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April 28, 2007

New technology to the rescue of deaf children

From: Hindu - Chennai,India - Apr 28, 2007

New Delhi, April 28. (PTI): For parents whose children are born stone-deaf, there is a silver lining -- thanks to a technology that provides them not only sound and speech perception, but gives them a chance to lead a normal and healthy life.

Doctors at AIIMS have given a gift of a better life to 118 children by implanting Cochlear implants in them since the launch of the programme nine years ago.

The institute, which is the first Government Hospital to start this expensive procedure in the country, was also the first to implant it in a child as young as fifteen months, said R C Deka, Head of the ENT Department at AIIMS.

The implant, which costs over Rs 5 lakh at the institute, is an electronic device which restores partial hearing to the deaf and is surgically implemented in the inner ear and activated by a device worn outside the ear, he said.

The implant, which is unlike a hearing aid, does not make sound clearer but bypasses the damaged parts of the auditory system and stimulates the nerve of hearing, making individuals who are profoundly hearing impaired perceive sound.

"As those who have come to us belong to poor families, they benefited through philanthropic gestures of various agencies like the Army, Railway or an NGO," he told PTI.

So far 158 persons have benefited, of which 118 have been children. "We are the only Government institute where people have benefited with this costly technique that gives life support to those who don't even sense sound," Deka said.

"There is a proposal with the Government in the advance stage of consideration where children will be provided Cochlear implant at an affordable cost," he said.

Children are born deaf due to various reasons, including genetic deafness, infection, or early child disease like meningitis.

"Adults need the surgery if they had a accident in which their hearing nerve have been affected," Deka said.

The implant bypass damaged hair cells and convert speech and environmental sounds into electrical signals and send these signals to the hearing nerve.

The surgeon said, after the surgery in which the implant is surgically implanted under the skin behind the ear training is given to the patient about how to use it.

Apart from an external speech processor that is usually worn on a belt or in a pocket, a microphone is also worn outside the body as a headpiece behind the ear to capture incoming sound.

The speech processor translates the sound into distinctive electrical signals and these 'codes' travel up a thin cable to the headpiece and are transmitted across the skin via radio waves to the implanted electrodes in the cochleas, he said.

"The electrodes' signals stimulate the auditory nerve fibres to send information to the brain where it is interpreted as sounds," he said.

The doctor said, if a child between the age of one to five years is fitted with the implant then it is easy for him to learn quickly.

"He grows up sensing sound and speaking. Many of the children who we have operated at at an early age have taken admission in normal schools," he said.

But if the parents bring the child at a later stage, he would find it difficult to sense sound and speech. "He would take a long time to learn the speech and sound," Deka said.

Before a person is fitted with the implant, doctors carry out physical examination, including X-ray, MRI scan to evaluate the inner ear bone and psychological test.

Doctors don't fit the implant in a person who has any disability. "The child or the adult should not have any disability apart from the hearing one. The implant won't help them," Deka said.

He said, during the surgery also they could make out whether the person would benefit with the implant or not. "After four weeks of the surgery, we start training the child and then their parents," he said.

During the training of a child with the speech therapist, the child is taught how to differentiate sound. Later, they are taught about vowels and short phrases.

"The training is slow but we build it up by matching the sounds with visuals so that the child could pick the skill fast," he said.

"The regular training has helped. Eighty per cent of our children whom we have fitted with cochlear implant have joined normal schools," he said.

© 2007, The Hindu.