Mice Help Scientists Find Cause of Tinnitus

Mice help scientists find cause of tinnitus

American researchers claim that they have pin-pointed the cause of tinnitus – a breakthrough they believe could be a major step in understanding how to treat this life-changing condition.

Tinnitus is thought to afflict ten per cent of the British population. Symptoms commonly involve hearing ringing, and buzzing noises loud enough to impair hearing and seriously reducing the quality of life.

At-risk occupations

Workers who work with loud machinery, professional musicians and armed service personnel are all vulnerable to having their hearing affected by their occupation.

No Win, No Fee solicitors such as Claims Direct can help people who need to make personal injury claims for hearing loss relating to accidents sustained in the workplace.

Over in America, the American Tinnitus Association reports that tinnitus is the most common service-connected disability among veterans of the Iraq and Afghanistan conflicts.

According to researchers at the University of Pittsburgh, it is only known that auditory circuits in the brain of tinnitus sufferers are more “excitable” than the circuits found in the brains of non-tinnitus sufferers. 

But scientists have been unable to ascertain whether this is due to the hyperactivity of tinnitus sufferers’ auditory circuits or the reduced activity of their inhibitory circuits’ reflexes. This mystery has baffled scientists – that is, the Pittsburgh team say, until now…

Laboratory mice

The latest research concentrated on laboratory mice, half of whom were sedated and exposed to noise as loud as an ambulance siren for 45 minutes so that they would exhibit tinnitus.

‘Startle’ experiments

Confirmation of the tinnitus was confirmed by ‘startle’ experiments, where a continuously loud tone (60 per cent as loud as the siren) was played for a period then briefly stopped. Finally, an even louder tone was played at the end of the experiment.

The report, published in the online edition of the Proceedings of the National Academy of Science, revealed: “Mice with normal hearing could perceive the gap between the noises and, because they were aware something had changed, were less startled than mice with tinnitus, whose ear ringing masked the moment of silence in between the background tones.”


Further examination of the rodents’ brain patterns found that their tinnitus was caused by under-inhibition of key pathways in the brain rather than hyperactivity or over-sensitivity in other pathways.

Research leader Dr Thanos Tzounopoulos concluded that agents which increase inhibition “might be effective treatment for tinnitus” and his team is now trying to identify such drugs.

The breakthrough could mean welcome news for employees who, through no fault of their own, have had their hearing damaged during their working lives.

In January 2011, it was reported that compensation payment cheques would be made to over 60 people who used to work at former truck works Fodens in Sandbach, South Cheshire.

Stephen Bailey of Middlewich was an employee at Fodens for 33 years and said that although some of the productions shops were very noisy “most of the time there was no form of hearing protection available”.

Mr Bailey added: “I now have a constant noise in my ears which sounds like a car engine ticking over. It is worse at night when everything else is quiet.”

It is highly likely that more workers who have damaged their hearing in the line of their work would claim compensation if they knew they were eligible.