According to WHO, hearing loss affected nearly 63 million people in India in 2018.1 The occurrence of hearing loss rises with age; it is also associated with higher unemployment, depression, social isolation, and cognitive decline.
Hearing loss is usually treated with minor medical procedures or by using hearing aids. For individuals who are not benefitted with these conventional options, hearing implants are recommended.
Hearing implants are special devices that are surgically fitted inside or on the skull. There are various types of hearing implants, of different styles and shapes, where each one can be automated to manipulate sound to suit the specific requirements of the individual. Some types of implants include bone-anchored hearing aids, middle ear implants, cochlear implants, etc. Technological advances in these devices over the years have improved these three leading implants.
Individuals with the following indications are eligible for hearing implants:
- Sensory hearing disorders approaching the indication range of sound-enhancing hearing aids
- Functional disorders of the middle ear that cannot be treated by ear surgery
- Conductive hearing losses
- Ear malformations
- Presence of foreign bodies in the auditory canal, like ear moulds
- Conditions like eczema of the auditory canal or chronic otitis externa
PREPARATION BEFORE PROCEDURE
During the initial consultation, a complete medical examination is done to evaluate what procedure is best suited for the patient
The following tests may be performed to evaluate the patient’s condition:
- Examination of the external, middle, and inner ear for any signs of abnormality or infection
- Several tests of hearing, like audiogram
- Tests to assess the inner and middle ear structures
- CT scan and MRI scans to evaluate the shape of the cochlea and to check for any abnormal bone growth
- Psychological tests to check if the patient can cope with the implant
- Also, a trial of the hearing implant may be done to analyse its potential benefit.
Based on the procedure, your doctor will give certain instructions to be followed before the procedure.
The following are some of the types of implantable hearing devices and the procedure for their implantation.
Bone anchored hearing aids:
Bone-anchored device, also known as osseointegrated device, is a surgically implanted device that is suited for individuals with single-sided deafness or issues in their middle or outer ears. This device consists of external and internal elements.
A small titanium implant is placed into the skull bone behind the ear. A sound processor is attached to this implant by internal and external magnets or an abutment. This processor transfers sound vibrations to the inner ear by bone vibration, bypassing the outer and the middle ear.
A cochlear implant is a device that helps individuals who have severe, permanent hearing loss caused by the problems in the cochlea. Cochlea is a part of the ear that transforms sound vibrations into signals to be sent to the hearing nerve (auditory nerve), which in-turn sends signals to the brain.
A cochlear implant consists of 2 main parts:
An external microphone placed behind the ear that collects sound and converts into electrical signals, which are transferred along a wire to a device on the skin.
An internal device implanted in the skull that receives the electrical signals from the external device and transfers them to the cochlea through the wires.
Before a cochlear implant, an assessment is done to check if the auditory nerve is working properly.
Middle ear implants:
Middle ear implants are surgically implanted devices that are an option for individuals with outer ear infections, skin problems in their ears, earmould allergies, collapsed, narrow, or closed ear canals, or malformed ears. These devices send a signal to the middle ear, which mechanically vibrates the middle ear bones, thereby increasing the sound vibrations entering the cochlea. The cochlea converts these vibrations into electrical signals, which are sent to the brain.
Auditory brainstem implants:
An auditory brainstem implant is mostly used to treat patients who lost their hearing ability due to a trauma to the auditory nerve that is responsible for hearing, or due to severely abnormal cochlea or a missing or very small auditory nerve. Such patients cannot benefit from a cochlear implant or hearing aids.
The auditory brainstem implant stimulates the brainstem directly, without involving the inner ear and hearing nerve. An auditory brainstem implant has two parts:
An external part that comprises a microphone and speech processor (which is usually implanted behind the ear), a lead and a transmitter coil.
An internal part that is surgically implanted on the brainstem. This part includes a receiver and several electrodes that stimulate the brainstem.
The implant is switched on a few weeks after the implantation of the external parts, and the speech processor is tuned to meet the patient’s requirements over time. After implantation, professional support is essential to help the wearer to learn to listen and understand the signals from the implant.
The surgical procedure for hearing implants depends upon the type of implant being used.
After a hearing implant surgery, the incision site will mostly be wrapped in a bandage to protect it. Your doctor will give you instructions on how to care for the incision site and also prescribe some medications. Your doctor will inform you when to remove the bandage, which is usually a few days after implantation.
Once the bandage is removed, there may be some swelling around the incision site, which will disappear after the incision heals. There may be a slightly raised bump where the implant has been placed.
After a few weeks, you might have to visit the doctor to activate the processor. Certain implants require many sessions with an audiologist to regulate the sound processor and to learn to use and interpret the signals. This course may take many months.
Recovering from your hearing implant surgery is a long process, but not complicated.
Based on the type of device implanted, the recovery period may vary. However, here are some tips that may help you recover faster after implantation:
Ensure that you take your medications prescribed by the doctor and follow all the instructions give.
After the bandage is removed, clean the incision site every day with warm, soapy water, and pat dry.
You will be instructed when you can take a shower and wash your hair, which is usually a week after the surgery. But, take care that water does not enter your ear.
Eat healthy food and stay hydrated, as it can promote healing and help you deal with the side effects of anaesthesia (if any).
During the recovery period, the help and support of your family and friends are essential. Rest well in the recovery and look forward to what’s to come when you hear for the first time.
FACTORS AFFECTING COST
The following are the factors that affect the cost of hearing implants:
- Geographical location
- The type of implant
- The number of days in the hospital
- Cost of tests done before surgery
Bone-anchored hearing aids can help individuals with a narrow ear canal or chronic ear infections. However, your doctor will assess what implant will best suitable for you.
No, one cannot hear immediately after the surgery as he/she will not have the external components of the implant. The external components are given a month after the implant surgery.
Neurofibromatosis type 2 is a rare genetic condition which may cause tumors to grow on or near the auditory nerve. These tumors can be removed by surgery, but this surgery might have a major impact on one’s hearing. While removing the tumor, the surgeon may place an auditory brainstem implant to help with hearing.
Most insurance policies cover hearing implant surgery. However, contact your insurance agent to know the details of the policy for the type of hearing implant you will receive.