Vestibular Implantation to Treat Adult-Onset Bilateral Vestibular Hypofunction

Inclusion Criteria:

1. Adults age 22-90 years diagnosed with ototoxic, idiopathic ornon-ototoxic/non-central bilateral vestibular hypofunction inadequately responsiveto vestibular rehabilitation for greater than 1 year as determined by pre-inclusionhistory, vestibular testing and clinical examination conducted by a board-certifiedneurotologist, neurologist or other physician skilled in diagnosis of vestibulardisorders

2. Hearing status: (1) Hearing in the candidate ear for implantation is equivalent toor worse than that in the contralateral ear; and (2) hearing in the contralateralear is good enough to allow functional communication in case hearing in theimplanted ear is lost after implantation. Specifically, the contralateral ear mustsatisfy all of the following criteria:

3. 0.5/1/2/4 kHz pure-tone-average threshold (PTA) hearing better than (i.e., lessthan) 70 dB HL; and

4. ear-specific sentence recognition score using the recorded AzBio Sentence Testpresented at 60 dB SPL-A in quiet must be >60% when tested under either theunaided condition or, if 0.5/1/2/4 kHz PTA>50 dB, the best-aided condition; and

5. ear-specific word recognition score using the recordedConsonant-Nucleus-Consonant (CNC) Word Recognition Test presented at 60 dBHL inquiet must be >60% when tested under either the unaided condition or, if 0.5/1/2/4 kHz PTA>50 dB, the best-aided condition

6. Caloric responses consistent with severe or profound bilateral loss of labyrinthinefunction, as indicated by one or more of the following: (a) summed speed of caloricresponses to warm and cool supine caloric stimuli totaling <10°/sec per ear for eachof both ears; (b) summed speed of ice water caloric responses during supine andprone head orientation tests totaling <10°/sec per ear for each of both ears; or (c)speed of ice water caloric responses during supine head orientation tests <5°/secper ear for each of both ears, with a lack of nystagmus reversal on quickly flippingfrom supine to prone

7. Prior MRI imaging of the brain, internal auditory canals and cerebellopontine (CP)angle showing a patent labyrinth, present vestibular nerve, patent cochlea, presentcochlear nerve, and absence of internal auditory canal/cerebellopontine angle tumorsor other central causes of vestibulo-ocular reflex dysfunction or sensorineuralhearing loss

8. Prior CT imaging of the temporal bones showing a facial nerve canal with normalcaliber and course, middle ear without evidence of chronic otitis media or tympanimembrane perforation or cholesteatoma, a mastoid cavity with adequate aeration forsurgical access to each semicircular canal, skull thickness ≥3 mm at the plannedwell site, and scalp soft tissue thickness ≤7 mm. This criterion may be satisfiedwithout additional imaging if an existing head CT or MRI already demonstrates thosefindings

9. Vaccinations as recommended per Johns Hopkins Cochlear Implant Center and UnitedStates Centers for Disease Control and Prevention protocols to reduce the risk ofmeningitis in subjects undergoing cochlear implantation, as described at this site:https://www.cdc.gov/vaccines/vpd/mening/public/dis-cochlear-faq-gen.html

10. Motivated to travel to the study center, to undergo testing and examinationsrequired for the investigational study, and to participate actively in a vestibularrehabilitation exercise regimen

11. The participant must agree not to swim or to use or operate vehicles, heavymachinery, powered tools or other devices that could pose a threat to theparticipant, to others, or to property throughout the duration of participation inthe study and until at least 1 month after final deactivation of the MVI Implant

Exclusion Criteria:

1. Inability to understand the procedures and the potential risks involved asdetermined by study staff

2. Inability to participate in study procedures due to blindness, ≤ ±10° neck range ofmotion, cervical spine instability, ear canal stenosis or malformation sufficient toprevent caloric testing

3. Diagnosis of acoustic neuroma/vestibular schwannoma, chronic middle ear disease,cholesteatoma, or central nervous system causes of vestibulo-ocular reflexdysfunction, including chronic and continuing use of medications, drugs or alcoholat doses sufficiently great to interfere with vestibular compensation

4. Vestibular dysfunction known to be caused by reasons other than labyrinthine injurydue to ototoxicity, ischemia, trauma, infection, Meniere's disease, or geneticdefects known to act on hair cells

5. Lack of labyrinth patency or vestibular nerve as determined by MRI of the brain withattention to the internal acoustic meatus

6. Any contraindication to the planned surgery, anesthesia, device activation anddeactivation, or participation in study assessments, as determined by the surgeon,anesthesiologist, or designee, including known intolerance of any materials used inany component of the investigational devices that will come in contact with thesubject

7. History of myocardial infarction, coronary bypass surgery, or any percutaneouscoronary intervention (PCI) within 6 months prior to screening

8. Orthopedic, neurologic or other nonvestibular pathologic conditions of sufficientseverity to confound posture and gait testing or other tests used in the study toassay vestibular function.

9. Subjects with estimated glomerular filtration rate (GFR) < 30 ml/min (MDRD formula)at screening

10. Subjects with heart failure NYHA class III or IV

11. Subjects with Child-Pugh class C cirrhosis

12. Inadequately treated or unstable depression, suicidality as indicated by anyaffirmative answer to the 6-question screener version of the Columbia SuicideSeverity Rating Scale (C-SSRS), or any other psychiatric disease or substance abusehistory likely to interfere with protocol compliance

13. Contraindications to scleral coil eye movement testing, including monocularblindness and a history of fainting vagal reactions to prior eye manipulations wouldexclude subjects from eye coil testing

14. Inability to tolerate baseline testing protocols

15. Recent corneal injury

16. A history of cervical spine disease preventing head rotation

17. A history of fainting or vagal reactions prior to eye manipulations that wouldpreclude 3D eye movement coil testing

18. Pregnancy, positive urine or serum pregnancy test at any time during studyparticipation,

19. Ability to become pregnant combined with failure or refusal to consistently use ahighly effective method of contraception from at least 1 month prior to implantationto not before 1 month after both device deactivation and conclusion of studyparticipation. Highly effective contraception methods include: Total abstinence. Periodic abstinence (e.g., calendar, ovulation, symptothermal,post ovulation methods) and withdrawal are not acceptable methods of contraceptionfor purposes of defining exclusion criteria for this study Female sterilization (surgical bilateral oophorectomy with or without hysterectomy) or tubal ligation atleast six weeks before entering the study. A woman who has undergone oophorectomywithout hysterectomy may participate in the study only after her reproductive statushas been confirmed by subsequent hormone level assessment For female subjects ofchild-bearing potential, study participation is not excluded if the studycandidate's male partner is the sole partner of the study candidate and has beenvasectomized. Combination of any two of the following: Use of oral, injected or implanted hormonal methods of contraception or other formsof hormonal contraception that have comparable efficacy (failure rate <1%), forexample, hormone vaginal ring or transdermal hormone contraception Placement of anintrauterine device (IUD) or intrauterine system (IUS) Barrier methods ofcontraception: Condom or Occlusive cap (diaphragm or cervical/vault caps) withspermicidal foam/gel/film/cream/vaginal suppository In case of use of oralcontraception, women should have been stabile on the same pill for a minimum of 3months before taking study treatment.

20. Women who are nursing/lactating

21. Any medical condition, judged by the investigator team, that is likely to interferewith a study candidate's participation in the study or likely to cause seriousadverse events during the study.