Auditory Brainstem Implant (ABI): Restoring Sound Awareness
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
An auditory brainstem implant (ABI) is a surgically implanted device that provides sound sensations to people with profound hearing loss caused by a missing or nonfunctioning auditory nerve or cochlea. [1] Unlike a cochlear implant, it bypasses the nerve to stimulate the brainstem directly. [1] It requires complex neurosurgery, and while results vary, it helps users recognize environmental sounds and improves lip-reading. [1]
What the research says
In people with NF2, ABI users understood speech best when sound was combined with lip-reading. A systematic review and single-arm meta-analysis of 33 studies found pooled estimates of 58% (95% CI 49–66%) for environmental sound discrimination and 55% (95% CI 40–69%) for closed-set discrimination. For open-set speech discrimination, the pooled estimate was 30% (95% CI 19–42%) with sound only, 46% (95% CI 37–54%) with lip-reading only, and 63% (95% CI 55–70%) with sound plus lip-reading. ABI-related complications were pooled at 33% (95% CI 15–52%) (PubMed: Wang et al., NeuroRehabilitation, 2024 [2]).
ABI users without a tumor tended to score higher on speech tests than users with a tumor. A systematic review of 36 studies covering 662 tumor and 267 non-tumor ABI users found a weighted mean open-set sentence recognition of 53.0% in non-tumor users versus 21.5% in tumor users, and a higher overall ranked-performance score for non-tumor users (3.5 vs 3.0, P = .04). The authors noted that standardized test scores alone were similar between the two groups (PubMed: Garcia et al., Otolaryngol Head Neck Surg, 2024 [3]).
In children with cochlear nerve deficiency, the ABI looks promising, but the evidence is still limited. A systematic review of 25 studies found that cochlear implants gave variable results and were limited in some cases, such as cochlear nerve aplasia, while the ABI (reported in only 4 of the 25 studies) appeared to be a promising alternative with better auditory, speech, and learning outcomes. The authors noted that robust evidence remains limited (PubMed: Alahmadi et al., Eur Arch Otorhinolaryngol, 2025 [4]).
What is an auditory brainstem implant (ABI)?
The auditory brainstem implant (ABI) represents a significant advancement in medical technology for individuals facing profound deafness that cannot be addressed by traditional means. The device is specifically engineered for those whose hearing loss stems from a missing or nonfunctioning inner ear (cochlea) or auditory nerve. By bypassing these damaged structures, the ABI delivers electrical signals directly to the cochlear nucleus complex, which is the hearing portion of the brainstem. [1]
The ABI system is comprised of two primary components that work in tandem to facilitate sound awareness. The external processor, worn on the ear or head, contains a microphone that captures environmental sounds and converts them into electrical signals. These signals are then transmitted to the internal implant, which consists of a receiver-stimulator placed under the skin and an electrode paddle positioned on the brainstem surface. [1]
Who is a candidate for an auditory brainstem implant?
Not every individual with hearing loss is a candidate for an ABI. The procedure is typically reserved for those with specific anatomical or neurological conditions where the auditory nerve is unable to transmit signals to the brain.
Candidate Category | Specific Conditions |
Genetic Disorders | Neurofibromatosis 2 (NF2) with acoustic neuromas. [1] |
Congenital Issues | Auditory nerve aplasia (missing nerve) or hypoplasia (underdeveloped nerve). [1] |
Inner Ear Malformations | Cochlear aplasia, hypoplasia, otosclerosis, or ossification. [1] |
Traumatic Injury | Severed auditory nerves due to temporal bone fractures. [1] |
While initially developed for adults with NF2, the application of ABI has expanded to include infants and children who are born without functioning auditory nerves.
How is an auditory brainstem implant different from a cochlear implant?
An auditory brainstem implant (ABI) and a cochlear implant both treat hearing loss with electrical stimulation, but they differ in their target area and surgical complexity.
Many people who refer to their hearing loss as 'nerve deafness' really have hearing loss arising from the cochlea. Check with your audiologist or ear, nose and throat doctor (ENT) before assuming you wouldn’t be a candidate for a cochlear implant. [1]
Feature | Cochlear Implant (CI) | Auditory Brainstem Implant (ABI) |
Target Area | Auditory Nerve | Brainstem (Cochlear Nucleus) |
Bypasses | Inner Ear (Cochlea) | Inner Ear and Auditory Nerve |
Surgical Complexity | Standard ENT surgery; often outpatient. | Complex neurosurgery; inpatient stay. [1] |
Prevalence | More commonly used. | Specialized; less common. |
What is the procedure for getting an auditory brainstem implant?
The journey toward receiving an ABI involves extensive pre-operative evaluation and a highly specialized surgical team. Before surgery, patients undergo behavioral hearing tests, communication evaluations, electrophysiologic testing, and advanced imaging such as CT and MRI scans to map the internal structures. [1]
The surgery itself is a collaborative effort involving neurosurgeons, neurotologists, anesthesiologists, and audiologists. [1] For patients with NF2, the implant is often placed during the same surgery performed to remove acoustic neuromas. [1] The internal electrode paddle must be precisely positioned on the brainstem surface, with audiologists performing real-time testing to ensure the device is functioning correctly. [1]
What are recovery and the long-term outlook after an auditory brainstem implant?
Following the neurosurgery, patients typically remain in the hospital for two to four days for monitoring. [1] The device is not activated immediately; instead, the surgical team waits several weeks for healing to occur before the external processor is programmed and turned on.
The outcomes of an ABI vary significantly between individuals. [1] While the device cannot restore “natural” hearing, most users experience a meaningful improvement in their daily lives.
Key outcomes include:
Sound Awareness: Ability to detect environmental sounds like doorbells or traffic. [1]
Lip-Reading Enhancement: Significant improvement in the ability to understand speech when combined with visual cues. [1]
Speech Recognition: Some users, particularly children implanted at a young age, may achieve word and sentence recognition. [1]
Conclusion
The auditory brainstem implant is a vital technology for those with profound hearing loss who have no other options for sound restoration. By bypassing the auditory nerve and stimulating the brainstem directly, the ABI provides a pathway for sound awareness and improved communication. While the procedure involves complex neurosurgery and results can vary, the potential for enhanced lip-reading and environmental sound recognition offers a significant life improvement for eligible candidates.
Frequently Asked Questions
1. What is the main difference between an ABI and a cochlear implant?
A cochlear implant stimulates the auditory nerve, while an ABI bypasses the nerve to stimulate the brainstem directly. ABIs are used when the auditory nerve is missing or nonfunctional.
2. Can an ABI restore normal hearing?
No, an ABI provides a sensation of sound rather than normal hearing. It helps with sound awareness, identification, and significantly improves lip-reading abilities.
3. Who is the ideal candidate for an auditory brainstem implant?
Ideal candidates are individuals with profound hearing loss due to a missing or damaged auditory nerve or cochlea, such as those with NF2 or congenital nerve absence.
4. How long is the hospital stay after ABI surgery?
Most patients stay in the hospital for two to four days after the procedure, though this may be longer depending on the individual's condition and the complexity of the surgery.
5. When is the device activated after surgery?
The ABI is typically activated and programmed several weeks after the surgery to allow the surgical site to heal properly.
6. Is ABI surgery performed on children?
Yes, ABIs can be implanted in infants and children who are born without functioning auditory nerves or with severe inner ear malformations.
7. What specialists are involved in the surgery?
The surgical team usually includes a neurosurgeon, a neurotologist (ear surgeon), an anesthesiologist, and audiologists to test the device during placement.
8. Can I wear the ABI processor while sleeping?
No, the external processor is typically removed while sleeping, similar to a hearing aid or cochlear implant processor.
9. What are the risks of the procedure?
As with any complex brain surgery, risks include cerebrospinal fluid leaks and other neurological complications. Outcomes are also difficult to predict precisely.
10. Does an ABI help with word recognition?
While results vary, some users—especially children implanted early—can achieve word and sentence recognition, though many primarily use it to aid lip-reading.
Related Reading
Cochlear Implants: How They Work, Who They Help, and What Recovery Looks Like explains how cochlear implants work and who they help.
Acoustic Neuroma (Vestibular Schwannoma): What It Is, Symptoms, Causes, and Treatment Options describes the hearing nerve tumor that can lead to an ABI.
Hearing Loss: Symptoms, Causes, and Treatment Options reviews the types and causes of hearing loss and treatments.
What Is Auditory Neuropathy? Symptoms, Causes, and Treatment explains a hearing disorder where sound signals fail to reach the brain.
References
Cleveland Clinic. Auditory Brainstem Implant: What it Is, Placement & Procedure. Cleveland Clinic. Apr. 11, 2022. https://my.clevelandclinic.org/health/treatments/22723-auditory-brainstem-implant
Wang B, Yan M, Liu C, et al. Auditory brainstem implants for hearing rehabilitation in NF2-schwannomatosis: A systematic review and single-arm meta-analysis. NeuroRehabilitation. 2024;54(2):213-225. PMID 38427506. https://doi.org/10.3233/NRE-230198
Garcia A, Haleem A, Poe S, et al. Auditory brainstem implant outcomes in tumor and nontumor patients: A systematic review. Otolaryngol Head Neck Surg. 2024;170(6):1648-1658. PMID 38329219. https://doi.org/10.1002/ohn.662
Alahmadi A, Abdelsamad Y, AlAmari NA, et al. Hearing implants in pediatrics with cochlear nerve deficiency: an updated systematic review. Eur Arch Otorhinolaryngol. 2025;282(5):2203-2215. PMID 39658661. https://doi.org/10.1007/s00405-024-09087-w
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.
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