Longitudinal performance of an implantable vestibular prosthesis

Area of Science:

• Neuroscience
• Biomedical Engineering
• Ophthalmology

Background:

• Vestibular dysfunction significantly impacts quality of life.
• Current treatments for vestibular loss are limited.
• Implantable vestibular prostheses offer a potential solution by stimulating semicircular canal afferents.

Purpose of the Study:

• To longitudinally assess the efficacy of an implantable vestibular prosthesis in rhesus macaques.
• To investigate the long-term effects of electrical stimulation on the vestibulo-ocular reflex (VOR).
• To evaluate response variability across animals, surgeries, and semicircular canals.

Main Methods:

• Implantation of a vestibular prosthesis in rhesus macaques with intact vestibular end organs.
• Longitudinal study using brief biphasic pulse trains to stimulate semicircular canal afferents.
• Monitoring of electrical activation thresholds and elicited slow phase velocities over time.

Main Results:

• Electrical stimulation produced variable responses across canals and animals.
• Activation thresholds changed over time, generally decreasing.
• Elicited slow phase velocities were higher than those observed in human subjects.
• Response changes were not correlated with electrode impedance fluctuations.

Conclusions:

• Vestibular prosthesis efficacy varies, necessitating individualized transfer functions for optimal response.
• Responses may require remapping over time to maintain effectiveness.
• Further research is needed to refine prosthesis design and stimulation protocols for clinical application.