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As printed in Hearing Health, volume 20:4,
Winter 2004
by Steven D. Rauch, M.D.
Sudden deafness, more correctly known as sudden sensorineural
hearing loss (SSNHL), is a common hearing emergency.
In the U. S. alone, there are up to 52,000 new cases
of SSNHL each year. About one-third of the affected
individuals will recover their hearing, one-third will
improve slightly and one-third will remain deaf in the
stricken ear. Fortunately, SSNHL almost always affects
only one ear and rarely spreads to the other side. Even
so, single-sided deafness seriously impacts one’s
ability to hear, especially in noisy environments, and
makes it nearly impossible to locate the direction from
which sounds are coming.
SSNHL is defined as new onset, unexplained hearing
loss in one ear that develops over a 72-hour period
or less. In some cases a person feels a “pop”
or senses the sudden onset of tinnitus (ringing in the
ears) and hearing drops sharply over a few minutes or
a few hours. In other cases a person may wake in the
morning with hearing loss. Some people report hearing
fluctuations for days before the final loss occurs.
There is almost always some feeling of a plugged ear
or ringing in the ear and varying degrees
of imbalance or even vertigo that accompanies the SSNHL.
Because ear fullness
(the plugged sensation) is so common, people often delay
for days or weeks before seeking medical attention.
Unfortunately, with SSNHL, there is a narrow window
of opportunity for treatment and delay may result in
a permanent loss of hearing. An
ear examination and a hearing test can confirm the nature
and the degree of sudden hearing loss.
Although only first formally described in 1944, SSNHL
has been around a long time and in spite of much research,
the cause and ideal therapy have not been determined.
Many treatable conditions such as acoustic neuroma,
Meniere’s disease and acoustic trauma often cause
SSNHL and these must be considered and excluded. The
majority of cases have no obvious cause, although SSNHL
symptoms have been linked to many systemic problems
such as bacterial and viral infections, metabolic disorders,
inflammations, stress, hypertension and immunologic
and allergic disorders, among others.
SSNHL may be due to a virus infection. If the virus
attacks the nerve to the inner ear, recovering hearing
is likely. Conversely, a virus that directly attacks
the sensory cells of the inner ear may cause severe
hearing loss and recovery is poor. Both occurrences,
however, can have the same clinical signs and symptoms.
If left untreated, a minority of cases will show spontaneous
hearing improvement in the two-to-four weeks after onset
but hearing rarely improves thereafter.
Studies have shown that early administration of a high
dose of an oral steroid, prednisone, may increase the
rate of hearing recovery from about 30 percent in people
left untreated to about 60 percent in treated cases.
A significant amount of irreversible inner ear damage
prior to taking the steroid or an insufficient amount
of the steroid reaching the inner ear target may explain
why this therapy only benefits slightly more than half
of patients treated.
In the last few years, a number of uncontrolled case
studies have suggested that SSNHL can also be effectively
treated by steroid injections directly into the ear
(intratympanic or IT therapy). Some of these reports
documented IT steroid success even in cases that had
failed to respond to oral steroids or in cases when
treatment was started up to six weeks after the onset
of deafness. These observations indicate that the current
standard treatment of a short course of oral steroids
is often inadequate for maximum hearing recovery and
that local steroid delivery may have a role in treating
SSNHL. Although we cannot determine from these uncontrolled
case series whether IT steroids are more effective than
oral steroids, this treatment is rapidly being adopted
by clinicians who are seeking some means of obtaining
further hearing improvement in SSNHL.
To answer the question of whether oral or IT steroids
is the best treatment for SSNHL and define the risks
and benefits of these two treatments, the National Institutes
of Health-Institute of Deafness and Other Communication
Disorders (NIH-NIDCD) is sponsoring a national multicenter
clinical trial comparing these two treatments.
The SSNHL multicenter treatment trial includes investigators
from eight medical centers (Harvard University, University
of Massachusetts, New York University, Johns Hopkins
University, Cleveland Clinic, University of Michigan,
University of Iowa, and University of California at
San Diego) plus a data management center (Hines Veterans
Administration Hospital), chaired by me, Steven Rauch,
M.D.
We began enrolling individuals for the study in the
fall of 2004. Qualifying patients who agree to participate
are randomly assigned to receive either oral or IT steroid
treatment. Their pre-treatment and post-treatment hearing
is measured and monitored for six months. Once enough
people have been treated, the data will be analyzed
to evaluate the pros and cons of the two treatments.
A total of 254 people with SSNHL (127 in each treatment
group) are needed to complete the study. They must be
seen at one of the study centers within 14 days of the
onset of SSNHL, ideally much sooner. Anyone who experiences
a sudden loss of hearing in one ear should contact the
nearest study center if they would like to be included
in the study.
Anyone experiencing the symptoms of sudden deafness,
even those not interested in participating in the study,
should seek immediate examination by an audiologist
or ear, nose and throat doctor. Missing the window of
opportunity for steroid therapy can be very frustrating
for both patient and ear physician. One potential benefit
of this study in progress will be to highlight and publicize
this disorder and its treatment. The study has been
designed to conform to the rigorous standards required
for publication in a leading medical journal in order
to raise awareness of SSNHL among the general medical
and emergency medical communities and eventually the
public with the hope that education will lead to earlier
intervention and higher rates of treatment success.
While SSNHL is not one of the most common causes of
deafness, the fact that it is potentially reversible
makes it a very important topic for study. The results
will shed light on some of the basic biology of the
inner ear in health and disease and also will provide
the scientific basis for practitioners to provide the
best evidence-based medicine in treating SSNHL, ultimately
improving the chances of recovering hearing when sudden
deafness strikes.
Steven D. Rauch, M.D., is associate
professor of Otology and Laryngology at Harvard ÞMedical
School and a member of the Otology Service of the Massachusetts
Eye and Ear Infirmary. He received his B.A. cum laude
from Amherst College and M.D. from University of Cincinnati.
He took his Otolaryngology training at Massachusetts
Eye and Ear Infirmary where he joined the faculty in
1984. Dr. Rauch divides his time between his clinical
practice of Otology and his research.
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