Vestibular Implantation to Treat Adult-Onset Bilateral Vestibular Hypofunction

Johns Hopkins University8 enrolled

Overview

Although cochlear implants can restore hearing to individuals who have lost cochlear hair cell function, there is no widely available, adequately effective treatment for individuals suffering chronic imbalance, postural instability and unsteady vision due to bilateral vestibular hypofunction. Prior research focused on ototoxic cases has demonstrated that electrical stimulation of the vestibular nerve via a chronically implanted multichannel vestibular implant can partially restore vestibular reflexes that normally maintain steady posture and vision; improve performance on objective measures of postural stability and gait; and improve patient-reported disability and health-related quality of life. This single-arm open-label study extends that research to evaluate outcomes for up to 8 individuals with non-ototoxic bilateral vestibular hypofunction, yielding a total of fifteen adults (age 22-90 years at time of enrollment) divided as equally as possible between ototoxic and non-ototoxic cases.

There is no adequately effective treatment for individuals suffering chronic imbalance, postural instability and unsteady vision due to loss of semicircular canal function despite vestibular rehabilitation exercises. The experience of seven adults with bilateral vestibular hypofunction due to ototoxicity who underwent unilateral surgical placement of a vestibular implant and have received continuously motion-modulated electrical stimulation of the vestibular nerve for \>6 months revealed that this approach can partially restore vestibular sensation and reflexes that normally maintain steady posture and vision. This study will examine long-term outcomes in that cohort and extend vestibular implant treatment to adults with idiopathic or non-ototoxic/non-central bilateral vestibular hypofunction. Within constraints on power and/or minimum detectable effect size due to limits on the number of study participants permitted under IDE G150198 and U01DC019364, the study will test the following hypotheses regarding unilateral vestibular implantation, activation and long-term (≥8 week) continuous/daily use: 1. It is feasible, as quantified by implantation being achieved in all subjects undergoing attempted implantation surgery. 2. It is safe, as determined by incidence of serious unanticipated adverse device-related events and as further quantified by proportions of: 1. implanted ears with preservation of 4-frequency pure tone average for 0.5,1,2,4 kHz air-conducted audiometric detection thresholds ≤ 50 dB HL and ear-specific speech discrimination ≥50% (consistent with Class A or B per American Academy of Otolaryngology-Head and Neck Surgery 1995 guidelines13 ) or ≤ 30 dB change from preoperative baseline (if preoperative baseline is ≥20 dBHL) and ear-specific speech discrimination ≤30% worse than preoperative baseline (if preoperative baseline is ≤80%) 2. participants with preservation of useful sound-field hearing by the above criteria, and 3. implanted ears with preservation of otolith endorgan function, if present pre-operatively 3. It is tolerable, as quantified by ≥6 mo duration of compliance with use. 4. It is efficacious, as defined by nonzero improvement with respect to preoperative baseline in Vestibular Implant Composite Outcome score (VICO), which incorporates vestibulo-ocular reflex gain during passive head impulse rotation (VHITG); postural stability as quantified by the Bruininks-Oseretsky Test of Motor Proficiency, 2nd Edition Balance Subtest 5 (BOT); gait stability as quantified by Dynamic Gait Index (DGI); Dizziness Handicap Inventory (DHI); and SF-6D health utility (SF6DU).

Eligibility

Sex: ALLMin age: 22 YearsMax age: 90 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Adults age 22-90 years diagnosed with ototoxic, idiopathic or non-ototoxic/non-central bilateral vestibular hypofunction inadequately responsive to vestibular rehabilitation for greater than 1 year as determined by pre-inclusion history, vestibular testing and clinical examination conducted by a board-certified neurotologist, neurologist or other physician skilled in diagnosis of vestibular disorders 2. Hearing status: (1) Hearing in the candidate ear for implantation is equivalent to or worse than that in the contralateral ear; and (2) hearing in the contralateral ear is good enough to allow functional communication in case hearing in the implanted ear is lost after implantation. Specifically, the contralateral ear must satisfy all of the following criteria: 1. 0.5/1/2/4 kHz pure-tone-average threshold (PTA) hearing better than (i.e., less than) 70 dB HL; and 2. ear-specific sentence recognition score using the recorded AzBio Sentence Test presented at 60 dB SPL-A in quiet 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; and 3. ear-specific word recognition score using the recorded Consonant-Nucleus-Consonant (CNC) Word Recognition Test presented at 60 dBHL in quiet 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 3. Caloric responses consistent with severe or profound bilateral loss of labyrinthine function, as indicated by one or more of the following: (a) summed speed of caloric responses to warm and cool supine caloric stimuli totaling \<10°/sec per ear for each of both ears; (b) summed speed of ice water caloric responses during supine and prone 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°/sec per ear for each of both ears, with a lack of nystagmus reversal on quickly flipping from supine to prone 4. Prior MRI imaging of the brain, internal auditory canals and cerebellopontine (CP) angle showing a patent labyrinth, present vestibular nerve, patent cochlea, present cochlear nerve, and absence of internal auditory canal/cerebellopontine angle tumors or other central causes of vestibulo-ocular reflex dysfunction or sensorineural hearing loss 5. Prior CT imaging of the temporal bones showing a facial nerve canal with normal caliber and course, middle ear without evidence of chronic otitis media or tympani membrane perforation or cholesteatoma, a mastoid cavity with adequate aeration for surgical access to each semicircular canal, skull thickness ≥3 mm at the planned well site, and scalp soft tissue thickness ≤7 mm. This criterion may be satisfied without additional imaging if an existing head CT or MRI already demonstrates those findings 6. Vaccinations as recommended per Johns Hopkins Cochlear Implant Center and United States Centers for Disease Control and Prevention protocols to reduce the risk of meningitis in subjects undergoing cochlear implantation, as described at this site: https://www.cdc.gov/vaccines/vpd/mening/public/dis-cochlear-faq-gen.html 7. Motivated to travel to the study center, to undergo testing and examinations required for the investigational study, and to participate actively in a vestibular rehabilitation exercise regimen 8. The participant must agree not to swim or to use or operate vehicles, heavy machinery, powered tools or other devices that could pose a threat to the participant, to others, or to property throughout the duration of participation in the 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 as determined by study staff 2. Inability to participate in study procedures due to blindness, ≤ ±10° neck range of motion, cervical spine instability, ear canal stenosis or malformation sufficient to prevent caloric testing 3. Diagnosis of acoustic neuroma/vestibular schwannoma, chronic middle ear disease, cholesteatoma, or central nervous system causes of vestibulo-ocular reflex dysfunction, including chronic and continuing use of medications, drugs or alcohol at doses sufficiently great to interfere with vestibular compensation 4. Vestibular dysfunction known to be caused by reasons other than labyrinthine injury due to ototoxicity, ischemia, trauma, infection, Meniere's disease, or genetic defects known to act on hair cells 5. Lack of labyrinth patency or vestibular nerve as determined by MRI of the brain with attention to the internal acoustic meatus 6. Any contraindication to the planned surgery, anesthesia, device activation and deactivation, or participation in study assessments, as determined by the surgeon, anesthesiologist, or designee, including known intolerance of any materials used in any component of the investigational devices that will come in contact with the subject 7. History of myocardial infarction, coronary bypass surgery, or any percutaneous coronary intervention (PCI) within 6 months prior to screening 8. Orthopedic, neurologic or other nonvestibular pathologic conditions of sufficient severity to confound posture and gait testing or other tests used in the study to assay 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 any affirmative answer to the 6-question screener version of the Columbia Suicide Severity Rating Scale (C-SSRS), or any other psychiatric disease or substance abuse history likely to interfere with protocol compliance 13. Contraindications to scleral coil eye movement testing, including monocular blindness and a history of fainting vagal reactions to prior eye manipulations would exclude 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 would preclude 3D eye movement coil testing 18. Pregnancy, positive urine or serum pregnancy test at any time during study participation, 19. Ability to become pregnant combined with failure or refusal to consistently use a highly effective method of contraception from at least 1 month prior to implantation to not before 1 month after both device deactivation and conclusion of study participation. Highly effective contraception methods include: Total abstinence. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post ovulation methods) and withdrawal are not acceptable methods of contraception for purposes of defining exclusion criteria for this study Female sterilization (surgical bilateral oophorectomy with or without hysterectomy) or tubal ligation at least six weeks before entering the study. A woman who has undergone oophorectomy without hysterectomy may participate in the study only after her reproductive status has been confirmed by subsequent hormone level assessment For female subjects of child-bearing potential, study participation is not excluded if the study candidate's male partner is the sole partner of the study candidate and has been vasectomized. Combination of any two of the following: Use of oral, injected or implanted hormonal methods of contraception or other forms of hormonal contraception that have comparable efficacy (failure rate \<1%), for example, hormone vaginal ring or transdermal hormone contraception Placement of an intrauterine device (IUD) or intrauterine system (IUS) Barrier methods of contraception: Condom or Occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/vaginal suppository In case of use of oral contraception, women should have been stabile on the same pill for a minimum of 3 months before taking study treatment. 20. Women who are nursing/lactating 21. Any medical condition, judged by the investigator team, that is likely to interfere with a study candidate's participation in the study or likely to cause serious adverse events during the study.

Outcomes

Primary Outcomes

PM1.1: Dynamic Gait Index (DGI) during motion-modulated implant stimulation at 6 months post-implantation, relative to pre-operative baseline, aggregated across all implant users.

DGI comprises 8 gait tasks scored by an examiner: walking on a level surface, changing gait speed, walking during horizontal head turns, walking during vertical head turns, pivoting, stepping over an obstacle, stepping around obstacles, and waling up and down stairs. Each task is scored (0-3 points, 3 is best). Raw DGI score is the sum of the eight subtest scores and ranges from 0 to 24, with higher scores meaning better outcome and minimally important difference 3.2 points.

Time frame: Pre-intervention to 6 months post-implantation

PM1.2: Gain (VHITG) of the vestibulo-ocular reflex, as measured using the video head impulse test averaged for the three implanted semicircular canals, relative to pre-operative baseline, aggregated across all implant users.

During video head impulse testing (vHIT), rotational eye and head movement are measured by a goggle-mounted camera and motion sensor during brief, fast \~10 degree head rotations about the axis of a semicircular canal being tested. Performance is quantified by vestibulo-ocular reflex (VOR) gain, which a ratio of eye movement to head movement (in this case the integral of eye velocity relative to the head and the additive inverse of the integral of head velocity, respectively). VHITG, the average vHIT VOR gain for each of the three semicircular canals of the implanted ear, typically ranges from 0 to 1, with higher numbers indicating better performance.

Time frame: Pre-intervention to 6 months post-implantation

Secondary Outcomes

EM1.1: Vestibular Implant Composite Outcome (VICO) score at 6 months post-implantation, relative to pre-operative baseline, aggregated for all implanted participants.

Vestibular Implant Composite Outcome (VICO) score incorporates changes in vestibulo-ocular reflex gain during video head impulse testing, postural stability, gait, dizziness handicap, and health-related quality of life at 6 months post-implantation, relative to pre-operative baseline. VICO (t=6months post-op) score is the sum of changes, from preoperative baseline to 6 months post-implantation, in vestibulo-ocular reflex gain during passive head impulse rotation (VHITG); postural stability as quantified by the Bruininks-Oseretsky Test of Motor Proficiency, 2nd Edition Balance Subtest 5 (BOT); gait stability as quantified by Dynamic Gait Index (DGI); Dizziness Handicap Inventory (DHI); and SF6D health utility (SF6DU); with each component's contribution scaled to the corresponding test's minimally important difference (MID). Score 0-100, higher scores indicate better outcomes.

Time frame: Pre-intervention to 6 months post-implantation

EM1.2: Bruininks-Oseretsky Test of Motor Proficiency 2nd Edition Balance Subtest 5 (BOT) score 6 months post-implantation, relative to pre-operative baseline, aggregated for all implanted participants.

BOT comprises 9 postural tasks scored by an examiner: standing with both feet on a line, standing on one leg, tandem walking, walking on a line with eyes open and eyes closed, and standing on a balance beam. Each task is performed twice and scored (0-4 points, 4 is best). The BOT score is the sum of the best scores for each task. It ranges from 0 to 36 points, with higher scores meaning better outcome and minimally important difference 4.5 points.

Time frame: Pre-intervention to 6 months post-implantation

EM1.3: Dizziness Handicap Inventory (DHI) score at 6 months post-implantation, relative to pre-operative baseline, aggregated for all implanted participants.

Dizziness Handicap Inventory (DHI) is a 25-question survey designed to quantify self-rated disability due to dizziness and unsteadiness, with scores ranging from 0 (least disabled, best outcome) to 100 (worst outcome). The minimally important difference is 18 points.

Time frame: Pre-intervention to 6 months post-implantation

EM1.4: SF6D utility (SF6DU) score at 6 months post-implantation, relative to pre-operative baseline, aggregated for all implanted participants.

SF6DU is a unitless health utility score computed from patient-reported replies to the SF6 health-related quality of life survey and ranging from 0 to 1, with higher scores meaning better outcome and minimally important difference 0.03 points.

Time frame: Pre-intervention to 6 months post-implantation

EM2.1: Vestibular Implant Composite Outcome (VICO) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have non-ototoxic/non-central adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM2.2: Bruininks-Oseretsky Test of Motor Proficiency 2nd Edition Balance Subtest 5 (BOT) score 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have non-ototoxic/non-central adult-onset BVH

BOT includes 9 postural tasks scored by an examiner: standing with both feet on a line, standing on one leg, tandem walking, walking on a line with eyes open and eyes closed, and standing on a balance beam. Each task is performed twice and scored (0-4 points). The BOT score is the sum of the best scores for each task. It ranges from 0 to 36 points, with higher scores meaning better outcome and minimally important difference 4.5 points.

Time frame: Pre-intervention to 6 months post-implantation

EM2.3: Dizziness Handicap Inventory (DHI) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have non-ototoxic/non-central adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM2.4: SF6D utility (SF6DU) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have non-ototoxic/non-central adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM2.5: Dynamic Gait Index (DGI) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have non-ototoxic/non-central adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM2.6: Gain (VHITG) of the vestibulo-ocular reflex, measured using the vHIT averaged for the three implanted semicircular canals, relative to pre-operative baseline, for the subgroup of participants who have non-ototoxic/non-central adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM3.1: Vestibular Implant Composite Outcome (VICO) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have ototoxic adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM3.2: Bruininks-Oseretsky Test of Motor Proficiency 2nd Edition Balance Subtest 5 (BOT) score 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have ototoxic adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM3.3: Dizziness Handicap Inventory (DHI) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have ototoxic adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM3.4: SF6D utility (SF6DU) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have ototoxic adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM3.5: Dynamic Gait Index (DGI) score at 6 months post-implantation, relative to pre-operative baseline, for the subgroup of participants who have ototoxic adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

EM3.6: Gain (VHITG) of the vestibulo-ocular reflex, measured using the video head impulse test averaged for the three implanted semicircular canals, relative to pre-operative baseline, for the subgroup of participants who have ototoxic adult-onset BVH

Time frame: Pre-intervention to 6 months post-implantation

SM0.1: Type of unanticipated adverse device effects as of 6 months post-implantation

Time frame: Pre-intervention to 6 months post-implantation

SM0.2: Incidence of unanticipated adverse device effects as of 6 months post-implantation

Assess safety of the intervention, aggregating data across all implanted participants (diversified across ototoxic and non-ototoxic/non-central adult-onset BVH), as determined by incidence of adverse device-related events from pre-intervention to 6 months post-implantation

Time frame: Pre-intervention to 6 months post-implantation

SM0.3: Severity of unanticipated adverse device effects as of 6 months post-implantation

Assess safety of the intervention, aggregating data across all implanted participants (diversified across ototoxic and non-ototoxic/non-central adult-onset BVH), as determined by severity of adverse device-related events from pre-intervention to 6 months post-implantation

Time frame: Pre-intervention to 6 months post-implantation

SM1.1: Changes in implant-side bone-conduction 4-frequency (0.5, 1, 2, 4 kHz) pure tone average detection threshold (BonePTAi), aggregated across all implant users

BonePTAi is the 4-frequency average of pure tone detection thresholds, in dBHL, for implant-side bone-conduction presentation of pure tones at 0.5, 1, 2 and 4 kHz. Range is -10 to 80 dBHL, with change toward smaller absolute values representing better (closer to normal) outcome.