Continuous vestibular implant stimulation partially restores eye-stabilizing reflexes

Area of Science:

• Neuroscience
• Biomedical Engineering
• Otolaryngology

Background:

• Bilateral vestibular loss causes vision impairment, instability, and falls, with limited treatment options.
• Current rehabilitation is insufficient for some patients with vestibular dysfunction.
• Restoring vestibular sensation via implants is a promising therapeutic avenue.

Purpose of the Study:

• To evaluate a novel multichannel vestibular implant system for continuous, long-term stimulation.
• To assess the system's ability to selectively stimulate semicircular canals and drive vestibulo-ocular reflex (VOR).
• To investigate the safety and efficacy of vestibular prosthetics in humans with bilateral vestibular loss.

Main Methods:

• Four human subjects with bilateral vestibular loss received unilateral implantation of a multichannel vestibular implant.
• Continuous, 24-hour, motion-modulated prosthetic stimulation was delivered to the 3 semicircular canals.
• Binocular 3D vestibulo-ocular reflex (VOR) oculography was used to measure responses to stimulation.

Main Results:

• Prosthetic stimulation induced transient nystagmus, followed by stable VOR responses over extended periods (350-812 days).
• Stimulation targeting individual canals produced VOR responses aligned with the canal's axis.
• Responses scaled with stimulus intensity and aligned with the intended 3D head motion axis.

Conclusions:

• The vestibular implant selectively and continuously stimulates all 3 semicircular canals in patients with bilateral vestibular loss.
• The system drives reflexive VOR eye movements that approximate 3D head motion.
• This technology offers a potential new treatment for disabling vestibular dysfunction.