Sudden hearing loss

Your doctor will ask you about your symptoms, how long you’ve had them and their severity. They will also ask you questions about your medical history and carry out a physical examination to look for any obvious cause. The doctor will likely perform an audio-vestibular evaluation to help determine if your sudden hearing loss is linked exclusively to a problem in your inner ear. The types of test your doctor will likely want to carry out include:

• Pure-tone audiometry: This will assess your hearing threshold and is the key tool for diagnosing conductive and sensorineural hearing loss. Pure-tone thresholds will indicate the very softest audible sounds that 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 test will evaluate your ability to hear in noisy environments. This can help measure and evaluate the capacity of your hearing system, particularly with single-sided deafness.
• Otoacoustic emissions: A small probe-like device is inserted into your ear canal to measure the extremely soft vibrating sounds that are produced when the outer hair cells in the inner ear are stimulated. If there is no nerve response, then this indicates a blockage.

• Magnetic resonance imaging MRI: MRI scans are used to help identify the underlying cause of a person’s SSHL using high-resolution sequences which can detect subtle changes in the ear. They are also used to see if there is asymmetry of the signal between the affected and unaffected sides and any unusual inflammatory patterns.

SSHL is often linked to damage in the inner ear or auditory pathway between the ear and brain. When a person experiences sudden hearing loss in both ears, there could be more than 100 underlying causes. Certain symptoms can act as useful clues in helping to pinpoint what has caused a person’s sudden loss of hearing. If a person experiences repeated episodes of sudden hearing loss or experience it in both ears, the presumed causes are often bilateral Ménière’s disease, autoimmune or metabolic disorders or primary neurologic disorders.

• Inner ear disease: Ménière’s disease has been found to cause sudden hearing loss, especially repeated episodes of SSHL. It occurs following an abnormality in the quantity, composition and potentially the pressure of the fluid in the endolymphatic sac, which is a compartment in your inner ear.

• Viral infections: Researchers have found evidence of viral infections in individuals with sudden hearing loss. Some experts believe the viral disease is responsible for 60% of SSHL cases. Viral-related hearing loss is likely caused by inflammation of the inner ear or auditory nerve. In some cases, the person doesn’t experience pain, fever, muscle cramps, or any other signs of a viral illness. Mumps is the only virus that has definitively been tied to SSHL, and it is associated with other symptoms.
• Bacterial infections: Syphilis and Lyme disease have been found to cause some cases of SSHL. It’s believed that SSHL may coincide with Borrelia burgdorferi infection, the main bacteria that causes Lyme disease in certain countries. Otosyphilis, a complication of syphilis, has been found to cause sensorineural hearing loss, impacting either one or both ears.

• Autoimmune diseases: There’s a widely recognised link between Cogan syndrome, systemic lupus erythematosus, and other autoimmune rheumatologic disorders and hearing loss and account for around 4% to 6% of SSHL.

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

• Medical procedures: About one in 1,000 people who have cardiopulmonary bypass surgeries experience SSHL. Meanwhile, a smaller number of people experience SSHL after cervical spine manipulation.
• Blood circulation problems: Blood flow change in the inner ear related to circulatory disorders has been reported as a significant cause of SSHL.
• Coronary disease: A study has found a connection between coronary risk factors and risk factors for SSHL. Although this study didn’t show that high cholesterol was a risk factor, a larger study in 2014 found a 1.62 times greater incidence of SSHL in people with a higher than normal level of cholesterol.
• Tumours: About 10%-20% of people with symptoms of SSHL have a benign acoustic neuroma (vestibular schwannoma), while cerebellopontine tumours 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 compared to the general population, according to a Finnish study.

• Chronic stress and mental health issues: Stress has already been known to be a contributing factor to the onset of SSHL, a 2019 study found 81% of people experienced greater than normal stress when admitted. While it could be assumed this stress was linked to the person’s loss of hearing, it was concluded that people had higher levels of stress before the onset of SSHL than they usually experienced.

The treatment process for sudden hearing loss will largely depend on the cause. Some cases may simply resolve by themselves after a few weeks for no clear reason. But if you have symptoms of sudden hearing loss, you must get medical advice as soon as possible because the earlier the treatment the more likely you will have a better recovery. As such a high proportion of cases of SSHL don’t have a known cause, the treatment can vary. Some common treatment options include:

• Antiviral medications
• Systemic steroids
• Hyperbaric oxygen
• Vasodilators

Oral steroid therapy and direct intratympanic injection of steroids into the middle ear are becoming an increasingly common treatment. Injecting the steroid in this way allows the medication to flow from the middle ear to the inner ear. High-dose oral steroids are generally recommended to be taken as soon as possible, with people noticing an improvement during the first two weeks. People should be monitored during this treatment in case of any side effects of the steroids.

A study analysing the use of a neuro-rehabilitation approach to treating SSHL found that a new type of sound therapy used in hospitals could provide a safe, easy and effective treatment. This particular therapy motivates people to listen to music intensively through their affected ear while paying auditory attention to that ear.