The Medical Consumer's Advocate

Sudden sensorineural hearing loss

 

Q: One morning about a year ago, my wife woke up and realized she couldn't hear in her left ear. We checked with the local experts, who prescribed antibiotics and anti-allergy medicines. An audiogram showed nearly 100 percent hearing loss in that ear. An ENT specialist suggested an MRI, which was negative. No one can determine the reason for the sudden hearing loss. Although my wife is getting used to the persistent whooshing noise in herleft ear, we are both really perplexed. Do you have any suggestions?

A: The condition you describe is known in the biz as "sudden sensorineural hearing loss," which for convenience I will abbreviate as SSHL. I suspect "sensorineural" may require some explanation, but "sudden hearing loss" is self-explanatory. Sensorineural hearing loss, more commonly called "nerve deafness," refers to hearing loss caused by damage to the cochlea (inner ear) or auditory nerve. The other common class of deafness is conductive hearing loss, in which sound is impeded in its ability to stimulate the inner ear. Ear wax, a perforated ear drum, fluid in the middle ear, and damaged middle ear bones are examples of problems which lead to conductive hearing loss. In general, conductive hearing loss is correctable, while sensorineural hearing loss is often irreversible.

Your wife’s story is, unfortunately, very typical for SSHL. Affected individuals often wake up with a hearing loss in one ear; others notice rapid loss of hearing in one ear over the course of minutes to hours. Tinnitus (your wife’s "whooshing noise") is common, as is a sense of fullness in the ear, and many individuals also experience dizziness of one form or another.

The good news is that bilateral problems are very rare; thus, your wife should not worry too much about losing her hearing in a similar way in her other ear. Another bit of good news is that SSHL is only rarely a sign of more serious disease. One common fear is brain tumor– specifically, a tumor on the auditory nerve (acoustic neuroma), although other brain tumors may also lead to SSHL. Your wife’s risk of having such a tumor was roughly 1% to 3%. This is why her ENT ordered an MRI scan. 1% to 3% may not sound too probable, but if an MRI were not obtained, there would be no other way of eliminating the possibility that she had such a tumor... and these tumors do grow! Most ENTs would agree that an MRI is necessary, for this very reason.

So, if tumor is rarely the cause of SSHL, what does cause it? Some infections have a well-known association with SSHL: syphilis, meningitis, reactivated chicken pox infection (herpes zoster oticus), congenital cytomegalovirus infection, measles and rubella. Head trauma can certainly lead to SSHL and/or sudden conductive hearing loss. Some antibiotics, chemotherapeutic agents and other drugs can cause SSHL. Sarcoidosis and multiple sclerosis are occasionally associated with SSHL.

Unfortunately, most cases of SSHL remain unexplained. Possible explanations of such unexplained cases include: unidentified viral infection, immunologic diseases (such as systemic lupus erythematosus), and vascular occlusion (essentially, an inner ear "stroke").

If an infectious etiology is strongly suspected, the doctor will treat it accordingly. Unfortunately, for many viral infections, no drug treatments are available. For SSHL of unknown etiology, the only drug treatment that is supported by solid medical evidence (randomized, double-blind, placebo-controlled studies) is corticosteroid therapy. This should be started as early as possible after the onset of the hearing loss. For a more thorough discussion of drug treatment for SSHL, you may wish to read Dr. Robert Dobie’s monograph on this topic (http://www.uthscsa.edu/oto/monogrf.htm).

What can your wife expect for the future? Those folks who recover from SSHL tend to have incomplete hearing loss at the outset; you noted that your wife’s loss was profound. Recovery, if it occurs at all, tends to occur within the first few weeks. Thus, the fact that your wife has a total hearing loss which has lasted a year suggests that her loss is most likely permanent.

What should she do now? She needs to conserve hearing in her only hearing ear. Some interventions are obvious (for example, avoiding heavy metal concerts and other noisy environments; wearing noise protection when noise is unavoidable.) Other things may be somewhat less obvious. For example, as noted above, certain medications may lead to hearing loss. Such medications should be avoided, unless they are necessary to save life or limb. She may also want to avoid (or at least show great caution) with certain activities which are known to pose a risk to the ears, such as skydiving or deep sea diving. She should also show great caution when cleaning her ears (swabs can cause serious injuries!) She should ask her audiologist and ENT for more advice on how to conserve hearing in her only hearing ear.

 

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