Causes Of Sudden Hearing Loss
Dr. Luca Vassalli
Chief of otolaryngology at Kaiser Permanente
Where did you receive your schooling and training?
I received my undergraduate and medical degrees from the University of California-Davis, and completed my residency at the University of Illinois-Chicago.
How long have you been practicing?
I’ve been practicing as an otolaryngologist (ear, nose and throat physician) for 24 years.
Is sudden hearing loss fairly common?
Yes, it is common. We probably see about one patient a month with this condition.
What causes sudden hearing loss?
Nobody really knows. Some of the more likely causes are inner ear infections – viral infections of the hearing nerve, also called the acoustic nerve, which goes from the inner ear to the brain. The second possibility is a small vascular clot in the internal auditory artery, which provides the blood supply to the inner ear. Other less common causes would be a sudden change in barometric pressure in the inner ear – for example, resulting from diving or the quick loss of pressure experienced when flying in an airplane. A rare cause can be a tumor, which arises in the vestibular nerve located right next to the acoustic nerve. This tumor will cause pressure on the acoustic nerve and, although rare, can cause sudden hearing loss. In all patients, we recommend conducting an MRI imaging of the brain to exclude the possibility of such a tumor being there.
Are any of these forms of hearing loss preventable?
Sudden hearing loss related to a change in barometric pressure can be prevented by avoiding high-risk activities such as diving and skydiving. As far as the more likely causes of sudden hearing loss – a viral infection, for instance – there is no way to prevent it. A quick onset of hearing loss is not preventable in most cases.
What treatment options are available?
Most physicians recommend a one-week course of corticosteroid, which is a powerful anti-inflammatory. Most otolaryngologists would recommend a high dose of a corticosteroid drug, like prednisone; a high dose would be 60 milligrams a day of prednisone for about a week. Although there is no proven scientific evidence that shows that corticosteroids actually help, treating sudden hearing loss with corticosteroids is common practice among otolaryngologists. The treatment has to be administered within two to four weeks of the actual onset of hearing loss. If it has been longer than one month since the onset of hearing loss, it has been shown that this treatment protocol will not work. There can be some spontaneous improvement in hearing loss without treatment, but we don’t know what the percentage is versus the people who have been treated with steroids.
Some otolaryngologists also recommend an injection of a corticosteroid in the middle ear, especially if the oral treatment has not helped.
As with any other medications, there are some risks associated with prednisone, especially in patients with diabetes, hyper-tension or other chronic illness. In these patients, the injection may be preferable to oral treatment, as one can administer a smaller amount of the drug closer to the target organ. More research is necessary, however, before we can be certain that the injection actually works.
Are the symptoms irreversible if the problem is not immediately addressed?
Not necessarily. There are a fair number of patients who will get better even without treatment. We don’t know what the percentage is, but it does happen. You would need a very large randomized study, which has not been done to date, to tell what percentage of patients get better without treatment. However, the stakes are too high to not treat patients.
Are there similar conditions, and how do those present and respond differently?
If sudden hearing loss is caused by a tumor, it would not respond to corticosteroid treatment. Slower onset loss such as hearing loss caused by aging also will not respond to this treatment.
What distinguishes sudden hearing loss from an infection or other conditions is the absence of pain or discharge from the ear. Sudden hearing loss can be accompanied by ringing or dizziness, but it’s never accompanied by ear pain or discharge.
Are there times when sudden hearing loss is permanent and can’t be treated?
Yes. I would say that if it’s a case of severe, total hearing loss, the chances of hearing coming back are smaller than it is with a milder hearing loss. Even though we treat everyone with a corticosteroid within two to four weeks of the onset of hearing loss, it doesn’t always mean that treatment will work. And there is a possibility that hearing loss could be permanent.
What’s important to remember is that you should see a health care provider in the event of hearing loss so you’re treated in a timely and appropriate manner.