or ringing in the ears
Ringing in ears may be rooted in the
brain, study shows
By Julia McNamee Neenan
WEDNESDAY, Feb. 28 (HealthScout) -- Changes in the brain's
ability to prioritize perceptions may cause some forms of
ringing in the ears, new research shows.
Looking at patients whose tinnitus, or
ringing in the ear, worsened when they looked sideways,
doctors found an imbalance between the auditory and visual
parts of the brain. Normally, the brain can pick which sense
is more important at that moment.
The study suggests a new avenue for
research into tinnitus, says lead author R.F. Burkard.
Doctors have long thought tinnitus may be "some kind of ear
itch," Burkard says. Instead, the noise may be present for
many of us, but our brains block it out so we never perceive
The study appears in the current issue of
"Do we think we have a cure for this on
the horizon? Uh-uh. But it tells us something interesting,"
Burkard says. "Maybe normally when we move our eyes, we
suppress information coming from the auditory domain [in
the brain], and maybe that's been impaired."
This particular form of tinnitus accounts
for only a very small percentage of those with tinnitus, so
the study's immediate application is limited, says Dr.
Michael Seidman, director of otolaryngology at Henry Ford
Health System in Detroit. But the researchers involved with
the study are respected, and it may turn out to suggest
research for other forms of tinnitus as well.
"Perhaps some of the long-term insight or
information we gain from this will help more people,"
Tinnitus affects up to 50 million
Americans, 2 million of them so seriously they can't work or
sleep. Researchers believe it exists in a number of forms,
which may be rooted in different causes. But the causes have
Burkard and his colleagues looked at
eight patients who had had surgery to remove a tumor from
the auditory nerve; in the process, all eight lost hearing
in the involved ear. All began to suffer from tinnitus -- in
their deaf ears -- and they discovered the ringing became
louder and sometimes higher when they looked to the
The researchers used positron emission
topography (PET) scans to examine the patients' brain
activity. In a PET scan, radioactive water is injected into
a patient's brain; the areas that are most active will
absorb the oxygen from the water most rapidly and light up
during the scan.
First, the researchers compared the eight
patients with themselves: they served as their own control
group. PET scans showed that when the patients looked
sideways and experienced more ringing, the auditory cortex
of their brains lit up; this did not happen when the
patients looked straight ahead.
As with sensations in a phantom limb,
what was significant was that the patients were deaf,
Burkard says: "This flavor of tinnitus is not coming from
the ear, because nothing is coming from the ear."
The noise had to be a perception of a
noise, and it had to come from the brain since the ear no
Second, the researchers compared the
eight with an outside control group. This time, they played
a tone in the subjects' hearing ear and looked at brain
activity. Everyone reported hearing the tone, but again, the
group with just one working ear showed much more activity in
the auditory cortex of the brain.
"We believe when you get any hearing
loss, one of the things that happens is that the brain
changes its response to maximize what's left," Burkard
All kinds of noises are present in our
environments, and we attend to what we want to hear. Perhaps
this ability is impaired in people with tinnitus, Burkard
"How your brain pays attention to
something is it turns unimportant things off," Burkard says.
"Your ability to selectively turn off unimportant
information may be impaired when you get a hearing
Other researchers are looking at patients
whose tinnitus is worsened when they touch a section of an
arm or leg, Burkard says.
Seidman says another scientist is working
with patients who can control the severity of their tinnitus
by opening and shutting their mouths. Increasingly, they
say, it is looking as if tinnitus has to do with the brain
and perceptions of sounds.
For treatment, this means doctors will be
focusing not on the ear, but on the central nervous system,
Burkard says; perhaps by reversing the brain's
overcompensation for hearing loss and gaining back the
ability to block out the ringing noise.
What To Do
For more on tinnitus, you can try the
American Tinnitus Association. And the American Academy of
Otolaryngology also has valuable information on ringing in
For the most recent studies on tinnitus,
including one that suggests the popular herb gingko biloba
is not a helpful cure, try HealthScout.