It can happen without any warning. You might hear an extremely loud popping noise that grows quieter, followed by pressure in your head, ringing in your ears, and dizziness. Or you may simply wake up one morning and not be able to hear out of one ear. A third possibility is a feeling of fullness in your ear with gradual loss of hearing over a few days. Any of these scenarios is frightening and especially disconcerting when tests and exams don’t uncover an underlying cause.
Some degree of hearing loss is a common part of the aging process and many of us can expect to experience some amount of hearing loss as we get older. In most cases of hearing loss, over time a person’s hearing slowly reduces so they don’t always realize it’s happened. But what we don’t expect is to suddenly lose our hearing overnight. But this can happen to people with sudden hearing loss, regardless of their age.
Sudden hearing loss can happen without any warning. For some people, it starts with a very loud popping sound followed by pressure in their head, dizziness and ringing in their ears. They have suddenly lost their hearing in one ear for no obvious reason. Alternatively, they start to feel a strange fullness sensation in their ear and then over just a few days their hearing deteriorates. If that isn’t worrying enough, not everyone with sudden hearing loss will be able to discover the causes of it. The cause in many cases simply remains a mystery.
Sudden sensorineural hearing loss (SSHL) or sudden deafness can vary in severity and usually affects just one ear. But the effects can be frightening all the same. While around 1% to 4% of cases of SSHL affects both ears (bilateral), it’s very rare for it to involve both ears at the same time.
SSHL is so serious, it’s considered a medical emergency and if it should happen to you, you must seek immediate medical assistance. If you delay getting treatment longer than 72 hours, there’s a possibility that nothing that can be done to help you.
The popping in the ears sensation along with a sudden drop in hearing is a telltale sign that you have SSHL. You may find that your hearing drops by at least 30 decibels in just 72 hours. Normal conversations will now sound more like a whisper. Other symptoms include:
A basic physical ear examination is usually not enough to detect SSHL causes. Although it can sometimes be useful in ruling out certain causes such as an ear infection or impacted earwax which can result in hearing loss. Your hearing care professional or doctor will ask you questions about your symptoms and general health.
They will want to know how the sudden hearing loss started, your symptoms and how much of your hearing have you lost. They’ll also ask about your medical history and will likely want to do a physical examination of inside and outside your ear. They may also perform an audio-vestibular evaluation to see whether your case of SSHL can be linked to an issue in your inner ear.
SSHL testing
Diagnostic testing that may be carried out to determine the cause of your SSHL include:
Pure-tone audiometry: This test is designed to assess your hearing threshold. It’s the key diagnostic tool used by doctors to differentiate between sensorineural and conductive hearing loss. The pure-tone thresholds will reveal the softest sounds that you can hear for around 50% of the time. Your hearing sensitivity will then be plotted on a graph or audiogram which will show the intensity as a function of frequency.
Speech-in-noise (SIN) testing: This test allows your doctor to assess your hearing ability in noisy surroundings. It can be useful for measuring and evaluating the functional capacity of your hearing system and is particularly effective if you have single-sided deafness.
Otoacoustic emissions: A small device similar to a probe is put into your ear canal and will measure the very soft vibrating sounds that are produced when the outer hair cells in the inner ear become stimulated. If you have a blockage of some form, there will be no nerve response.
Magnetic resonance imaging (MRI): MRI has transformed the way certain complex conditions are diagnosed. It’s provided new insights about the varying underlying causes of SSHL thanks to its high-resolution sequences that detect very subtle changes in the inner ear. Doctors will be looking out for asymmetry of the signal between the affected and unaffected sides and whether there are any unusual patterns of inflammation. Around 30 to 50% of people with symptoms of SSHL will have some abnormalities that show up on their MRI scans.
Similar to regular sensorineural hearing loss, SSHL is linked to damage in the inner ear or auditory pathway between the brain and ear. If you experience sudden hearing loss in both of your ears, then it could be related to one of more than 100 causes. However, there are specific signs that can provide doctors and hearing care professionals with valuable clues about some potential causes. If a person has SSHL in both ears or has repeated episodes of sudden hearing loss it could be a result of an autoimmune or metabolic disorder, primary neurologic disorders or Ménière’s disease.
Known causes of SSHL
Inner ear disease: Ménière’s disease is a cause of SSHL, particularly when there is repeated episodes of sudden hearing loss. It is caused by abnormalities in the composition, quantity and sometimes pressure of the fluid in the endolymphatic sac in your inner ear.
Viral infections: Viral infections are believed to be a potential cause of SSHL and can be attributed to around 60% of SSHL cases. Hearing loss caused by viral-related hearing loss will likely have been caused by inflammation of the auditory nerve or inner ear. You may not even experience any pain, discomfort, muscle cramps or fever when you have it. However, mumps is the only virus has been confirmed as a definite cause of SSHL.
Bacterial infections: Two of the most common bacterial infections that have been found to trigger SSHL in certain countries are Lyme disease and syphilis. Studies have found that cases of SSHL may coincide with Borrelia burgdorferi infection, the primary bacteria that causes Lyme disease in some regions. Otosyphilis is a known complication of syphilis and can lead to sensorineural hearing loss and affects both ears, causing a sudden onset or rapid progression of symptoms.
Autoimmune diseases: It’s widely understood that there is a link between hearing loss and Cogan syndrome, systemic lupus erythematosus, and other autoimmune rheumatologic disorders. These are responsible for around 4% to 6% of cases of SSHL.
Exposure to ototoxic drugs: There are more than 200 medications available on prescription or over-the-counter which are ototoxic and have hearing-relating side effects such as SSHL.
Medical procedures: Around one in 1,000 people who have cardiopulmonary bypass surgery experience SSHL. Far fewer people experience SSHL following cervical spine manipulation. SSHL is relatively unusual after general anesthesia for non-cardiac procedures and surgeries that don’t concern the ear. Only 44 cases have been so far documented and most relate to gynecologic, abdominal, spinal, and ophthalmic procedures.
SSHL after dental procedures is very rare. However, a study reported on a case of a 79-year-old man who experienced acute hearing loss in his left ear and vertigo immediately after having a tooth extracted under local anesthesia. While vertigo did go the following day, his hearing loss remained. He was prescribed vasodilators, high-dose oral steroids, and vitamin B12 injections.
Blood circulation problems: A change in blood flow in the inner ear linked to circulatory disorders is a significant cause of SSHL.
Coronary disease: While a study found a link between the risk factors for SSHL and the risk factors for coronary problems, it didn’t show that high cholesterol was a contributing risk factor. Another larger study in 2014 that included people with high cholesterol found a 1.62 times greater occurrence of SSHL in this group.
Tumors: About 10 to 20% of people with SSHL have a benign acoustic neuroma (vestibular schwannoma), while cerebellopontine tumors are a much rarer cause.
Multiple sclerosis (MS): Although a rare symptom of MS, SSHL is two to 12 times more common in people with MS than the rest of the population, according to a Finnish study. In two of the 17 patients with MS and SSHL assessed in the study, SSHL was the first symptom of MS and for one, it was the only symptom.
Chronic stress and mental health issues: Stress is widely believed to be a risk factor for SSHL and this was supported by a 2019 study of 42 patients with SSHL. It was found that 81% reported greater than normal stress upon admission. An additional study showed there were greater psychological distress and more stressful life events in people with SSHL. Another study found high levels of mental health problems (90%), and psychosomatic disorders (more than 70%) in people diagnosed with SSHL.
As there are a variety of different causes for SSHL and sometimes the cause is never identified, there are several different options for treatment. However, in some cases, SSHL resolves itself relatively quickly on its own after just a few weeks with no obvious explanation. But if you do have symptoms of SSHL then you need to get medical advice immediately. The sooner you begin a treatment plan, the better your chance of making a good recovery.
Oral steroids are a common treatment for SSHL. However, direct intratympanic injection of steroids into the middle ear is particularly effective as it enables the medication to flow straight to the inner ear. It’s common for you to be advised to start a high dose of oral steroids immediately. This has been known to result in people reporting an improvement in only the first two weeks. There can be side effects of taking steroids, so you will need to be monitored by your doctor.
A study analyzing neuro-rehabilitation in the treatment of SSHL found that a new type of sound therapy could provide a safe, easy and effective treatment. This therapy encourages people to listen to music intensively through their affected ear while paying auditory attention to that ear.
A woman with SSHL in her left ear was given concentrated pharmacological treatment that comprised of high-dose oral corticosteroids over 17 days. Alongside pharmacotherapy, she was given 15 one-hour sessions of hyperbaric oxygen therapy each day to increase the level of oxygen in the inner ear fluids. While the woman reported that she experienced temporary nearsightedness for six days, she was able to regain full hearing afterwards.
Your recovery will largely depend on the underlying cause (which may not be identified), your age, the severity of your hearing impairment, but above all, how quickly you started treatment. If you start treatment straight away or at least within the first two weeks after symptoms begin, you could have a much better chance of seeing an improvement in your symptoms or even make a full recovery.
If you have any concerns about your hearing or hearing health or believe you may have SSHL then schedule a consultation with a hearing care professional or your doctor as soon as possible.
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