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 her left ear, we are both really perplexed. Do you have any suggestions?

Tom

The condition you describe is known in the biz as "sudden sensorineural hearing loss," which for convenience I will abbreviate as SSHL. 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 type of deafness is "conductive hearing loss," in which sound is unable to adequately stimulate the inner ear. Ear wax, a perforated ear drum, fluid in the middle ear and damaged middle ear bones are examples of problems that 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. Affected individuals often wake up with 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. Many individuals also experience dizziness.

The good news is that problems affecting both ears are very rare. 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 (called an acoustic neuroma), though other brain tumors may also lead to SSHL. Your wife's risk of having such a tumor was roughly 1-3 percent. That's why her ENT ordered an MRI scan, which is needed to rule out this possibility.

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 (CMV) infection, measles and rubella. Head trauma can certainly lead to SSHL as well as 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. Possibilities in these hard-to-categorize cases include: an unidentified viral infection, an immune-system disease such as systemic lupus erythematosus or a blocked blood vessel (essentially, a "stroke" in the inner ear).

If an infection is strongly suspected, the doctor will treat it accordingly. Unfortunately, for many viral infections, no medications are available. For SSHL of unknown etiology, the only drug treatment that is supported by solid medical evidence (in the form of randomized, double-blind, placebo-controlled studies) is corticosteroid therapy. This should be started as early as possible after the onset of the hearing loss.

What can your wife expect for the future? Recovery, if it happens at all, tends to occur within the first few weeks. Thus, the fact that your wife has a total hearing loss that has lasted a year suggests that it is most likely permanent. Now she needs to conserve hearing in her other ear. Some strategies are obvious (for example, avoiding noisy environments and wearing ear protection when noise is unavoidable). Medications known to lead to hearing loss should also be avoided, unless they are necessary to save life or limb. Your wife may also want to avoid activities 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!) Her audiologist and ENT can provide more advice on how to conserve hearing in her only hearing ear.