Cochlear implant

Cochlear implant, in general, is a method suitable for patients with severe to profound hearing loss in both ears who do not benefit from conventional hearing aids. This procedure can be beneficial for individuals with congenital or acquired severe to profound hearing loss. Through the surgical placement of these devices, even in cases of complete hearing loss, patients can perceive sounds.

What is a Cochlear Implant?

Also known as a bionic ear, a cochlear implant is an electronic medical device suitable for individuals experiencing severe or profound hearing loss. This device operates on the principle of electrically stimulating the nerves inside the inner ear.

Cochlear implants generally consist of two parts: a processor and a microphone, forming internal and external components. These components are placed behind the ear, under the scalp. The external microphone, resembling the microphone parts of hearing aids, can be removed and reattached as needed. The processor, also referred to as the processing unit, is surgically implanted into the inner ear. This internal component comprises two different sections: electrodes and a stimulator.

How Does a Cochlear Implant Work?

The operation of a cochlear implant begins with the microphone detecting, filtering, and processing sound. The filtered sound is digitized by the processor and then transmitted to the internal implant component. The implant converts this processed sound into electrical energy and subsequently delivers it to the electrode. Finally, the electrodes stimulate the nerves inside the ear with these electrical pulses, allowing the brain to perceive the sound.

What Sets Cochlear Implants Apart from Hearing Aids? Hearing aids amplify environmental sounds acoustically and convey these sounds to the ear with hearing loss. However, in cases of profound hearing loss, even if the sound is excessively amplified, it may not be perceived. In this regard, hearing aids fall short in cases of severe and profound hearing loss.

In such cases, the cochlear implant method can be beneficial. Implants convert sound waves into electrical energy and transmit them to the nerves inside the ear. This enables patients to perceive sounds even in cases of severe hearing loss. Another aspect that distinguishes cochlear implants from hearing aids is the surgical placement of implants into the inner ear.

Cochlear Implant Suitability Criteria:

Generally, individuals with significant damage to the inner ear, who do not benefit from hearing aids, and have intact inner ear nerves are considered suitable candidates for cochlear implants. The groups for whom this method can be applied include:

1. Individuals with severe, profound, or complete hearing loss
2. Children with congenital hearing loss
3. Individuals for whom hearing aids prove insufficient after inner ear diseases
4. Adults who experience acquired hearing loss due to various reasons such as diseases, accidents, and surgeries

For children, it is generally a requirement to be over 1 year old and have hearing loss in both ears. In adults, important criteria include a hearing threshold of at least 70 dB (decibels) and understanding speech at a maximum of 30%.

Stages of Cochlear Implantation:

The implementation of cochlear implants involves several stages:

● Preoperative Assessment: Before the surgery, candidates undergo a comprehensive examination by Ear, Nose, and Throat (ENT) specialists.

● Audiological Evaluation: Following the physical examination, an audiological assessment is conducted. Speech and sound audiometry methods are employed, particularly for assessing the speech abilities of young children. Evaluated children are compared with their peers of the same age with normal hearing abilities. Additionally, the use and impact of hearing aids are assessed.

● Decision on Hearing Device: Based on these evaluations, a decision is made on whether to use hearing aids or cochlear implantation. Generally, individuals are initially recommended to use hearing aids for a three-month period. In cases of profound hearing loss where no benefit is derived from hearing aids after this period, cochlear implantation is considered.

● Diagnostic Imaging: Magnetic Resonance Imaging (MRI) and ear tomography are requested to identify inner ear damages. Following radiological examinations, the overall health condition of patients is assessed, and the suitability for surgery is verified. Depending on the cause of hearing loss, an alternative procedure may be followed. Cases of congenital hearing loss undergo genetic evaluation.

● Cochlear Implant Surgery: After these assessments, cochlear implant surgery is performed. A small incision is made behind the ear to create space for implant placement. Subsequently, electrodes are inserted into the cochlea, also known as the inner ear.

● Intraoperative Checks: Before closing the incision, both the electrodes and the implant's proper functioning are verified. This operation, conducted under general anesthesia, typically takes 2-4 hours to complete.

● Postoperative Confirmation: After the patient recovers from anesthesia, the positions of the implant and electrodes are confirmed through radiological imaging.

● Activation of the Implant: Approximately four weeks after the cochlear implant surgery, the external component, including the microphone, is attached, and the implant is activated.

Factors Influencing Success in Cochlear Implantation:

The success of cochlear implantation is influenced by several factors:

● Duration of Hearing Loss: The duration of the hearing loss is a significant factor influencing the success of treatment. Generally, as the duration of hearing loss decreases, the chances of success tend to increase.

● Onset of Hearing Loss: The age at which hearing loss initially occurs is also crucial. Patients who have completed language development and acquired speech before the onset of hearing loss tend to achieve more favorable outcomes compared to those with congenital hearing loss.

● Age at Implantation: The age at which the cochlear implantation is performed holds importance. Overall, better results are typically observed in younger children.

● Number of Nerves in the Inner Ear: A higher number of nerves in the inner ear may contribute to the effectiveness of this method.