Today’s blog is the final installment in our series exploring the 3 types of implantable hearing devices – cochlear implants, bone-anchored implants (BAI), and brainstem and middle ear implants. Today, we’re covering brainstem and middle ear implants.
These final two types of implants are far less common than cochlear implants and bone-anchored implants. First, let’s learn about middle ear implants.
What is a middle ear implant?
To understand a middle ear implant, you must first be familiar with the middle ear structures. They are the tympanic membrane, the ossicles (malleus, incus and stapes), the Eustachian tube, the round window and oval window, along with many muscles, veins and the blood supply.
A middle ear implant is a surgically implanted device in the middle ear space that is generally coupled to a middle ear structure. It works by mechanically oscillating to facilitate cochlear stimulation (Wolfe, 2018).
Who is a candidate for a middle ear implant?
Adults, 18 years and older, with moderate-to-severe sensorineural hearing loss and normal middle ear anatomy. Conductive or mixed hearing losses are not good candidates (Wolfe, 2018).
Advantages of the middle ear implant:
- Some middle ear implants are fully implantable, so they are visually more appealing
- There is no concern of an occlusion (feeling of fullness in the ear) effect or feedback
- These implants work 24/7
- There is a decreased risk of reaction for those with allergies or intolerance to earmold/dome materials and improved comfort
Disadvantages of the middle ear implant may include:
- Surgical placement and healing time
- Risk of ossicular disarticulation (a condition where the small bones [ossicles] in the middle ear become separated or disconnected from each other)
- Increased financial expense
- Unable to verify performance (no Real-Ear Measurements) and not compatible with MRIs (Wolfe, 2018)
- Middle ear implants are not covered by Medicare, Medicaid or private insurance (BCBS, 2010)
Semi implantable vs fully implantable middle ear implants
There is only one fully implantable device currently FDA approved, the Envoy Medical Esteem device. All components are implanted under the skin, so the device is not visible (Envoy Medical, 2024).
Semi-implantable devices are more common and have an external portion that functions like a traditional hearing aid. One example is the Ototronix Maxum device, which is FDA approved.
Auditory Brainstem Implants
Now let’s discuss the final device in our series, the brainstem implant, or ABI. These are surgically implanted auditory prostheses that bypass the inner ear structures to stimulate the cochlear nucleus complex in the brainstem. These are the most uncommon implantable devices.
Who qualifies for an auditory brainstem implant?
According to FDA regulations, people 12 years and older with Neurofibromatosis Type 2 (NF2) are approved candidates; as of the year 2000, tumor removal and implant placement occur in the same surgery.
At the time of this blog, Cochlear was the only company with a device that is approved by the FDA. Med EL has one that is approved in Europe (Wolfe, 2018) (Cleveland Clinic, 2024).
What is Neurofibromatosis Type 2 (NF2)?
Neurofibromatosis Type 2 (NF2) is a rare condition that causes tumors to grow on nerves, most commonly on the vestibulocochlear nerve, but also on other nerves of the head and spine. It is a genetic condition that can be passed down. When these tumors occur on the 8th cranial nerve, they are called either vestibular schwannoma or acoustic neuroma (Johns Hopkins University, 2025).
Parts of an auditory brainstem implant
These devices have an external portion and internal portion; the internal implant is shaped like a paddle. The surgery is completed by a team of surgeons, including neurosurgeons, a neuro-otologist, an electrophysiologist, an anesthesiologist, and an audiologist.
Auditory brainstem implants are currently undergoing FDA reviews for implantation in children who have other VIII cranial nerve abnormalities. These implants are usually only useful for sound awareness and do not provide clarity of speech, but users can experience sentence or word recognition. They are also used for severe to profound sensorineural hearing loss for patients who do not qualify for a traditional cochlear implant. Results of ABI surgery vary widely (Cleveland Clinic, 2024).
Sources
Middle Ear Implants | Hearing Loss Alternatives | Envoy Medical
Blue Cross Blue Shield of North Carolina. (2010)
Wolfe, J. (2018). Cochlear Implants: Audiologic Management and Considerations for Implantable Hearing Devices. San Diego, CA: Plural Publishing
Auditory Brainstem Implant: What it Is, Placement & Procedure, Cleveland Clinic 2024 Neurofibromatosis Type 2 (NF2) | Johns Hopkins Medicine 2025
