Page last updated at 23:02 GMT, Saturday, 3 October 2009 00:02 UK

Technique can pinpoint tinnitus

nerve cell
MEG measures small electrical currents in nerve cells in the brain

It is possible to pinpoint the area of the brain that is activated when a person suffers from tinnitus, according to US doctors.

Tinnitus is a condition where sounds are heard in one or both ears when there is no external source.

While doctors had thought tinnitus was generated by ear problems, they now believe it is generated in the brain.

The team at Henry Ford Hospital in Detroit used a special scanner to map the locations in the brain.

They hope it will allow more targeted therapies to be developed.

The scan is called magnetoencephalography (MEG) and it measures the very small magnetic fields generated by intracellular electrical currents in the neuron cells in the brain.

The team at the Henry Ford Hospital have already tried using chips which generate electrical noise directly in the brain in two patients to try to interfere with the tinnitus signals.

They are presenting their findings to the annual meeting of the American Academy of Otolaryngology.

Scanning results

The doctors collected MEG results from 17 patients with tinnitus and 10 patients without.

They played patients various sounds until they agreed that that was the sound they experienced and then scanned their brains while the sound was played.

2.3 million sufferers in the UK with moderate or severe tinnitus
Characterised by a singing, ringing, buzzing or whistling noise in the ear
Some sufferers notice the sounds when it is very quiet, some find they are much louder
Tinnitus noise can beat in time with your pulse
Most people experience brief periods of tinnitus after long exposure to loud noise

For the patients with tinnitus in one ear, MEG imaging detected the greatest amount of activity in the auditory cortex on the opposite side of the brain.

For patients with ringing in both ears, MEG revealed activity in both hemispheres of the brain, with greater activity appearing in the opposite side of the brain to the ear with the strongest perception of tinnitus.

Dr Michael Seidman, director of neurologic surgery at the Henry Ford Hospital, who led the work, said 2-4% of sufferers had really persistent tinnitus that they found impossible to ignore.

He said: "Using MEG, we can actually see the areas in the brain that are generating the patient's tinnitus which allows us to target and treat it.

"Another part of the brain that lights up is the limbic system which is supposed to govern how we react to things.

"This may explain why some patients can fairly successfully ignore their tinnitus while others find themselves fixated on it."

Dr Seidman said imaging systems currently used to study tinnitus provide a general location compared to the sophistication of MEG.

He said: "It's like having the lights on in only the city of Detroit, compared to having the lights on in the entire state of Michigan."

Dr Mark Downs, executive director at the Royal National Institute for Deaf People said, more than half a million people in the UK had their health seriously affected by tinnitus.

He said: "This work could potentially solve a further piece of the tinnitus puzzle.

"It is a unique way to monitor how the brain is affected by tinnitus in real time, helping researchers to see how effective new treatments are."

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