The number of patients with “sudden deafness,” a condition in which a person suddenly loses the ability to hear sound for no particular reason, is increasing rapidly in Korea.

According to data from the Health Insurance Review and Assessment Service (HIRA), the number of sudden deafness patients increased by about 23 percent from 84,049 in 2018 to 103,474 in 2022, with patients in their 20s surging by more than 40 percent, from 8,240 to 11,557.

Some regain normal hearing with emergency treatment. However, one-third of patients only partially recover, and another third may not recover hearing, emphasizing the importance of emergency treatment. Korea Biomedical Review took a closer look at sudden deafness through an interview with Dr. Shim Dae-bo, professor of otorhinolaryngology at Myongji Hospital.

Question: What is sudden deafness?

Answer: As the name suggests, sudden deafness is a condition in which hearing loss occurs suddenly within a few hours to two to three days without any precursory symptoms. In many cases, it occurs without any specific cause, and it's classified as an emergency because the degree of hearing recovery depends on early treatment.

Q: At what level of inaudibility is sudden deafness diagnosed?

A: Normal hearing is considered to be between 0 and 20 decibels (dB), and a hearing loss of 30 dB or more in three or more consecutive frequencies on a pure tone audiogram is diagnosed as sudden deafness. It is usually unilateral and occurs at a hearing loss of 30 to 40 dB or more, the level at which a person cannot hear everyday conversation clearly.

Q: What causes sudden deafness?

A: There is no single cause. If the exact cause is not found after thorough testing, the condition is said to be idiopathic, which is the case in 80 to 90 percent of cases.

However, studies have suggested many possible causes, including inflammatory responses to viral infections, cochlear hypoxia due to vascular disorders, trauma, immune diseases, Meniere's disease, and tumors.

Q: What’s the reason for the surge of sudden deafness in the 20s?

A: As the cause of sudden deafness is unclear, we don't know exactly what is causing the surge in 20-somethings. However, it is speculated that factors such as exposure to loud noises, prolonged listening to high-pitched music through earphones, cell phone use, and stress and anxiety may be contributing factors.

Q: What are the symptoms of sudden hearing loss?

A: The most common symptoms are a sudden onset of tinnitus, a popping sound in the ear, or a feeling of fullness in the ears (tinnitus). About two-thirds of cases of sudden deafness are accompanied by tinnitus. So, if you suddenly experience tinnitus or ringing in the ears, you may have sudden hearing loss.

However, these are symptoms that everyone experiences at one time or another, so it's okay if they're short-lived, but if they last for more than half a day, you should see a doctor immediately.

Q: How is sudden hearing loss tested?

A: A basic medical history is taken, followed by an otoscopy and audiogram to determine the hearing loss's extent and rule out other causes.

Some patients present to the emergency room with symptoms of dizziness. Because it is difficult to perform an accurate hearing test right away in the emergency room, physicians may perform a simple emergency audiogram and treat it if sudden hearing loss is suspected. If a more accurate test is needed, physicians start treatment the next day in an outpatient setting.

Q: When is the ‘golden time’ to seek treatment? And how do specialists treat it?

A: Treatment should be sought no later than 14 days after the onset of symptoms. You can expect good results when treatment is started within three to seven days. If the hearing loss is mild, steroids are the only treatment. However, if the hearing loss is severe, a combination of steroids and hyperbaric oxygen therapy is recommended.

Steroid treatment is administered orally or intravenously through the tympanic cavity (tympanic membrane injection). However, patients with underlying medical conditions should be cautious as side effects of steroids can include increased blood sugar and blood pressure, hot flashes, edema, gastrointestinal upset, liver or kidney damage, and worsening of glaucoma.

In addition to steroids, some patients may be prescribed additional antiviral, vasodilator, or circulation-improving medications. Hyperbaric oxygen therapy delivers oxygen at a high pressure of more than two atmospheres to help restore hearing function by delivering high concentrations of oxygen to the body. The American Academy of Otolaryngology guidelines for sudden hearing loss also recommend it as an option, along with steroid treatment for severe hearing loss.

Q: What is hyperbaric oxygen therapy?

A: Hyperbaric oxygen therapy works on the principle that oxygen in the air is more soluble in body fluids under high pressure, increasing the oxygen concentration in the blood, allowing it to move around the body, and helping heal damaged areas. This principle is widely used to treat carbon monoxide poisoning in fire scenes and decompression sickness in divers.

Q: How long does hyperbaric oxygen treatment last? Are there any side effects?

A: Usually, after 10 treatments for two weeks, five times a week, we evaluate your hearing and check for side effects. Depending on the results, counseling is conducted to continue treatment for up to 20 sessions, and a final hearing evaluation is conducted to determine the direction of further treatment.

Hyperbaric oxygen therapy has fewer side effects because it uses no medication but only oxygen. However, it can cause ear pain due to the expansion of the eardrums at high pressure, and it isn't easy to use if there is a pneumothorax.

Q: Isn't it expensive to combine steroids and hyperbaric oxygen therapy?

A: In cases of sudden deafness with an initial hearing loss of 80 dB or more, hyperbaric oxygen therapy can be covered by insurance, which can reduce the financial burden.

Q: What if you missed the “golden time” for treatment?

A: If you didn't seek treatment early on, or if your hearing doesn't improve for more than three months after treatment, it can be difficult to restore your hearing. At this point, hearing rehabilitation with aids should be considered. Depending on the severity of the hearing loss and tinnitus, there are various hearing rehabilitation methods, such as hearing aids, CROS or BICROS hearing aids, bone canal implants, and cochlear implants.

Q: Is there any way to prevent sudden hearing loss?

A: There are no specific preventive measures, but you can practice habits that reduce ear fatigue. The World Health Organization (WHO) recommends using portable sound devices at no more than 60 percent of their maximum volume and for no more than 60 minutes per day to protect your hearing.

It would help if you also avoided or reduced your intake of alcohol, tobacco, and coffee, which can irritate the nerves in your ears and affect blood vessel constriction. If this is not possible, having your ears checked regularly with a hearing test is a good idea.