An invisible cochlear implant, also known as a totally implantable cochlear implant (TICI), is a hearing device where every component operates from under the skin. It assists individuals with significant hearing loss by electronically stimulating the auditory nerve. Unlike conventional devices, the TICI is completely unseen, offering a functional and cosmetically discreet solution with no external hardware.
How Invisible Cochlear Implants Work
A subcutaneous microphone, which is a tiny, highly sensitive sensor, is implanted in a location such as the posterior wall of the external auditory canal. This microphone detects sound vibrations that travel through the body’s tissues. The development of microphones that can effectively capture external sounds while filtering out internal body noises, like breathing or movement, has been a focus of research.
Once sound is detected, the signal is sent to an internal sound processor that converts the acoustic information into electrical pulses. These pulses are then transmitted to an electrode array, a delicate wire carefully inserted into the cochlea of the inner ear. The electrodes along this array deliver the electrical signals directly to the auditory nerve fibers, bypassing damaged parts of the ear. The brain interprets these signals as sound, allowing the user to perceive their environment.
The entire system is powered by an implanted, rechargeable battery. This battery requires periodic charging, which is accomplished transcutaneously by transferring power through the skin without wires. A user will place an external charging unit on their head, for instance while sleeping, which inductively couples with the internal battery. Some designs may also utilize a remote control or smartphone application to manage settings or check battery status.
Comparison to Traditional Cochlear Implants
Unlike traditional cochlear implants that have an external sound processor worn behind the ear, a TICI integrates all components internally. Traditional devices use an external unit for the microphone, processor, and transmitter coil. A TICI places all of these functions into a single, implanted device.
With no external equipment, users gain convenience and freedom. They do not need to put on or take off a device daily. Activities such as swimming, showering, or participating in contact sports become possible without interrupting hearing.
The aesthetic aspect is a factor for many individuals, as an unseen device can alleviate feelings of self-consciousness. It also eliminates the daily maintenance associated with external components, such as cleaning or protecting them from moisture. The ability to hear 24/7, even during sleep, offers a continuous connection to the auditory world.
The Surgical and Activation Process
Receiving a TICI involves a surgical procedure performed under general anesthesia. A surgeon makes a small incision behind the ear to create a space for the internal components. The main body of the device, including the processor and battery, is secured, and the electrode array is threaded into the cochlea. The specialized subcutaneous microphone is also positioned during this procedure.
Following surgery, a healing period of one to four weeks is required for the incision to heal, during which the implant remains inactive. Once the surgical site has recovered, the patient returns for an activation appointment with an audiologist. This is when the device is turned on for the first time.
The activation process involves programming the sound processor to meet the individual’s hearing needs. The audiologist adjusts settings and maps the electrodes to different sound frequencies to create an effective listening experience. This initial programming is just the beginning, as follow-up appointments are required to fine-tune the settings as the brain adapts. Patients are also instructed on how to use the external charger.
Determining Candidacy
Eligibility for a TICI is based on a specific set of criteria, much like traditional cochlear implants. The primary candidates are adults who have severe-to-profound sensorineural hearing loss in both ears. This type of hearing loss originates in the inner ear, or cochlea, and means that conventional hearing aids do not provide adequate benefit.
Audiological evaluations are conducted to confirm that a person struggles with speech understanding, even with powerful hearing aids. Medical assessments are also performed to ensure a candidate is in good overall health and can undergo surgery. Anatomical considerations, such as the structure of the cochlea and the thickness of the skull bone, are evaluated through imaging scans.
The length of time a person has experienced hearing loss can also influence outcomes. Individuals who lost their hearing after developing speech and language skills often adapt more readily to the implant.
Current Status and Availability
TICI technology represents an advanced stage of hearing device development, but it is not yet widely available. These devices are in clinical trial phases worldwide to gather data on safety, effectiveness, and long-term reliability. For example, the first implantation of a TICI in Europe occurred in September 2020 as part of a clinical study.
Researchers are actively working to refine TICI systems. A primary focus is enhancing the longevity and efficiency of the implantable rechargeable battery to ensure the device remains effective for many years.
As of now, TICIs have not received widespread regulatory approval, such as from the U.S. Food and Drug Administration (FDA), for commercial use. While the technology holds promise, it remains an investigational device accessible primarily to participants in research studies.