A Solution for Deafness

Cochlear implants can improve hearing in people with severe hearing loss who are no longer helped by using hearing aids. Cochlear implants can improve their communication and quality of life………
By Abhigyan/Abhinav

Hearing is a very important sense which helps us to communicate with each other. Lack of hearing makes the person mute also since the development of vocal skills is dependent on normal hearing.

According to Dr A K Agarwal, Former Dean and ENT Specialist, Maulana Azad Medical College, New Delhi and Presently Medical Advisor, Clinical Innovation, Apollo Hospital, New Delhi, the hearing loss can be present at birth which is called as congenital hearing loss or it can develop after birth when it is called acquired hearing loss. The hearing loss occurring after the speech and language development is termed as post lingual hearing loss. The child who is having hearing loss since birth and has not developed speech and language is termed as prelingual deafness.

“There are many causes of congenital deafness. These are hereditary causes which may sometimes be associated with syndromes like Down’s syndrome, Waardenburg Syndrome, Usher, Alport etc. Hearing loss can also occur due to maternal infections, complications during childbirth and pregnancy or because of certain drugs taken during pregnancy. It has been observed that mutation in gene leading to synthesis of a protein connexin 26 is responsible non-syndromic deafness. The incidence of congenital deafness in India is around 1-3 per thousand births,” Dr Agarwal, added.

Dr J C Passey, Former, Director Professor and Head, Department of ENT & Head Neck Surgery, Maulana Azad Medical College, said “It is essential to recognise any hearing loss in a child as early as possible since the speech, hearing and overall mental development depends on normal hearing abilities of the child. Parents have a very important role in early identification of such infants. Usually the child moves his head or blinks in response to loud sound. Also the child may startle or stop moving his limbs when there is a loud sound.”

“In case of suspicion the hearing status of the child must be objectively assessed at the earliest. The government of India is trying to make the universal screening of every new born child mandatory before discharge from the medical facility. In case of institutional deliveries, child’s hearing status is being routinely screened using otoacoustic emissions (OAE) which can be easily done with a portable hand held machine. Presence of OAE indicates normal hearing but absence of OAE does not mean that the child is deaf and it needs to be confirmed by a more specific objective test.” Dr J C Passey, added.

According to ENT Specialists, the brain’s ability to learn new things is slowly lost by the age of 5 years. When a child is rehabilitated for hearing after the age of five years, the normal speech may not develop as the brain has lost the ability to learn speech and language. That is why the deaf child must be diagnosed and rehabilitated at the earliest. Our aim should be to diagnose deafness and rehabilitate the child in the first year of life.

Rehabilitation depends on the degree of hearing loss. A child who is having mild to moderate hearing loss can be provided with a hearing aid. Hearing aid will amplify the sound above the hearing threshold of the child and he will be able to listen. Children with severe to profound deafness will require a cochlear implant though all such children must undergo a hearing aid trial before cochlear implantation.

Cochlear implant is a device which by-passes the inner ear and directly stimulates the cochlear nerve which is responsible for carrying the sound coded electrical signals to brain. The device has an internal part which is surgical implanted inside the ear and comprises of an electrode and a receiver magnet. The electrodes are inserted in the cochlea where they come in direct contact with the nerve endings of the cochlear nerve. The external part has receiver, speech processor and transmitter. The receiver has a microphone which picks up the sounds from external environment and sends it to the speech processor. The speech processor is like a computer which analyzes and digitizes the sound and sends them to a transmitter which stimulates the implanted receiver magnet just under the skin by electromagnetic induction.

Cochlear implants may be placed in one ear (unilateral) or both ears (bilateral). Adults will often have one cochlear implant and one hearing aid at first. Adults may then progress to two cochlear implants as the hearing loss advances in the hearing aid ear. Cochlear implants are often placed in both ears at the same time in children with bilateral severe hearing loss — particularly for infants and children who are learning to speak and process language. Adults of any age and children who are as young as 6 to 12 months old can benefit from cochlear implants.

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