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.
Imagine what it is like to be going about your daily routine when suddenly you hear a loud popping sound followed by intense pressure in your head, a ringing sound in your ears and feeling incredibly dizzy. How about waking up one morning and realising that you can’t hear in one ear? Perhaps you have a strange sensation that your ears feel full and clogged and your hearing suddenly deteriorates over a matter of days? This may sound like a nightmare, but it can be a frightening reality if you have sudden hearing loss.
As its name suggests, sudden sensorineural hearing loss (SSHL) or sudden hearing deafness happens suddenly and without warning. If that isn’t alarming enough, in many cases of sudden hearing loss, there’s no identified cause – this is known as idiopathic SSHL. SSH can vary in severity and can affect anyone, regardless of age, lifestyle or whether or not they have any history of ear problems. It usually only impacts one ear (unilateral) but around 1%-4% of SSHL cases involve both ears (bilateral), although it’s rare for both ears to be affected at the same time.
Symptoms of SSHL should never be taken lightly. Sudden hearing loss is considered a medical emergency, so if it happens to either yourself or a loved one, you need to seek medical help immediately. If you wait any longer than three days to get help, there may not be anything that can be done to help you. The sooner you act, the better prognosis you have for your hearing health.
The main signs that you have sudden hearing loss is an extremely loud ‘pop’ sound before your hearing suddenly decreases. You may experience a feeling of fullness in your ears or that they are clogged and your hearing rapidly decreases over a few days. A key indicator of SSHL is when your hearing has dropped to at least 30 decibels in 72 hours. You will find that despite people talking at a normal conversation volume, it now sounds like they are whispering. Other symptoms can include:
Although your hearing may have dramatically deteriorated in a very short amount of time, you may otherwise feel physically well and show no outward sign that anything is wrong. Your doctor or hearing care professional will, therefore, want to ask you several questions to find out more your symptoms, how long you’ve had SSHL and to what degree your hearing has dropped.
They will also likely ask you about your medical history and do a physical examination of the inside and outside of your ear to see if they can easily determine the cause, such as earwax clogging your ear. There are several tests that your doctor or hearing care professional may perform to try to decipher the cause of your sudden hearing loss.
Pure-tone audiometry: This test will measure your hearing threshold and is the main diagnostic tool to distinguish between conductive hearing loss and sensorineural hearing loss. Pure-tone thresholds are used to identify the softest audible sound you can hear at least half of the time. Your hearing sensitivity will then be plotted on a graph to show the intensity as a function of frequency – this is called an audiogram.
Speech-in-noise (SIN) testing: This enables your doctor or hearing care professional to assess your hearing in noisy surroundings. It helps in the measurement and evaluation of the functional capacity of your hearing system and is particularly effective in cases of single-sided deafness.
Otoacoustic emissions: This test involves inserting a small probe inside your ear canal to measure the soft vibrating sounds that occur when the outer hair cells located in your inner ear stimulated. If you have a blockage in your ear, then there will be no nerve responses.
Magnetic resonance imaging (MRI): MRI has become invaluable in providing insights into the potential causes of SSHL. Around 30%-50% of people with SSHL will have abnormalities show up on their MRI scans. Its high-resolution sequences can pick up subtle changes in the inner ear. It shows whether there is an unusual inflammatory patterns and asymmetry of the signal between the unaffected and affected sides.
Similar to regular sensorineural hearing loss, SSHL relates to damage to the auditory pathway located between the ear and brain or in the inner ear. If you have sudden hearing loss in both of your ears, the underlying cause for your sudden hearing loss could be one of more than 100. However, certain signs could indicate what has caused your SSHL. If you for instance experience repeated episodes of sudden hearing loss, it could be that the underlying cause relates to a primary neurologic disorder, bilateral Ménière’s disease or an autoimmune or metabolic disorder. Some of the other potential causes of SSHL include:
Inner ear disease: Ménière’s disease can cause incidences of SSHL, especially if you experience repeated episodes. This condition has been linked with abnormalities in the quantity, composition and at times the pressure of the fluid in the endolymphatic sac which is in your inner ear.
Viral infections: There has been evidence that viral infections can lead to sudden hearing loss. Some researchers believe that viral diseases and infections account for as many as 60% of SSHL cases. Viral-related hearing loss is likely caused by inflammation of the inner ear or auditory nerve, even though you may not experience any fever, pain or muscle cramps, which are common signs of a viral illness. Mumps is the only virus that experts have been able to definitively link to SSHL.
Bacterial infections: Two bacterial infections that are common causes of SSHL in some countries are Lyme disease and syphilis. Research has found that SSHL may relate to Borrelia burgdorferi infection, the principal bacteria that causes Lyme disease in certain regions. Otosyphilis, a complication of syphilis, has also been identified as causing sensorineural hearing loss, affecting one or both ears.
Autoimmune diseases: It’s become well documented that there is a link between Cogan syndrome, systemic lupus erythematosus and other autoimmune rheumatologic disorders and hearing loss. These account for around 4%-6% of SSHL cases.
Exposure to ototoxic drugs: There are at least 200 prescribed and over-the-counter medicines that are ototoxic and have hearing-related side-effects such as SSHL.
Medical procedures: Approximately one in 1,000 patients who undergo cardiopulmonary bypass are known to experience symptoms of SSHL. It’s unusual for SSHL to occur following the administration of general anaesthesia to patients undergoing non-cardiac procedures and surgeries that don’t involve the ear. Just 44 have so far been reported which have mostly occurred following abdominal, gynaecologic and ophthalmic procedures.
Blood circulation problems: Blood-flow change in the inner ear related to circulatory disorders has been a reported major cause of SSHL.
Coronary disease: While a study identified a connection between coronary risk factors and risk factors for SSHL, it didn’t show that high cholesterol is also a risk factor. A subsequent study of patients with high cholesterol found a 1.62 times greater incidence of SSHL among the group.
Tumours: Somewhere between 10%-20% of people with SSHL have a benign acoustic neuroma (vestibular schwannoma), while cerebellopontine tumours are a much rarer cause.
Multiple sclerosis (MS): While SSHL is a rare symptom of MS, it is two to 12 times more common in people with this disease compared to the wider population, according to a Finnish study.
Chronic stress and mental health issues: Stress is widely believed to be related to the onset of SSHL. A 2019 study found 81% of patients studied had higher-than-normal stress levels when admitted. But while being admitted to the hospital is a stressful time, researchers were able to conclude that these people in fact had higher levels of stress before the onset of SSHL than usual. A further study found high levels of mental problems (90%), and psychosomatic disorders (more than 70%) among people diagnosed with SSHL.
If doctors have been able to identify what has caused your specific case of SSHL, that will influence the treatment they recommend for you. In some incidences, SSHL will simply resolve by itself after a few weeks with no obvious explanation. But this should never be taken for granted. If you experience sudden hearing loss then you should get medical advice and treatment as soon as possible. The sooner you start treatment, the better your chance of making a good recovery. As there is often no identified cause in most cases of SSHL, treatments can vary. Some treatment options include:
Oral steroid therapy: This is a common treatment for SSHL. However, direct intratympanic injection of steroids into the middle ear is often more effective as the steroid medication can flow directly to the inner ear. You may find that you are given a course of high dose oral steroids which you will need to begin as soon as possible. Some people have reported an improvement in just the first 14 days of starting steroid treatment. However, as there can sometimes be certain side effects with taking steroids, you will need to be monitored while taking them.
A study that explored the potential use of a neuro-rehabilitation approach to treating SSHL discovered that sound therapy could offer a safe, easy, inexpensive and effective treatment. This treatment therapy involves people listening to music intensively through their affected hear. The treatment would need to be administered in a hospital, but it could offer a promising non-invasive treatment.
A woman with SSHL in her left ear was given a concentrated pharmacological treatment of high-dose oral corticosteroids over 17 days. Combined with pharmacotherapy, she was given 15 one-hour sessions each day of hyperbaric oxygen therapy to increase the level of oxygen in the inner ear fluids. While the woman initially experienced nearsightedness for around six days, she did report that she regained full hearing following the treatment.
How well you recover from SSHL will depend on your age, the severity of the hearing loss and the timeframe between symptoms starting and treatment starting. When treatment begins within the first 14 days after the onset of symptoms, around 80% of people will see some improvement, while others will recover their normal hearing. If you drink alcohol regularly or have a blood-vessel disease, you have a higher risk of poor hearing. So, improving your lifestyle and health will help considerably in your recovery.
While sudden hearing loss can be a frightening experience, getting treatment as soon as possible will give you better a chance of a quicker and better recovery. Delaying diagnosis and treatment can lead to a permanent loss of hearing. If you think you have sudden hearing loss or are worried about your hearing, schedule a consultation with a hearing care professional or your doctor and get the immediate treatment you need to protect your hearing health.
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