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Sudden deafness is severe or complete 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 deafness, 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 people each year develop sudden deafness. For hearing loss that develops gradually, see Hearing Loss.
Causes of sudden deafness fall into three general categories:
In most people, no cause can be found for their sudden deafness. 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.
In many other people, a cause for the sudden deafness 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 (see Some Causes and Features of Hearing Loss) 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.
A number of infections cause sudden deafness during or immediately after acute illness. Common 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.
Sudden deafness 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 deafness.
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.
The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.
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 deafness and the tests that may need to be done (see Some Causes and Features of Sudden Deafness).
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 Deafness
Typically, people should have an audiogram (a hearing test―see Testing). Unless doctors think the problem is clearly an acute infection or drug toxicity, they usually also do gadolinium-enhanced magnetic resonance imaging (MRI), particularly when the hearing loss is greater in one ear. Other tests are done based on the likely cause (see Some Causes and Features of Sudden Deafness). 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 is directed at any known cause of the sudden deafness. When the cause is unknown, many doctors try giving corticosteroids along with antiviral drugs effective against herpes simplex (such as valacyclovir or famciclovir).
When the cause is a viral infection or is unknown, about half of people regain normal hearing and the other half recover partial hearing. 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.
* This is the Consumer Version. *