A cochlear implant is an electronic device that restores partial hearing to the deaf. In cochlear implant surgery, the implant is surgically placed in the inner ear and activated by a device worn outside the ear. Unlike a hearing aid, it does not make sound louder or clearer. Instead, the device bypasses damaged parts of the auditory system and directly stimulates the nerve of hearing, allowing individuals who are profoundly hearing-impaired to receive sound.
Cochlear implants use a sound processor that fits behind the ear. The processor captures sound signals and sends them to a receiver implanted under the skin behind the ear. The receiver sends the signals to electrodes implanted in the snail-shaped inner ear (cochlea). The signals stimulate the auditory nerve, which then directs them to the brain. The brain interprets those signals as sounds, though these sounds won’t be just like normal hearing.
The cochlear implant surgery is comprised of 2 parts :
The receiver which is an internal portion includes receiver or Stimulator and tiny electrodes. This devise is surgically implanted in the patient’s skull bone and this is placed behind the ear and the cochlea is implanted with the tiny electrodes.
The speech processor which is an outer portion or the external device has a transmitter along with Microphone. The speech processor comes in a variety of sizes with the wearing options.
The hearing loss is mainly of two types:
1. Conductive hearing loss as the name suggests occurs if there is a problem in sound waves conduction enrouting through the outer ear, tympanic membrane (eardrum), or middle ear. It may also happen if there is something that blocks the sound waves from reaching into the inner ear. The causes for such obstruction can be infections, holes in the eardrum, fluid or wax build-up behind the eardrum, or malfunction which is caused due to an infection in the part of the ear or a sudden or extreme change in air pressure and head injury. All these causative factors can lead to partial or conductive hearing loss. In such cases the treatment of choice is often surgical or medical intervention or sometimes this can even be corrected by hearing aids.
2. Sensorineural hearing loss occurs if there is damage to the inner ear or the nerve from the ear to the brain which passes the messages from inner brain to brain. This type of case has more likely to have permanent hearing loss and more common than the conductive hearing loss. The main contributing factors for Sensorineural hearing loss includes prolonged exposure to loud noise or due to ageing. In children the hearing loss is due to the congenital abnormalities or infections. Furthermore, injuries to skull or skull fracture, brain injury and Genetic disorders can also lead to sensorineural hearing loss.
The line of treatment is decided based on the type of hearing loss. Following details would give a brief idea about the treatment options available for hearing loss in India.
Treatment for Conductive hearing loss: The treatment suggested for conductive hearing loss is –
- Medical Management The drug or form of medicine which can be used to cure the infection or the diagnosis.
- Surgical Intervention which includes Canalplasty, Stapedectomy, Tympanoplasty and with or without ossicular reconstruction (Depending upon the diagnosis).
- Bone Anchored Hearing Aid (BAHA) is suggested if patient is profound to nearly normal hearing on one side or complete hearing loss in one ear. This procedure fitting consists of six stages like Investigations, treatment planning, selection, verification, orientation, and validation. The implant which is used in this procedure is Titanium Implant this is placed in the bone behind the ear. Later after a couple of months an external device is hooked up to the Titanium Implant which is similar to a hearing aid.
Treatment for Sensorineural hearing loss : The only promising treatment available for this type is Cochlear Implant. When hearing is so poor that hearing aids provide minimal or no benefit, a cochlear implant may be considered. Over 80,000 people worldwide benefited with cochlear implant surgery and half of all cochlear implant recipients are children’s. This device functions to stimulate the auditory nerve by passing through the injured inner ear. Patients with severe Sensorineural hearing loss still have a functional auditory nerve and the sensation of the sound is re- created by the implant.
A wide range of sound information and performance is expected from this device. With the best appropriate rehabilitation and the duration of time, patient experience clear understanding and more speech compared to the use of hearing aids.
The treatment goes in stepwise manner.
• Investigations/Evaluation : Patient undergoes relevant investigations which includes MRI, CT scan, X ray studies and a thorough evaluation by the team of audiologist.
• Consultation and Physical Assessment : Once the patient is identified for cochlear implant the procedure begins. The patient has a consultation with the ENT surgeons for confirming his or her candidacy based on the results of initial evaluation and investigation.
• Pre-anaesthesia evaluation and Surgery : The trial of anaesthesia is done. Its procedure is performed under general anaesthesia through an incision behind the ear. However, the whole procedure takes nearly 2-3 hours for the completion. Post discharge the recovery is in few days and follow ups and recuperation will be advised. After surgery you may see a swelling behind the ear which is normal and it may take some time to subside.
• Speech processor : This is hooked up to the stimulator or the receiver after four weeks of surgery.
• Rehabilitation : The patient is then advised to undergo intensive rehabilitation under implant audiologist to cope up with the listening of sounds through the device.
Post-Cochlear implant surgery the patient have to stay in hospital for around 1-2 days, the patients shall have stitches and the prevention caring instructions for the stitches will be advised and after a week the stitches are removed and the implant site is examined.
The external device is given after a month of surgery in the first programming session. The implant is activated after 3-6 weeks of surgery. If the patient had used hearing aids then the developed auditory skills is benefited in rehabilitation. The maximum benefit of the surgery is expected from rehabilitation which starts with speech processor, transmitter and battery pack fitting. To understand how to learn the sound and how to response to the sound the patient is thought well rehabilitation speech.
The approximate cost for unilateral cochlear implant surgery would range between USD 12000 to USD 18000 with basic implant. The cost estimate would vary depending upon the quality, version and brand of the implant, expertise of the surgeon and the facility where you choose to get the procedure done.