A key problem with SSHL is that it is often invisible to anyone other than the person affected. When you go to your doctor, hospital or hearing care professional you might not have any other physical symptoms and otherwise may look and feel fit and healthy. SSHL cannot be detected by just a basic physical ear examination alone, although this can help to rule out certain potential causes such as a build-up of earwax or ear infection which could affect hearing.

Your doctor or hearing care professional will ask you a series of questions to find out more about your symptoms and overall health. They will likely ask how long you’ve had the sudden loss of hearing and much has your hearing deteriorated.

They’ll also need to know about your medical history and will also want to do a physical examination of your ear to see if it’s possible to spot an obvious cause. They may likely perform audio-vestibular evaluation which will help them to ascertain whether your sudden hearing loss is associated with an issue in your inner ear.

Diagnostic testing

Pure-tone audiometry: This test will assess the threshold of your hearing and is the main diagnostic tool to assess your hearing threshold and to distinguish between sensorineural and conductive hearing loss. Pure-tone thresholds will be able to determine the softest audible sound you can hear at least 50% of the time. Your hearing sensitivity will then be plotted on a graph called an audiogram which will show intensity as a function of frequency.

Speech-in-noise (SIN) testing: This is a useful test that will evaluate how well you hear in noisy surroundings. It can help with evaluating and measuring the functional capacity of your hearing system and is particularly effective if you have hearing loss in one ear or single-sided deafness.

Otoacoustic emissions: A small probe-like device is put into the ear canal and this will measure the very soft vibrating sounds that are produced when there is stimulation to the outer hair cells in the inner ear. If the test shows no nerve response, this indicates that you have a blockage in your ear.

Magnetic resonance imaging (MRI): MRI technology has transformed the way hearing conditions are diagnosed and treated. The high-resolution sequences can detect subtle changes in the inner ear and show any asymmetry of the signal between the affected and unaffected sides and whether there are any unusual inflammatory patterns.

Just like with regular sensorineural hearing loss, SSHL relates to damage to the inner ear or the auditory pathway between the ear and the brain. Although sudden hearing loss in both ears is less common, there are around 100 potential underlying causes that could be responsible for SSHL. For instance, if someone experiences a sudden hearing loss in both ears or recurring episodes of sudden hearing loss, primary neurologic disorders, bilateral Ménière’s disease or autoimmune or metabolic disorders could be the underlying cause.

Inner ear diseases: Ménière’s disease has been linked with causing SSHL, especially when a person has repeated SSHL episodes. It is thought to occur as a result of irregularities in the quantity, composition and sometimes pressures of the fluid in the endolymphatic sac which is a section in the inner ear.

Viral infections: Some people with sudden hearing loss have been found to have a viral infection at the same time. Experts believe that viral diseases can account for up to 60% of SSHL cases. Viral-related hearing loss is likely to have been caused by inflammation of the inner ear or auditory nerve. In some cases, a person may not be aware that they have a viral infection as they don’t feel any pain, fever or muscle cramps. Mumps is the only virus that has been found to have a definite link to SSHL.

Bacterial infections: Lyme disease and syphilis are known to cause SSHL in some countries. There have been studies that suggest SSHL could coincide with Borrelia burgdorferi infection, which is the main bacteria responsible for causing Lyme disease in certain regions. Otosyphilis is a complication of syphilis and has been identified as a cause of sensorineural hearing loss that can impact one or both ears and cause a sudden onset of symptoms.

Autoimmune diseases: It’s widely accepted that there’s a link between Cogan syndrome, systemic lupus erythematosus, and other autoimmune rheumatologic disorders to hearing loss. It accounts for roughly 4%-6% of cases of SSHL.

Exposure to ototoxic drugs: More than 200 medications are ototoxic, which means they have hearing-related side effects, including SSHL.

Medical procedures: Somewhere around one in 1,000 people who have cardiopulmonary bypass experience SSHL, while far fewer people experience SSHL after receiving cervical spine manipulation. It’s unusual for SSHL to occur after a person has had general anesthesia for non-cardiac procedures and any surgeries that don’t involve the ear. Just 44 cases have so far been documented and these have mainly been following spinal, gynaecologic, ophthalmic and abdominal procedures.

Blood circulation problems: Blood flow change in the inner ear related to circulatory disorders is considered to be a major cause of SSHL.

Coronary disease: A study found a link between coronary risk factors and risk factors for SSHL. Although this study didn’t show that high cholesterol was a risk factor, another larger study in 2014 found a 1.62 times greater occurrence of SSHL in this group.

Tumours: About 10 to 20% of people with SSHL have been found to have a benign acoustic neuroma (vestibular schwannoma).

Multiple sclerosis (MS): Although it’s generally considered a rare symptom of MS, SSHL is two to 12 times more common in people with MS than the general population, according to a Finnish study.

Chronic stress and mental health problems: A 2019 study on 42 patients with SSHL found 81% of people reported higher-than-normal stress when they were admitted. Although it could be assumed that this stress was entirely related to them losing their hearing, it was concluded that these individuals had higher stress levels before their SSHL symptoms started than they would usually experience. A separate study found that people with SSHL had greater levels of psychological distress and experienced more stressful life events.

Treatment for sudden hearing loss will depend on what caused it if that can be determined. Some cases of SSHL will resolve on their own after a few weeks without any intervention for no obvious reason. But anyone with symptoms of sudden hearing loss should get medical advice as soon as possible. The earlier they receive treatment, the better the chance they will have at making a full recovery. As most cases of SSHL don’t have a known cause, treatments for it can vary. Some options for treatment can include:

• Antiviral medications
• Systemic steroids
• Vasodilators
• Hyperbaric oxygen

While oral steroid therapy is widely used to treat SSHL, direct intratympanic injection of steroids into the middle ear is particularly effective as it enables the medication to flow directly from the middle ear to the inner ear. It’s usually recommended that people start taking a high dose of oral steroids as soon as possible. When this happens, many people have reported an improvement in their symptoms in just the first two weeks. As there can be some side effects with steroids, the individual will need to be monitored during the treatment process.