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Sudden Hearing Loss

By Lawrence R. Lustig, MD, Howard W. Smith Professor and Chair, Department of Otolaryngology–Head and Neck Surgery , Columbia University Medical Center and New York Presbyterian Hospital

Sudden hearing loss is moderate to severe hearing loss that develops over a few hours or is noticed on awakening. Such hearing loss typically affects only one ear (unless the cause is a drug). Depending on the cause of sudden hearing loss, people may have other symptoms such as ringing in the ears (tinnitus), dizziness, or a false sensation of spinning or moving (vertigo). About 1 in 5,000 to 1 in 10,000 people each year develop sudden hearing loss. For hearing loss that develops gradually, see Hearing Loss.

Causes

Causes of sudden hearing loss fall into three general categories:

  • An unknown cause

  • An obvious explanatory event (such as a brain infection or head injury)

  • An underlying disorder

Unknown cause

In most people, no cause can be found for their sudden hearing loss. However, doctors have several theories. Possible causes include viral infections (particularly infections with herpes simplex virus), an attack on the inner ear or its nerves by the body's immune system (autoimmune reaction), and blockage of the small blood vessels of the inner ear or the blood vessels of its nerves. Perhaps different causes affect different people.

Obvious event

In many other people, a cause for the sudden hearing loss is obvious. Such causes include

Head injury (such as a fracture of the temporal bone in the skull or sometimes a severe concussion without a fracture) can damage the inner ear and cause sudden hearing loss.

Severe pressure changes (such as those that can occur with diving or less often by bearing down during weightlifting) can cause a hole (fistula) to form between the middle and inner ear. Sometimes, such a fistula is present from birth and can spontaneously cause sudden hearing loss or make the person more susceptible to hearing loss after a head injury or pressure changes.

Ototoxic drugs are drugs that have damaging side effects to the ears. Some drugs can rapidly cause hearing loss, sometimes within a day (especially with an overdose). A few people have a rare genetic disorder that makes them more susceptible to hearing loss from the class of antibiotics called aminoglycosides. In fact, people receiving drugs that are excreted in the urine, such as aminoglycosides, should have their kidney function checked and monitored while on the drug to avoid toxic levels in the blood that can cause hearing loss.

A number of infections cause sudden hearing loss during or immediately after acute illness. These infections include bacterial meningitis, Lyme disease, and many viral infections. The most common viral causes in the developed world are mumps and herpes simplex brain infection. Measles is a very rare cause because most people are immunized against the infection.

Underlying disorders

Sudden hearing loss rarely can be the first symptom of some disorders that usually have other initial symptoms. Such disorders include a tumor of the auditory nerve called acoustic neuroma, multiple sclerosis, Meniere disease, or a small stroke of the balance center of the brain (the cerebellum). Sometimes a syphilis infection reactivates in people who have HIV infection. This reactivation can cause sudden hearing loss.

Rarer disorders include Cogan syndrome, in which an autoimmune reaction attacks the inner ear (and also the surface of the eye); certain disorders involving blood vessel inflammation (vasculitis); and blood disorders such as Waldenström macroglobulinemia, sickle cell disease, and some forms of leukemia.

Evaluation

The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.

Warning signs

Sudden hearing loss is itself a warning sign.

When to see a doctor

Anyone with sudden hearing loss should see a doctor right away because some causes must be treated quickly. If symptoms of dysfunction of the nervous system other than hearing loss are present, hearing loss may be a symptom of nerve or brain dysfunction.

What the doctor does

Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination may suggest a cause of the sudden hearing loss and the tests that may need to be done (see Some Causes and Features of Sudden Hearing Loss).

Doctors note whether hearing loss affects one or both ears and whether a specific event such as head injury, diving injury, or infectious illness occurred. They ask about accompanying symptoms that involve the ear (such as ringing in the ears or ear discharge), balance center (such as disorientation in the dark or vertigo), and other parts of the brain and nervous system (such as headache, weakness, or an abnormal sense of taste). They try to identify whether people are currently taking (or recently took) any ototoxic drugs.

The physical examination focuses on the ears and hearing and on examination of the nervous system.

Some Causes and Features of Sudden Hearing Loss

Cause

Common Features*

Tests

Unknown

Deafness in only one ear

No other symptoms

Audiogram

MRI using a contrast agent (gadolinium)

Obvious causes

Acute infection (such as bacterial meningitis, Lyme disease, mumps, or herpes simplex)

Deafness in one or both ears

In people with a serious, acute illness

Often headache and confusion

With Lyme disease, deafness preceded by a typical rash and flu-like symptoms

With mumps, pain in cheeks with swallowing

A doctor's examination

If not already done, blood tests and a spinal tap (lumbar puncture)

Audiogram

Deafness usually in only one ear

Sometimes fluid (bloody, blood-tinged, or clear) coming from the affected ear

Audiogram

CT and/or MRI

Pressure changes (as may occur during diving)

Deafness in one or both ears

Sudden onset during causative activity

Sometimes accompanied by an explosive sound, dizziness, or ringing in the ear

Audiogram

Tympanometry (placement of a device in the ear to measure how well sound passes through the ear)

Electronystagmography (a test to record involuntary movements of the eye caused by a condition known as nystagmus)

CT or MRI

Drugs that can damage the ear (ototoxic drugs), including

  • Aspirin

  • Aminoglycosides (such as gentamicin and tobramycin)

  • Vancomycin

  • Cisplatin

  • Furosemide

  • Ethacrynic acid

  • Quinine

Deafness in both ears

Sometimes dizziness and loss of balance

In people who recently started taking an ototoxic drug

A doctor's examination

Audiogram

Hidden disorders

Acoustic neuroma (a tumor of the auditory nerve)

Deafness in only one ear

Often dizziness or a false sensation of spinning or moving (vertigo) and loss of balance

Sometimes drooping facial muscles and/or numbness of the face and taste abnormalities

Audiogram

MRI using a contrast agent (gadolinium)

Autoimmune disorders, such as some blood disorders, disorders that cause vasculitis, and Cogan syndrome

Deafness in one or both ears

Sometimes joint pains or a rash

Audiogram

Blood tests

Deafness in only one ear in about three fourths of people

Sometimes dizziness and/or ringing in the ear

A doctor's examination

Audiogram

MRI using a contrast agent (gadolinium)

Deafness in only one ear

Sometimes weakness or numbness that comes and goes and that occurs in different parts of the body

Audiogram

MRI using a contrast agent

Sometimes a spinal tap

Stroke (affecting the cerebellum)

Deafness in only one ear

Sometimes difficulty with balance or coordination

Audiogram

MRI using a contrast agent

Reactivation of syphilis in people with HIV infection

Deafness in one or both ears

Sometimes risk factors for sexually transmitted diseases (such as unprotected sex, multiple partners)

Audiogram

Blood tests

Sometimes, spinal tap (lumbar puncture)

*Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. Features overlap between causes.

All people should have an audiogram.

Rarely, sudden hearing loss is the first symptom of a disorder that usually has other symptoms first. Symptoms typical of these disorders may not be present at all. However, some people disregard mild symptoms that may be discovered by the doctor through careful questioning and examination.

CT = computed tomography; MRI = magnetic resonance imaging.

Testing

Typically, people should have an audiogram (a hearing test). Unless doctors think the problem is clearly an acute infection or drug toxicity, they usually also do gadolinium-enhanced magnetic resonance imaging (MRI) or computed tomography (CT), particularly when the hearing loss is greater in one ear. Other tests are done based on the likely cause. For example, people who had a head injury should have MRI. People at risk of sexually transmitted diseases should have blood tests for HIV infection and syphilis.

Treatment

Treatment is directed at any known cause of the sudden hearing loss. When the cause is unknown, many doctors try giving corticosteroids along with antiviral drugs effective against herpes simplex (such as valacyclovir or famciclovir), even though there is no good evidence that antiviral drugs are beneficial.

When the cause is idiopathic (unknown), about half of people regain normal hearing and hearing is partially recovered in others. Improvement, if it can be achieved, usually occurs within 10 to 14 days. Recovery from an ototoxic drug varies greatly depending on the drug and the dosage. With some drugs (such as aspirin and diuretics), hearing returns within 24 hours. However, antibiotic and chemotherapy drugs often cause permanent hearing loss if safe dosages have been exceeded.

Key Points

  • Why sudden hearing loss occurs is usually unknown.

  • A few people have an obvious cause (such as severe head injury or infection or use of drugs that can damage hearing).

  • In a very few people, sudden hearing loss is the first sign of an underlying disorder.

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