Child Deafness Linked to ‘Lazy Ear’

Temporary deafness during childhood may lead to a form of "lazy ear" that affects long-term hearing, research suggested.

Scientists have likened the condition to amblyopia, or "lazy eye", which causes loss of vision because the brain fails to pick up seen images.

Lazy eye arises when balanced visual signals are not transmitted from each eye as neurons form connections during a critical period of brain development.

Dr Daniel Polley, who led the new research at the Massachusetts Eye and Ear Infirmary in Boston, the US, said: "An analogous problem may exist in the realm of hearing, in that children commonly experience a build-up of viscous fluid in the middle ear cavity, called otitis media with effusion, which can degrade the quality of acoustic signals reaching the brain and has been associated with long-lasting loss of auditory perceptual acuity."

In a laboratory study, Dr Polley's team reversibly blocked hearing in one ear of infant, juvenile and adult rats. The scientists then looked at how parts of the brain involved with hearing were affected.

Temporary hearing loss in one ear distorted sensory connections in the brain. As a result, the "deaf" ear's representation in the brain was weakened and the "open" ear's representation strengthened.

The re-organisation was most pronounced in the auditory cortex region, and most evident when hearing loss occurred in infancy.

Badly programmed connections in the developing auditory cortex may underlie "amblyaudio" in the same way that a wrongly wired visual cortex contributes to "amblyopia", said the researchers writing in the journal Neuron.

Dr Polley added: "The good news about amblyaudio is that it is unlikely to be a permanent problem for most people. Even if the acoustic signal isn't improved within the critical period, the mature auditory cortex still expresses a remarkable degree of plasticity.

"We know that properly designed visual training can improve visual acuity in adult amblyopia patients. We are gearing up now to study whether auditory perceptual training may also be a promising approach to accelerate recovery in individuals with unresolved auditory processing deficits stemming from childhood hearing loss than in later life."

 

Source: The Press Association - http://tinyurl.com/yjgebou

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This entry was posted in Child Brain Development, Child Health, Parenting & Education.

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