A New Flexible Auditory Brainstem Implant

An auditory brainstem implant (ABI) provides the sensation of sound to individuals who are deaf due to neurofibromatosis 2 (NF2) or a severely compromised or absent cochlea and/or auditory nerve. ABIs work by bypassing the cochlea and the eighth nerve and stimulating the cochlear nucleus of an individual’s brainstem. 

Historically, ABIs have had stiff electrodes that do not match the brainstem’s shape well, which is believed to limit the effectiveness of stimulation. It is reported that most ABI users gain sound awareness but little assistance with speech intelligibility. 

Researchers from Mass Eye and Ear, in collaboration with several scientists from Geneva, Switzerland, have been working on a new, more flexible ABI for over a decade. It consists of an elastic multilayer structure containing ultra-thin platinum electrodes embedded in silicone, allowing the implant to closely conform to the curved surface of the brainstem (Trouillet et al., 2025). 

Researchers note that, while cochlear implants, which stimulate the auditory nerve, have been life-changing for many individuals who are d/Deaf and hard of hearing, there remains a group of individuals for whom current technology falls short. “This new research lays the foundation for an ABI that could improve hearing outcomes and reduce side effects for this group” (Technology Networks, 2025). 

References

Trouillet, A., Revol, E., Coen, FV. et al. High-resolution prosthetic hearing with a soft auditory brainstem implant in macaques. Nat. Biomed. Eng (2025).

Technology Networks. (2025, May 16). Flexible brainstem implant may restore hearing when cochlear implants can’t.