Sudden Sensorineural Hearing Loss
The
following question and answer was circulated by Bob Elkins of the
SayWhatClub. Our thanks to him and to Dr.
Douglas Hoffman for the following information.
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 her left 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. 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. For a more thorough discussion of drug treatment for SSHL,
you may wish to read Dr. Robert Dobie's monograph on this topic.
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.
