What is a Cochlear Implant?
Cochlear Implants are electronic medical devices that are implanted under the skin behind the ear. These implants provide a sensation of hearing to the severely hearing impaired person. Cochlear Implants have been around since the 1980’s, and have helped over 500,000 patients hear again.
Who would benefit from a Cochlear Implant?
Children or adults who have a severe to profound sensori-neural hearing loss do not get adequate benefit from even the most powerful hearing aids. Such patients require Cochlear Implant Surgery in which a small implant is placed under the skin behind the ear. With the help of the implant, they can hear all sounds.
Can very young children with hearing loss be implanted?
Infants born with a hearing loss have a delay in their hearing, speech and language development. The severity of delay correlates with the severity of hearing loss. Babies with mild loss will develop a mild delay, but those with a severe to profound loss will usually develop very poor listening, speech and language skills, even if they wear powerful hearing aids. Such children would require a cochlear implant surgery, which can be done between 6-12 months of age at the earliest. After Cochlear Implantation, they learn to hear and speak, just like normal hearing children. Such children have grown up to finish school and university, and live near normal lives.
What is the ideal age for Cochlear Implants in Children?
Establishment and development of the centres and neural pathways in the brain for hearing, speech and language takes place after birth as the child listens to all the sounds in his/her environment. If a child does not hear sound, this development does not take place. It is also important to understand that this ability or ‘plasticity’ of the brain to learn to ‘hear’ is lost by the time the child is between 5-7 years of age. For this reason, it is of utmost importance to have an early diagnosis of hearing loss and to start appropriate intervention as early as possible.
Children over 4 years old who are diagnosed and fitted with hearing aids or Cochlear Implants tend not to do as well as those diagnosed early and fitted earlier in life. The ideal time for hearing aid fitting is as early as 3 months of age. And for Cochlear Implant surgery is 6-12 months of age.
Children implanted before the age of 12 months tend to develop almost like other hearing children. Most develop excellent hearing and speech.
What tests are required before surgery?
Hearing tests and Imaging tests are necessary prior to considering implantation. Hearing tests confirm the type, site and severity of hearing loss. Children with a loss of less than 70 dB are usually fitted with hearing aids, while more than 70 dB are planned for Cochlear Implantation.
Unaided audiometry, Aided audiometry, BERA, ASSR, Impedance audiometry and OAE screening are some of the hearing tests required. Imaging tests are a High Resolution CT scan of the bone of the ear and an MRI of the Inner Ear. These tests show the structural anatomy of the Inner Ear, the Auditory nerve and the Brain.
Presence of abnormal Inner Ear anatomy can change the choice of implant and electrode, as well as the prognosis. Presence of a thin hearing nerve can influence the side to be implanted. This is a decision taken in consultation with the audiologists and radiologists.
The Cochlear Implant Team
Dr Sharma’s experienced Cochlear Implant Team consists of surgeons, pediatric anesthetists, radiologists, audiologists and speech therapists. This team comprehensively evaluates any patient before the procedure is planned. Some children require evaluation by a Developmental Specialist, Child Psychologist, Paediatric Neurologist, Paediatric Ophthalmologist, Occupational Therapist, Paediatric Cardiologist, Genetic Specialist etc. The Cochlear Implant Team takes care of all the queries that the patient or parents may have at any point of the treatment. This also forms the core support group.
The process of Cochlear Implantation
After the decision to implant is taken, certain routine blood and urine tests are necessary prior to surgery. Admission is usually on the day of the surgery and discharge after 1-2 days.
During surgery, after the implant has been inserted, the computer aided telemetry is carried out by the audiologist to confirm that the device is fine and to record the responses from the brain. This recording during surgery helps in setting the parameters (MAP) of the processor at the time of ‘Switch-On’ of the implant.
A head bandage and a single suture (stitch) are present and these are removed 7-8 days after the surgery when the patient is called for a review.
‘Switch On’ of the Implant is when the child or adult wears the processor behind the ear and starts hearing sound for the first time after surgery. This is usually on the 8th-10th day after surgery. This is the happiest day for the parents and the doctors as the child is welcomed into the hearing world. The journey of hearing and speech development starts here.
What happens after Cochlear Implantation and Switch-on?
The Cochlear Implanted children and adults require periodic ‘mapping’ of the device by the Audiologist. The minimum (threshold) current level at which the sound is ‘just’ heard and the maximum current level at which the sound becomes uncomfortable is determined for each of the electrodes and then the processor is programmed accordingly.
In the first few months after surgery, frequent ‘mapping’ sessions are required, as the current levels required for stimulation will change with time as healing takes place. Later on, ‘mapping’ sessions will be required once in 6 months or longer, for which visits to the audiology clinic may be required. Nowadays, these mapping sessions can take place remotely via skype or zoom with the help of software which allows the audiologist to observe the child’s responses and change the device settings from the clinic while the patient is at their home.
AVT or Auditory Verbal Therapy Sessions are necessary in children to help them get the maximum benefit from the implant. AVT helps the child to learn to listen to sound, understand sound and subsequently go on to develop speech and language. Frequent AVT sessions with the AVT therapist is a must. For patients who live far away from the centre, sessions by skype are also possible.
Why choose Dr Shalabh Sharma and his team?
The Cochlear Implant Program at Sir Ganga Ram Hospital was established in 2001 by Dr Shalabh Sharma who is the Unit Head and Chief Cochlear Implant Surgeon at the hospital. He has completed over 1000 successful implants. His youngest patient at the time of implantation was 8 months old, and the oldest was 86 years old. In India, Dr Sharma has one of the best centres for Cochlear Implants providing all possible support for counselling, surgery and rehabilitation of a patient. He is a mentor to many surgical centres across India and lectures extensively on this subject both nationally and internationally.
What have we achieved so far as a team?
The first child to be implanted at the hospital in 2002 at the age of 2 years, is now studying in an engineering college. This is a source of immense pride for the entire team. Most of the implanted children who were implanted at an early age are in mainstream schools and colleges and doing very well. Some have gone to excel in studies and some are doing extremely well in sports, music and creative fields. Some kids have represented our country at various national platforms in various fields which leads us to believe that this is nothing less than a miracle. A Cochlear Implant does not only transform a patient’s life, it completes and fulfils the life of all the care givers in the team.
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