A totally implantable cochlear implant (TICI) is a hearing device with all its components placed under the skin, making it completely invisible. Unlike conventional cochlear implants, a TICI functions continuously without any external hardware. The device is designed to provide a hearing solution for individuals with specific types of severe hearing loss.
Defining the Technology: Components and Function
A TICI operates by capturing, processing, and transmitting sound signals entirely beneath the skin. A subcutaneous microphone detects sound waves through the skin, using algorithms to reduce interference from the body’s own noises like breathing or chewing.
The sound is converted into a digital signal and sent to an internal processor. This component analyzes the sound and transforms it into electrical pulses. These pulses are then delivered to an electrode array threaded into the cochlea, the spiral-shaped part of the inner ear.
The electrical signals from the electrode array directly stimulate the auditory nerve, bypassing damaged parts of the ear. The brain receives these neural impulses and interprets them as sound. This allows the user to perceive their auditory environment.
Key Differences from Conventional Cochlear Implants
The primary distinction between a TICI and a conventional cochlear implant is hardware location. Traditional systems are semi-implantable, requiring a visible audio processor behind the ear that houses the microphone and power source. A TICI integrates all elements into a single, internal device, making it invisible.
With no external parts, a TICI offers discretion and eliminates self-consciousness associated with visible hearing devices. The lack of external components also means nothing needs to be removed for activities like swimming, showering, or sleeping. This allows for continuous hearing, unlike conventional implants where the external processor must be removed to prevent damage.
The microphone’s placement also impacts sound gathering. A traditional implant’s external processor captures sound directly from the air, while a TICI’s subcutaneous microphone detects sound that has passed through the skin. Feasibility studies have shown that TICI hearing performance is comparable to traditional implants, with similar outcomes in speech perception tests.
Candidacy and Surgical Considerations
Candidacy criteria for a TICI align with those for conventional systems. Candidates have severe-to-profound hearing loss in one or both ears that hearing aids cannot address. An evaluation, including hearing tests and imaging scans, confirms the hearing loss stems from inner ear damage and that the auditory nerve is intact.
The surgical procedure is similar to standard cochlear implant surgery but is more extensive. The surgeon must create a space under the skin for the single integrated unit containing the processor, battery, and microphone. This is in addition to placing the electrode array into the cochlea.
Anatomical characteristics are considered to ensure there is sufficient space for the device and an effective location for the microphone. The surgeon positions the device securely so the overlying skin can heal properly. After a recovery period, an audiologist activates and programs the implant to the user’s needs.
Operational Aspects and Lifestyle Implications
The device is powered by an implanted, rechargeable battery. To recharge it, the user places an external charging coil over the implant, held by a magnet, often while sleeping. This process uses a transcutaneous energy transfer system.
This design eliminates handling disposable batteries or removing a processor for charging. Battery life and charging schedules depend on the device and usage. A remote control or smartphone app allows users to adjust settings, change volume, and check battery status.
A significant long-term consideration is technology upgrades. With conventional implants, a user can get new features by swapping their external processor. Because all TICI components are internal, any hardware upgrade to the processor or battery requires another surgery to replace the implant.
Availability and Technological Horizon
The availability of TICIs is limited, as the technology is in advanced development and clinical evaluation. As of early 2025, some devices have received regulatory approval in certain regions, like a CE mark in Europe, but are not widely available. The first TICI surgery in Europe was part of a clinical study in 2020.
Manufacturers like MED-EL and MicroPort are developing TICI systems. Feasibility studies show a strong safety profile and hearing outcomes comparable to traditional implants. The technology is still in the research phase and not yet commercially available in markets like the United States pending FDA review.
Ongoing research focuses on enhancing device performance and longevity. Areas of innovation include improving the internal microphone’s sensitivity and noise-cancellation to provide more natural sound quality. Researchers are also working to extend battery life and streamline the wireless charging process.