Everyone's hearing naturally declines with age, and people often have one ear that hears better than the other. But if hearing loss appears suddenly in one ear for no apparent reason, you may have experienced sudden sensorineural hearing loss, or SHL, a kind of nerve deafness.
There are about 66,000 new cases of SHL per year in the United States, according to research in the August 2019 issue of Otolaryngology — Head and Neck Surgery. But these numbers are hard to come by, since the condition may be underdiagnosed.
"The main reason is that people don't view it as a serious problem and don't get the medical care they need. This delay increases the risk of permanent hearing loss," says Dr. Steven Rauch, an Ear, Nose and Throat specialist with Harvard-affiliated Massachusetts Eye and Ear.
It is not known what causes SHL, but experts point to several possible reasons: a viral infection, an immune system malfunction, an inflammatory injury to the ear, or blocked blood flow to the ear — or even some combination of these.
SHL can affect people of all ages, although it tends to occur most in the 50s and 60s. It usually strikes one ear. You may hear a "pop" or feel like your ear is clogged. "Your hearing often does not go away all at once, either," says Dr. Rauch. "It is a gradual decline over several minutes or even hours, like air leaking from a tire."
Besides hearing problems, SHL can affect your balance, which increases your risk of falls. SHL also could be a sign of a small stoke or tumor. SHL gets ignored because the symptoms feel familiar, like a head cold or earwax or water in the ear. People try to treat it with cold or sinus medicine, swimmer's ear drops, or cleaning their ears. "They think it's just an annoying stuffy ear that will go away, so they put it on the back burner until it's too late," says Dr. Rauch.
| How can you know the difference between a regular stuffy ear and sudden hearing loss? Try this test: Hum aloud to yourself. With normal hearing, you hear the sound equally in both ears. If you do this when you have a new loss of hearing in one ear, the humming will shift to one side or the other. For example, if your right ear is affected and the hum is louder in that ear, then the hearing loss is more likely a conductive loss, and probably due to blockage from a cold or built-up ear wax. (You can simulate this effect by humming while you cover your right ear.) However, if the humming is louder in the left ear, it suggests the right ear hearing loss is due to recent nerve damage, and that requires prompt medical attention. |
But time is of the essence to save your hearing. "You have about a 10- to 14-day window to treat SHL; otherwise the hearing loss becomes permanent," says Dr. Rauch. "So make sure to see your doctor, or get a referral to visit an ear, nose, and throat specialist if your hearing goes away for longer than a day."
However, even with timely treatment, you may not regain your full hearing. "In most cases, mild SHL may recover, but people with moderate or severe hearing loss make a total recovery only in about 20% of cases, even with prompt treatment," says Dr. Rauch.
SHL is treated with corticosteroids over a two- to three-week period. You can take the drugs orally or via an injection through the eardrum. Corticosteroid pills, such as prednisone, are taken at the same dose every day for 14 days, and then the dose tapers off for the final week. Alternatively, ear injections are given twice a week for two weeks.
Oral steroids are more comfortable to take but can have side effects like an upset stomach, higher blood pressure, mood swings, and insomnia. Injections generally have no systemic side effects, but they can be uncomfortable, and people have to visit their doctor to get them. Some doctors recommend both oral and injected steroids in hopes of increasing the recovery rate.
"Remember that if you are used to normal hearing and it suddenly blocks up, that is never okay," says Dr. Rauch. "The sooner you get it checked out, the better. If it is SHL, every day you delay reduces your chance of recovery."
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Sudden sensorineural (“inner ear”) hearing loss (SSHL), commonly known as sudden deafness, is an unexplained, rapid loss of hearing either all at once or over a few days. SSHL happens because there is something wrong with the sensory organs of the inner ear. Sudden deafness frequently affects only one ear.
People with SSHL often discover the hearing loss upon waking up in the morning. Others first notice it when they try to use the deafened ear, such as when they use a phone. Still others notice a loud, alarming “pop” just before their hearing disappears. People with sudden deafness may also notice one or more of these symptoms: a feeling of ear fullness, dizziness, and/or a ringing in their ears, such as tinnitus. (For more information, read the NIDCD fact sheet Tinnitus.)
Sometimes, people with SSHL put off seeing a doctor because they think their hearing loss is due to allergies, a sinus infection, earwax plugging the ear canal, or other common conditions. However, you should consider sudden deafness symptoms a medical emergency and visit a doctor immediately. Although about half of people with SSHL recover some or all their hearing spontaneously, usually within one to two weeks from onset, delaying SSHL diagnosis and treatment (when warranted) can decrease treatment effectiveness. Receiving timely treatment greatly increases the chance that you will recover at least some of your hearing.
Experts estimate that SSHL strikes between one and six people per 5,000 every year, but the actual number of new SSHL cases each year could be much higher because SSHL often goes undiagnosed. SSHL can happen to people at any age, but most often affects adults in their late 40s and early 50s.
What causes sudden deafness?
A variety of disorders affecting the ear can cause SSHL, but only about 10 percent of people diagnosed with SSHL have an identifiable cause.
Some of these conditions include:
- Infections.
- Head trauma.
- Autoimmune diseases.
- Exposure to certain drugs that treat cancer or severe infections.
- Blood circulation problems.
- Neurological disorders, such as multiple sclerosis.
- Disorders of the inner ear, such as Ménière’s disease. (For more information, read the NIDCD fact sheet Ménière’s Disease.)
Most of these causes are accompanied by other medical conditions or symptoms that point to the correct diagnosis. Another factor to consider is whether hearing loss happens in one or both ears. For example, if sudden hearing loss occurs only in one ear, tumors on the auditory nerve should be ruled out as the cause. Autoimmune disease may cause SSHL in one or both ears.
How is sudden deafness diagnosed?
If you have sudden deafness symptoms, your doctor should rule out conductive hearing loss—hearing loss due to an obstruction in the ear, such as fluid or ear wax. For sudden deafness without an obvious, identifiable cause upon examination, your doctor should perform a test called pure tone audiometry within a few days of onset of symptoms to identify any sensorineural hearing loss.
With pure tone audiometry, your doctor can measure how loud different frequencies, or pitches, of sounds need to be before you can hear them. One sign of SSHL could be the loss of at least 30 decibels (decibels are a measure of sound intensity) in three connected frequencies within 72 hours. This drop would, for example, make conversational speech sound like a whisper. Patients may have more subtle, sudden changes in their hearing and may be diagnosed with other tests.
If you are diagnosed with sudden deafness, your doctor will probably order additional tests to try to determine an underlying cause for your SSHL. These tests may include blood tests, imaging (usually magnetic resonance imaging, or MRI), and balance tests.
How is sudden deafness treated?
The most common treatment for sudden deafness, especially when the cause is unknown, is corticosteroids. Steroids can treat many disorders and usually work by reducing inflammation, decreasing swelling, and helping the body fight illness. Previously, steroids were given in pill form. In 2011, a clinical trial supported by the NIDCD showed that intratympanic (through the eardrum) injection of steroids was as effective as oral steroids. After this study, doctors started prescribing direct intratympanic injection of steroids into the middle ear; the medication then flows into the inner ear. The injections can be performed in the offices of many otolaryngologists, and are a good option for people who cannot take oral steroids or want to avoid their side effects.
Steroids should be used as soon as possible for the best effect and may even be recommended before all test results come back. Treatment that is delayed for more than two to four weeks is less likely to reverse or reduce permanent hearing loss.
Additional treatments may be needed if your doctor discovers an underlying cause of your SSHL. For example, if SSHL is caused by an infection, the doctor may prescribe antibiotics. If you took drugs that were toxic to the ear, you may be advised to switch to another drug. If an autoimmune condition caused your immune system to attack the inner ear, the doctor may prescribe drugs that suppress the immune system.
If your hearing loss is severe, does not respond to treatment, and/or happens in both ears, your doctor may recommend that you use hearing aids (to amplify sound) or even receive cochlear implants (to directly stimulate the auditory connections in the ear that go to the brain). For more information, read the NIDCD fact sheets Hearing Aids and Cochlear Implants.
What research does the NIDCD support on sudden deafness?
Since so little is known about the causes of most cases of SSHL, researchers are considering different types, risk factors, and causes of SSHL. For instance, researchers are studying how changes in the inner ear, such as disrupted blood flow or inflammation, may contribute to hearing loss. Researchers are also testing new ways to use imaging to help diagnose SSHL and potentially detect its causes.
NIDCD-funded researchers are also trying to improve ways of dispensing drugs into the inner ear by intratympanic injections. Scientists are developing ways to infuse drugs into tiny microspheres that can slowly release the drug. This would allow doctors to give a single injection of a slow-releasing drug into the ear rather than several injections of a traditional fast-releasing drug. Another team of scientists is studying the use of magnets to push drug-infused particles into and throughout the inner ear, distributing the drug more evenly and effectively. Visit the NIH Clinical Research Trials and You website to read about these and other clinical trials that are recruiting volunteers.
The NIDCD maintains a directory of organizations that provide information on the normal and disordered processes of hearing, balance, taste, smell, voice, speech, and language.
For more information, contact us at:
NIDCD Information Clearinghouse 1 Communication Avenue Bethesda, MD 20892-3456 Toll-free voice: (800) 241-1044 Toll-free TTY: (800) 241-1055