Hearing Implant service at Apollo Hospitals.
The cochlear and hearing implant programme at Indraprastha Apollo Hospitals offers implantation for all types of cochlear and other ear/hearing implants (such as BAHA implant and Vibrant Soundbridge middle ear implant). Dr Ameet Kishore is the lead cochlear implant surgeon, and has personally carried out over 300 cochlear implants in the last four years alone. He along with Dr Pranav Kumar, Sr. Consultant Neurosurgeon, have also performed the first Auditory Brainstem Implant at Apollo Hospitals.

What is a cochlear implant ?
A cochlear implant is an electronic device that can restore useful hearing and provide improved communication abilities for persons who have severe to profound sensorineural hearing loss (nerve deafness) and who cannot benefit from hearing aids.

How is an implant different from a hearing aid?
Cochlear implants differ from hearing aids in two important ways:

1. Hearing aids simply amplify sounds.  A cochlear implant, on the other hand, transforms speech and other sounds into electrical energy that is used to stimulate the hearing nerve in the inner ear.

2. Unlike most hearing aids, cochlear implants have both internal and external components.  The implant system consists of an external speech processor and headset (worn behind the ear) and an internal, surgically implanted receiver/stimulator package with an electrode array.

How does the cochlear implant work?
For people who are cochlear implant candidates, the outer ear and the middle ear function normally.  However, in the inner ear (cochlea), the tiny hair cells are damaged or missing and do not generate electrical pulses to be sent to the hearing centres of the brain.  Therefore, the brain does not perceive the sound. 

The cochlear implant attempts to replace the function of the hair cells with electrical stimulation. Sounds are picked up by the microphone of the speech processor. The speech processor analyses and codes sounds into electrical pulses. These pulses are sent to the surgically implanted receiver/stimulator package and through to the electrode array, which stimulates the residual nerve fibres in the cochlea. The hearing nerve then sends these electrical pulses to the brain and which are finally interpreted as sound.

Who can benefit from Cochlear Implants ?
Any adult or child with bilateral (both ears) severe to profound sensorineural (nerve) hearing loss who obtains little or no benefit from hearing aids would be considered a candidate for a cochlear implant. Such deafness may be acquired following infection (such as meningitis), toxic effect of ototoxic drugs, trauma or age associated hearing loss.

Some children may be born with deafness. Such congenital hearing impairment is not uncommon with 2 to 3 out of every 1000 live births are born with significant hearing loss. Such children need to be identified at the earliest. This ensures that appropriate measures are undertaken to rehabilitate their hearing loss at a time when language skills can most easily be acquired. Many of these children may eventually require a cochlear implant.

Before the Cochlear Implant Surgery
There are various factors that need to be taken into consideration prior to cochlear implantation. Patients who may be candidates for cochlear implantation would have met with their audiologist and ENT(Hearing implant) Surgeon and the team would decide the best option for the candidate.

1. Complete audiological and speech therapist assessment and trial with hearing aids. We need to know the severity of the hearing loss, level of speech and language and the degree of benefit one gets with any current hearing aids. We may often ask for input from other professionals such as developmental paediatrics, neurology, psychology etc.

2. Imaging - CT and MRI scanning of the ears and brain. We need to see the structure of the ears and the condition of the inner ear and hearing nerves.

3. Routine preoperative blood tests for anaesthesia. Patients would also be seen by a physician or paediatrician (in the cases of children) to ensure they are fit for general anaesthesia. All candidates need to be vaccinated (against H.influenza, Pneumococcus and Meningococcus) to reduce the risk of infections.

Cochlear Implant Surgery
Hospital stay is likely to be a maximum of two days. We would normally admit on the day of the operation provided all the preoperative tests are satisfactory

Cochlear implant surgery lasts about two hours and is performed while the patient is under general anaesthesia.  The electrode array is inserted into the cochlea.  The receiver/stimulator is secured to the skull. Typically, patients remain in the hospital for two nights. They have a bandage on their head which is removed after four days. Patients return to school or work as soon as they feel well enough to do so, usually within a week of surgery.

Switching on the implant
Activation of the implant takes place three to four weeks after implantation, allowing enough time for the incision to heal properly. Following this the implant is ‘programmed’ or ‘mapped’. Mapping is done on a regular basis during postoperative rehabilitation to fine-tune the processor and get the best performance as the patient gets used to hearing with the implant.

Postoperative (Re)Habilitation
(Re)Habilitation is an essential part for those who have undergone Cochlear Implantation and may be carried out at the hospital or at a centre close to the patients home. All patients need Auditory Verbal Therapy (AVT). In Auditory Verbal Therapy, the emphasis is laid on making the child listen and speak normally, rather than on lip reading and visual cues. Learning to listen takes time and requires concerted efforts from the patient, the family and the person providing habilitation services. Thus the implant can offer a wide range of benefits, including hearing speech, environmental sounds and music.

What is an Auditory Brainstem Implant ?
An auditory brainstem implant (ABI) provides a sensation of hearing to deaf people by directly stimulating the cochlear nucleus in the brain. This implant uses similar technology as the cochlear implant, but instead of electrical stimulation being used to stimulate the cochlea, it is used to directly stimulate the cochlear nucleus in the brain stem of the recipient.

Because it bypasses the cochlear nerves, the device is most useful for people who have an absence or damage to the cochlea or cochlear nerves (which precludes the use of a cochlear implant).

How does an ABI work ?
The device comprises a processor positioned by the ear, a receiver/stimulator and an array of electrodes. The electrode array of the ABI connects directly to the brainstem, bypassing the damaged cochlea and cochlear nerves. The microphone in the processor picks up sounds from the environment and digitally transmits them to the receiver stimulator placed under the skin. The receiver/stimulator stimulates the brainstem electrodes, allowing the patient to hear a variety of sounds.

Who can benefit from an ABI ?
Any adult or child with bilateral (both ears) severe to profound sensorineural (nerve) hearing loss who might have been candidates for a cochlear implant but cannot receive a cochlear implant due to absence or damage to the cochlea or cochlear nerves would be a candidate for an ABI.

Such situations may occur due to trauma, illness(such as meningitis), tumours of the hearing nerve(acoustic neuromas) or may be a birth anomaly.

Before the ABI Surgery
All the factors that we consider prior to cochlear implantation are considered prior to an ABI as well. It is usually after the imaging that the problem with the cochlea or cochlear nerves is often detected, and the possibility of an ABI is then considered. In addition, the neurosurgeon also will assess the patient.

Auditory Brainstem Implant Surgery
This operation is done along with an experienced neurosurgeon. Hospital stay is likely to be a week.

ABI surgery may last for 6 to 8 hours and is performed while the patient is under general anaesthesia. The electrode array is inserted into the brainstem.  The receiver/stimulator is secured to the skull. Typically, patients remain in the ICU for a night before being shifted to their room. They have a bandage on their head which is removed after a week.

Switching on the AB implant
Activation of the implant takes place four to six weeks after implantation. Following this the implant is ‘programmed’ or ‘mapped’. Mapping is done on a regular basis during postoperative rehabilitation to fine-tune the processor and get the best performance as the patient gets used to hearing with the implant.

Postoperative (Re)Habilitation
(Re)Habilitation is an essential part for those who have undergone ABI and may be carried out at the hospital or at a centre close to the patients home. All patients need Auditory Verbal Therapy (AVT). The range of sound will not be to the level provided by cochlear implants, but it provides increased environmental sound awareness. Most patients are able to hear sounds and the degree of hearing usefulness can vary greatly. Some people get good word recognition, while others get more general sound cues. In combination with lipreading, the cues help improve communication with others. Our hope is that this can give patients a much improved quality of life.