe v4, v5; AncestryDNA):
- C/C: typical
- C/T: one copy of factor V Leiden (read this article), increased risk of SSNHL
- T/T: two copies of factor V Leiden (read this article), increased risk of SSNHL[ref]
Members: Your genotype for rs6025 is —.
MTHFR gene: encodes an enzyme needed in using folate in the methylation cycle (important both in vascular health and in inflammation)
Check your genetic data for rs1801133 (23andMe v4, v5; AncestryDNA):
- G/G: typical
- A/G: one copy of MTHFR C677T allele, enzyme function decreased by 40%, increased relative risk of SSNHL
- A/A: two copies of MTHFR C677T, enzyme function decreased by 70 – 80%; increased risk of SSNHL[ref][ref]
Members: Your genotype for rs1801133 is —.
Inflammation-related variants linked to SSNHL:
SOD1 gene: encodes one of the cellular antioxidants responsible for reducing oxidative stress.
Check your genetic data for rs4998557 (AncestryDNA):
- A/A: increased relative risk of SSNHL[ref]
- A/G: typical risk
- G/G: typical
Members: Your genotype for rs4998557 is —.
IL1R2 gene: encodes a receptor for the proinflammatory cytokine, Interleukin 1
Check your genetic data for rs4141134 (AncestryDNA):
- A/A: typical
- A/G: increased relative risk of SSNHL
- G/G: increased relative risk of SSNHL[ref]
Members: Your genotype for rs4141134 is —.
UCP2 gene: mitochondrial uncoupling protein that is protective against free radicals in the inner ear
Check your genetic data for rs659366 (23andMe v4, v5; AncestryDNA):
- C/C: typical
- C/T: increased risk of SSNHL
- T/T: increased risk of SSNHL
Members: Your genotype for rs659366 is —.
IL6 gene: interleukin 6 (IL-6) is an inflammatory molecule that can be produced at the site of inflammation by macrophages.
Check your genetic data for rs1800796 (23andMe v4, v5; AncestryDNA):
- G/G: higher IL-6; increased risk of SSHL[ref] (common variant in many population groups)
- C/G: increased risk of SSHL
- C/C: typical
Members: Your genotype for rs1800796 is —.
HSP70 gene: heat shock protein 70 subunit
Check your genetic data for rs2763979 (23andMe v4, v5; AncestryDNA):
- C/C: typical
- C/T: typical risk of noise-induced hearing loss
- T/T: significantly increased risk of noise-induced hearing loss.[ref]
Members: Your genotype for rs2763979 is —.
CYP1A1 gene: encodes an enzyme used for detoxification
The CYP1A1*4 variant has a somewhat increased enzyme activity.
Check your genetic data for rs1799814 A2452C (23andMe v4, v5; AncestryDNA):
- G/G: typical
- G/T: one CYP1A1*4 allele; increased risk of SSNHL
- T/T: increased enzyme activity; CYP1A1*4[ref] increased risk of SSNHL[ref]
Members: Your genotype for rs1799814 is —.
It is definitely a situation where you should seek high-quality medical help from a specialist as quickly as possible. Time is of the essence in treating SSNHL, and earlier treatment is associated with a greater chance of getting your hearing back.
Below are research-based solutions that you can discuss with your hearing specialist.
Reduce inflammation: Corticoid steroids to reduce inflammation in the inner ear are usually the first line of treatment.[ref] This is why it is important to talk with your doctor as soon as you can.
Early hyperbaric oxygen therapy: A case study showed that the combination of hyperbaric oxygen therapy (along with the standard treatment of high-dose corticosteroids) was effective for full recovery of hearing. The patient was treated with 15 daily 1 hour exposures to 100% oxygen at 1.5 atmospheres absolute along with the corticosteroids.[ref] Multiple clinical trials also point to hyperbaric oxygen therapy along with corticosteroids as being statistically more effective than steroids alone.[ref][ref]
Dexamethasone in the ear: While systemic steroids are usually the first option for sensorineural hearing loss, another treatment option to talk with your hearing specialist about is intratympanic dexamethasone (injection of the steroid into the ear).[ref] A retrospective study found that intratympanic dexamethasone improved hearing in 40% of patients compared to only 13% in the control group of systemic steroids.[ref][ref]
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Debbie Moon is the founder of Genetic Lifehacks. Fascinated by the connections between genes, diet, and health, her goal is to help you understand how to apply genetics to your diet and lifestyle decisions. Debbie has a BS in engineering and an MSc in biological sciences from Clemson University. Debbie combines an engineering mindset with a biological systems approach to help you understand how genetic differences impact your optimal health.