Vestibular Implant Imaging

Electrical stimulation of vestibular afferent neurons to partially restore semicircular canal sensation of head rotation and the stabilizing reflexes that sensation supports has potential to effectively treat individuals disabled by bilateral vestibular hypofunction. Ideally, a vestibular implant system using this approach would be integrated with a cochlear implant, which would provide clinicians with a means to simultaneously treat loss of both vestibular and auditory sensation. Despite obvious similarities, merging these technologies poses several challenges, including stimulus pulse timing errors that arise when a system must implement a pulse frequency modulation-encoding scheme (as is used in vestibular implants to mimic normal vestibular nerve encoding of head movement) within fixed-rate continuous interleaved sampling (CIS) strategies used in cochlear implants. Pulse timing errors caused by temporal discretization inherent to CIS create stair step discontinuities of the vestibular implant’s smooth mapping of head velocity to stimulus pulse frequency. In this study, we assayed electrically evoked vestibuloocular reflex responses in two rhesus macaques using both a smooth pulse frequency modulation map and a discretized map corrupted by temporal errors typical of those arising in a combined cochlear-vestibular implant. Responses were measured using three-dimensional scleral coil oculography for prosthetic electrical stimuli representing sinusoidal head velocity waveforms that varied over 50–400°/s and 0.1–5 Hz. Pulse timing errors produced negligible effects on responses across all canals in both animals, indicating that temporal discretization inherent to implementing a pulse frequency modulation-coding scheme within a cochlear implant’s CIS fixed pulse timing framework need not sacrifice performance of the combined system’s vestibular implant portion. NEW & NOTEWORTHY Merging a vestibular implant system with existing cochlear implant technology can provide clinicians with a means to restore both vestibular and auditory sensation. Pulse timing errors inherent to integration of pulse frequency modulation vestibular stimulation with fixed-rate, continuous interleaved sampling cochlear implant stimulation would discretize the smooth head velocity encoding of a combined device. In this study, we show these pulse timing errors produce negligible effects on electrically evoked vestibulo-ocular reflex responses in two rhesus macaques.

Download Full-text

Restoring the High-Frequency Dynamic Visual Acuity with a Vestibular Implant Prototype in Humans

Audiology and Neurotology ◽

10.1159/000503677 ◽

2019 ◽

Vol 25 (Suppl. 1-2) ◽

pp. 91-95 ◽

Cited By ~ 6

Author(s):

Dmitrii Starkov ◽

Nils Guinand ◽

Florence Lucieer ◽

Maurizio Ranieri ◽

Samuel Cavuscens ◽

...

Keyword(s):

Visual Acuity ◽

High Frequency ◽

Horizontal Plane ◽

Head Impulse Test ◽

Dynamic Visual Acuity ◽

Bilateral Vestibulopathy ◽

Vestibular Implant ◽

Functional Benefit ◽

Head Impulses ◽

Near Future

Introduction: The vestibular implant could become a clinically useful device in the near future. This study investigated the feasibility of restoring the high-frequency dynamic visual acuity (DVA) with a vestibular implant, using the functional Head Impulse Test (fHIT). Methods: A 72-year-old female, with bilateral vestibulopathy and fitted with a modified cochlear implant incorporating three vestibular electrodes (MED-EL, Innsbruck, Austria), was available for this study. Electrical stimulation was delivered with the electrode close to the lateral ampullary nerve in the left ear. The high-frequency DVA in the horizontal plane was tested with the fHIT. After training, the patient underwent six trials of fHIT, each with a different setting of the vestibular implant: (1) System OFF before stimulation; (2) System ON, baseline stimulation; (3) System ON, reversed stimulation; (4) System ON, positive stimulation; (5) System OFF, without delay after stimulation offset; and (6) System OFF, 25 min delay after stimulation offset. The percentage of correct fHIT scores for right and left head impulses were compared between trials. Results: Vestibular implant stimulation improved the high-frequency DVA compared to no stimulation. This improvement was significant for “System ON, baseline stimulation” (p = 0.02) and “System ON, positive stimulation” (p < 0.001). fHIT scores changed from 19 to 44% (no stimulation) to maximum 75–94% (System ON, positive stimulation). Conclusion: The vestibular implant seems capable of improving the high-frequency DVA. This functional benefit of the vestibular implant illustrates again the feasibility of this device for clinical use in the near future.

Download Full-text

A comprehensive study of NEMS-based piezoresistive gyroscopes for vestibular implant systems

2017 IEEE International Symposium on Inertial Sensors and Systems (INERTIAL) ◽

10.1109/isiss.2017.7935665 ◽

2017 ◽

Cited By ~ 1

Author(s):

S. Dellea ◽

A. Longoni ◽

G. Langfelder ◽

A. Nikas ◽

O. Leman ◽

...

Keyword(s):

Vestibular Implant ◽

Comprehensive Study

Download Full-text

Vestibular Implant: Are We Ready for It?

International Journal of Advanced and Integrated Medical Sciences ◽

10.5005/jp-journals-10050-10057 ◽

2016 ◽

Vol 1 (4) ◽

pp. 183-185

Author(s):

Abhinav Srivastava

Keyword(s):

Research And Development ◽

Present Article ◽

Surgical Intervention ◽

Negative Impact ◽

Vestibular Function ◽

Human Studies ◽

Bilateral Vestibulopathy ◽

Technical Feasibility ◽

Vestibular Implant

ABSTRACT The present article aims to provide an overview of the research and development in the field of vestibular implants for patients suffering from bilateral vestibulopathy. There is a strong justification for surgical intervention in such patients because of a negative impact and disability of disease on the life of the patients. A few animal and human studies have been undertaken, and the available data from both animal and human studies are encouraging. It is evident that there is a technical feasibility for the use of vestibular implants. Although normal vestibular function is not expected, significant, physical improvement is expected in these patients. How to cite this article Mohan C, Srivastava A. Vestibular Implant: Are We Ready for It? Int J Adv Integ Med Sci 2016; 1(4):183-185.

Download Full-text