Vestibular implant: Difference between revisions

Neural prosthesis to improve balance

A vestibular implant (VI) is a neural prosthesis aiming to regain vestibular functions among people who suffer from permanent balance problems, especially with conditions such as bilateral vestibulopathy. To improve balance, a VI device uses electrical stimulation. This provides the VI an opportunity to directly stimulate vestibular nerves. Thus, implant can transfer necessary vestibular information to the vestibular nerves even though the peripheral inner ear balance organs are damaged. The implants have been shown to improve balance and quality of life in some trials. However, there is no commercial VI device yet as it is still in investigational phase.

Currently, there are two distinctive vestibular implant types in human trials, targeting one of the two types of sensors in the vestibular system, otolith organs in the utricle and saccule, and cupulas in the three semicircular canals.^[1] Components of VI devices show differences based on the specialization of peripheral vestibular structures. The peripheral vestibular system end-organs are crucial to encode the space orientation which consists of both angular and linear perception. Semicircular canals encode angular accelerations while otolith organs, which are saccule and utricle, transform vertical and horizontal accelerations into neural signals. In the basis of structural differences and distinct placements and planes of vestibular end-organs, current VI devices use different methods and placements regarding recreation of the functions of impaired peripheral vestibular organs.

The close anatomical relationship between the cochlea peripheral organ responsible for encoding hearing and the vestibular end-organs currently prevents placement of a vestibular implant alone. As implantation surgery carries a risk of hearing loss, investigational device designs now focus on combined systems that integrate both cochlear and vestibular implants to support hearing and balance functions.^[2]

A systematic review published in 2019 found several studies which demonstrated the feasibility of the technology.^[3]

In 2021 the New England Journal of Medicine published the results of a study conducted at Johns Hopkins Hospital in which 8 participants with bilateral vestibular hypofunction had a device surgically inserted. Outcomes measured after 6 months and 1 year after the implantation of the device showed generally positive outcomes, including vestibular function and quality of life. However, hearing was reduced in all but one participant.^[4]

The BionicVest Project started in 2018 with funding by the EU as a consortium including University of Las Palmas, Cochlear, University of Sapienza, University of Navarra, and European Institute for ORL Antwerp.^[5] The vestibular implant of BionicVest group focuses on restoring the vestibular function with otolith-organ electrode placement where it is especially near the saccule. This approach includes three more electrodes in addition to cochlear implant electrodes aiming to stimulate otolith-organ-originated nerve fibers as well as cochlear nerve. They reported reappearance of VEMP responses which are electrophysiological measurements of otolith organ functions after the VI insertion.^[6][7] Moreover, research group also reported more postural stability, better gait performance, and improved quality of life in BVP patients who had otolith-originated vestibular implant. The first phase of project ended in 2022.^[6]
From 2023, a new phase of BionicVest has started which is named as BionicVest2 with a consortium including Cochlear, University of Navarra, European Institute for ORL Antwerp, and Radboudumc. BionicVest2 website described the aim of second phase as bringing commercially viable high-technology solution for severe vestibular disorders.^[8]