OVERVIEW

What is sudden deafness?

Sudden deafness, also known as sudden sensorineural hearing loss (SSNHL), refers to an abrupt hearing impairment caused by dysfunction in the organs responsible for receiving or processing auditory information.

The condition has numerous potential causes, including infections, acoustic neuromas, trauma, medications, autoimmune disorders, and impaired blood supply to the inner ear. However, the exact cause remains unidentified in most patients.

Treatment targets the identified underlying cause when possible. If the cause is unknown, empirical therapies such as corticosteroids and hyperbaric oxygen therapy may be used.

The disease has a tendency toward spontaneous recovery, with some patients regaining varying degrees of hearing without intervention. Younger patients generally have better prognoses. Severe hearing loss or accompanying vertigo at diagnosis may indicate poorer outcomes.

Is sudden deafness common?

Sudden deafness is not rare, with an incidence of approximately 5 to 20 cases per 100,000 people annually. It can occur at any age but is most prevalent in individuals aged 50–60. Recent years have seen increasing cases among younger patients. No significant gender difference in incidence has been observed.

SYMPTOMS

What are the symptoms of sudden deafness?

Sudden deafness is primarily characterized by abrupt hearing loss.

Patients typically experience hearing decline to its lowest point within minutes, hours, or one to two days (usually around 12 hours, not exceeding 72 hours). Pure-tone audiometry, a common ENT examination, reveals hearing loss ≥ 30 dB in at least three consecutive frequencies. It may be accompanied by tinnitus, ear fullness, dizziness, nausea, or vomiting, but symptoms do not recur.

The condition can be classified into six types based on pure-tone audiometry results: low-frequency, mid-frequency, high-frequency, flat-type, total deafness, and others.

What adverse effects (complications) can sudden deafness cause?

The disease primarily affects hearing and may involve tinnitus, ear fullness, dizziness, nausea, or vomiting. Underlying causes may also trigger other symptoms, such as fever or unsteady gait.

Can sudden deafness lead to complete hearing loss?

The condition progresses rapidly upon onset, often reducing hearing to its lowest point within a day. Severe cases may result in total deafness.

CAUSES

What are the causes of sudden deafness?

Sudden deafness can be caused by various factors, but the cause remains unknown in most patients.

Viral neuritis or cochleitis due to viral infection may be the most common cause, followed by meningitis, syphilis, and HIV/AIDS, which can also manifest as sudden deafness.

Tumors, trauma, or damage to the inner ear or auditory nerve may also lead to sudden deafness.

Certain ototoxic drugs can cause sudden deafness, such as aminoglycoside antibiotics (including streptomycin, gentamicin, etc.), erythromycin, and anticancer drugs (e.g., vincristine, cisplatin).

Some autoimmune diseases like Cogan syndrome, systemic lupus erythematosus, temporal arteritis, and polyarteritis nodosa may also be associated with sensorineural hearing loss.

Occlusion of the internal auditory artery—the blood supply to the inner ear—can result in sudden deafness. Additionally, psychological factors like emotional trauma may also be linked to the onset of the condition.

Who is more prone to sudden deafness?

The high-risk population is not clearly defined, as anyone can be affected. Middle-aged and elderly individuals, as well as those with autoimmune diseases, syphilis, or HIV/AIDS, may have an increased likelihood of developing the condition. Cold exposure or a history of emotional trauma may also contribute to its onset in some patients.

DIAGNOSIS

What tests are needed to diagnose sudden deafness?

The diagnosis of this disease is mainly based on medical history, combined with pure tone audiometry for clinical classification.

However, to further investigate possible causes of sudden deafness and provide targeted treatment, additional imaging and laboratory tests—such as infectious disease screening, rheumatologic tests, and ear imaging—may be required depending on the patient's condition.

Why is pure tone audiometry performed for sudden deafness? What precautions should be taken during the test?

Pure tone audiometry measures the faintest sounds a patient can hear at different frequencies, serving as a standard behavioral test for hearing sensitivity.

This test helps differentiate sensorineural hearing loss from easily confused conductive hearing loss. Additionally, if hearing loss ≥ 30 dB occurs in three or more consecutive frequencies, combined with medical history, it can confirm a diagnosis of sudden deafness. Clinicians can also use the results to classify the type of sudden deafness and assess its severity.

The test is non-invasive and painless but requires patient cooperation. Before the test, remove earwax blockages, glasses, headwear, and hearing aids. Follow the doctor's instructions—respond immediately (by pressing a signal button or raising a finger) upon hearing faint tones and stop responding when no sound is heard. Each ear is tested separately.

The accuracy of the results depends on cooperation between the patient and the doctor. Patients should respond promptly to even the faintest sounds.

Which diseases are easily confused with sudden deafness? How to distinguish them?

This condition must first be differentiated from diseases causing conductive hearing loss. The primary methods for distinction include detailed medical history and tests such as pure tone audiometry or auditory evoked potentials.

TREATMENT

Which department should I visit for sudden deafness?

Otolaryngology (ENT).

Does sudden deafness require treatment? Can it heal on its own?

Treatment is necessary. Although the condition has a tendency to self-resolve in some cases, with a minority of patients recovering spontaneously, active treatment significantly improves recovery rates. Additionally, it is important to rule out potential underlying causes such as tumors, infections, immune disorders, or vascular blockages.

Early treatment is crucial, as the timing of intervention affects recovery chances. Starting treatment within 7–10 days of onset generally yields better outcomes.

Does sudden deafness require hospitalization?

Hospitalization is usually necessary for observation, treatment, and screening for potential underlying causes.

How is sudden deafness treated?

Treatment includes addressing the underlying cause and empirical therapy.

• Cause-specific treatment: Depending on the identified cause, targeted therapies are used. For infections, antibiotics or antivirals are prescribed; tumors may require surgery or other interventions; drug-induced toxicity calls for discontinuing ototoxic medications alongside neuroprotective, microcirculation-improving, or hormonal treatments.
• Empirical therapy: For cases with unclear causes, the following approaches may be used:
  • Corticosteroids: High-dose prednisone is administered initially, followed by tapering, typically over a 10-day course.
  • Hyperbaric oxygen therapy (HBOT): This involves breathing pure oxygen in a pressurized environment to increase inner ear oxygen levels, showing some clinical efficacy.
  • Circulation-improving and antiviral treatments: While the 2006 Chinese guidelines endorse these, the 2012 American guidelines do not recommend them.

What are the common side effects of medications for sudden deafness?

Corticosteroids, the recommended empirical treatment, require caution due to contraindications (e.g., infections, glaucoma, peptic ulcers with bleeding, uncontrolled hypertension/diabetes). Side effects may include gastrointestinal bleeding, hypokalemia, weight gain, fluid retention, and osteoporosis.

Can sudden deafness be completely cured? How long does treatment take?

Since the cause is often unclear, recovery time and outcomes vary. Early treatment improves prognosis, but some patients may not fully regain pre-onset hearing levels.

• For idiopathic cases, 1/3 to 2/3 of patients may partially recover within 2 weeks; those with >50% improvement in this period have better outcomes.
• Patients with minimal improvement in the first 2 weeks are unlikely to recover significantly.
• Recovery for identified causes depends on the specific condition.
• Younger patients and early-treated cases have higher recovery rates.

Is follow-up needed after recovering from sudden deafness?

A follow-up at an ENT clinic after 6 months is recommended, including pure-tone audiometry.

Can sudden deafness recur?

There is a chance of recurrence.

What if treatment for sudden deafness fails?

For incomplete recovery, hearing aids or assistive devices may be used. Intratympanic steroid injections could be considered, though clinical evidence is limited.

DIET & LIFESTYLE

What should patients with sudden deafness pay attention to in their diet?

A low-sodium diet helps reduce possible endolymphatic hydrops, so it is important to maintain a low-salt diet while avoiding irritating foods. Eat more fruits and vegetables, and maintain a balanced diet with reasonable portions of meat and vegetables.

What should patients with sudden deafness pay attention to in daily life?

Avoid catching cold, staying up late, and overexertion, and refrain from traveling to high-altitude areas. For those with poor hearing recovery, it is necessary to adjust their mindset, maintain emotional stability, stay positive, and actively manage chronic conditions such as hypertension, diabetes, and rheumatic immune diseases.

PREVENTION

How to Prevent Sudden Deafness?

Due to the diverse causes of this condition, prevention methods for sudden deafness vary depending on the underlying mechanisms.

• For sudden deafness caused by occlusion of the internal auditory artery, actively managing chronic conditions such as hypertension, hyperlipidemia, and diabetes—which contribute to atherosclerosis—can reduce the risk of onset;
• For sudden deafness related to rheumatic immune diseases or tumors, proactive treatment and control of the primary disease can help prevent occurrence;
• For sudden deafness associated with trauma, medications, or infections, avoiding injuries, refraining from ototoxic drugs, and preventing cold exposure or excessive fatigue can lower the risk;
• For idiopathic sudden deafness with unknown causes, there are no effective preventive measures, but maintaining a positive mood and a regular, healthy lifestyle may still be beneficial.