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Tinnitus or ringing in the ears 

Ringing in ears may be rooted in the brain, study shows

By Julia McNamee Neenan
HealthScout Reporter

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 it.

The study appears in the current issue of Neurology.

"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," Seidman says.

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 been unknown.

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 side.

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 longer worked.

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 says.

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 says.

"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 loss."

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 the ears.

For the most recent studies on tinnitus, including one that suggests the popular herb gingko biloba is not a helpful cure, try HealthScout.