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Vibrant Med-El Soundbridge Implantable Hearing System

Vibrant Med-El Soundbridge Implantable Hearing System. David Schramm MD FRCSC University of Ottawa Department of Otolaryngology Grand Rounds September 14, 2007. Vibrant Soundbridge Middle Ear Implant. Conventional Indication: Moderate to severe SNHL Direct drive technology

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Vibrant Med-El Soundbridge Implantable Hearing System

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  1. Vibrant Med-El Soundbridge Implantable Hearing System David Schramm MD FRCSC University of Ottawa Department of Otolaryngology Grand Rounds September 14, 2007

  2. Vibrant Soundbridge Middle Ear Implant • Conventional Indication: • Moderate to severe SNHL • Direct drive technology • Health Canada and FDA Approval • Zinc air battery • (1week)

  3. History • Developed in 1996 by Symphonix • FDA approved in 2000 • First ME prosthesis to obtain FDA approval • Canadian implant centre: Ottawa • Purchased by MED-EL in 2003

  4. Amplification vs. Direct Drive • Amplification: • Occlusion, insertion loss, feedback • Direct drive: • Mechanical energy delivered directly to the ossicles • Reduces many of acoustic issues inherent in amplification

  5. Direct Drive Advantages • Clearer, more natural sound • Improved hearing in difficult environments • Reduction of feedback • No occlusion effect • Open ear canal for comfort • Improved cosmetics

  6. Soundbridge Components Audio Processorreceiver Vibrating Ossicular Prosthesis (VORP) implant Conductor Link Detail of Floating Mass Transducer Floating Mass Transducer

  7. VORP - Vibrating Ossicular Prosthesis

  8. Vibrant Med-El SoundbridgeImplantation – Left Ear The FMT should be in close contact and parallel to the stapes

  9. Conventional Indications • Adults (18+) with bilateral moderate - severe SNHL • Discrimination score > 50% • Normal middle ear anatomy • Conventional amplification unsuitable • Realistic expectations

  10. Chronic otitis externa Exostosis Eczema or psoriasis Allergies Stenotic canal Absence of the pinna Mandibular fractures Excessive wax production Excessive perspiration Conditions That May Preclude Conventional Amplification

  11. Conventional Use - Contraindications • Conductive hearing loss • Active middle ear infection • Tympanic membrane perforation • Progressive or sudden hearing loss • Retrocochlear or central auditory disorder • Skin condition precluding use of Audio Processor

  12. 125 125 250 250 500 500 1000 1000 2000 2000 4000 4000 8000 8000 0 10 20 30 40 50 60 70 80 90 100 110 3 months post Presurgery Residual Hearing @ 3 Months Frequency (Hz) • Vibrant Soundbridge did not significantly change residual hearing • Mean thresholds at preop and 3 months postop n=53 • 2 patients decrease in PTA (12 dB, 18 dB) Hearing Level (dB HL)

  13. Residual Hearing @ 12 Months • Long-term US data shows that residual hearing is maintained • N= 63 patients C. Leutje, MD et. al., Phase III Clinical Trial results with the Vibrant Soundbridge: A Prospective Controlled Multicenter Study, Feb. 2002

  14. 100 Hearing Aid Vibrant Soundbridge* 12 Months 90 80 70 60 50 40 30 20 10 0 Familiar Talkers Ease of Reverberation Reduced Cues Background Aversiveness of Distortion of Global Communication Noise Sounds Sound *statistically significant Hearing Aid vs. Soundbridge at 3 Months and 12 Months (n = 94) Profile of Hearing Aid Performance Situations Without Problems (%) PHAP Subscales Source: Luetje, et al 2002

  15. Vibrant Med-El Soundbridge:Expanding Indications • Sensorineural hearing loss • Conductive hearing loss • Mixed hearing loss

  16. Vibrant Soundbridge Placement Classic • FMT is clipped onto the long process of the incus

  17. Vibrant Soundbridge Placement FMT and PORP • FMT in conjunction with a Kurz partial prosthesis and attachment clip

  18. Vibrant Soundbridge Placement FMT and TORP • FMT in conjunction with a Kurz total prosthesis and attachment clip

  19. Vibrant Soundbridge Placement FMT and Stapedectomy Piston • FMT in conjunction with standard prosthesis

  20. Vibrant Soundbridge Placement FMT on the Round Window • FMT is placed in the RW niche

  21. Vibrant Soundbridge:Expanding Indications Limits (dB HL) 500 1000 1500 2000 3000 4000 BC Lower Limit 0 0 0 0 0 0 CHL/Mixed BC UL 45 50 55 65 65 -- SNHL Upper Limit 65 75 80 80 85 85

  22. Comparison of Vibrant Soundbridge device and Revision Ossiculoplasty In Patients with Conductive Hearing Loss due to Chronic Otitis Media: A Randomized Controlled Trial

  23. Current Standard Therapy • ossiculoplasty utilizing a total ossicular replacement prosthesis (TORP) placed between the mobile stapes footplate and the tympanic membrane

  24. Ossiculoplasty -“successful” result • improvement in the conductive component of the hearing loss to 20 dB or less • “as treated” success rate of initial TORP ossiculoplasty at 1 year: • range: 27% - 78% • median: 53.3% Zenner 2001, Black 1990, House 2001, Wehrs 1994, Murakami 1995, Bayazit 1999, Brackmann 1984, Jackson 1983, Mangham 1990, Slater 1997, Rondini-Gilli 2003, Colletti 1987, Truy 2007, Schmerber 2006 • “as treated” success rate of revision ossiculoplasty: 40%

  25. Ossiculoplasty -“successful” result • “as treated” success rate of initial TORP ossiculoplasty at 5 years: • range: 28% - 64% • median: 36% Colletti 1987, Yung 2006, Farrior 1996, Shinohara 2000, Vartiainen 1992, Grote 1990 5-10% risk of extrusion of ossiculoplasty prosthesis

  26. Vibrant Soundbridge Round Window Placement • first described by Colletti in 2005 • only experience with round window placement in Europe • systematic review identified 2 independent studies • comprising 10 patients in total (Colletti 2006, Opie 2006) • - one study conducted by the manufacturer • All 10 patients had successful improvement of their hearing loss using the American Academy of Otolaryngology – Head and Surgery Committee on Hearing and Equilibrium criteria.

  27. Study Objective • Purpose: compare round window placement of VSB with revision ossiculoplasty in patients with significant conductive hearing loss due to chronic otitis media who are not suitable for conventional amplification (hearing aid) • Null hypothesis: round window placement of VSB will have same likelihood of hearing improvement as revision ossiculoplasty • Alternative hypothesis: round window placement of the VSB will result in greater likelihood of hearing improvement than revision ossiculoplasty

  28. Randomization (blocks of varying size) Revision ossiculoplasty Vibrant Med-El Soundbridge 16 weeks - Evaluation Randomized Controlled unblinded Phase III Clinical Trialcomparing the Vibrant Soundbridge device with revision TORP ossiculoplasty. Personnel assessing the hearing outcome will be blinded. Adults with absent stapes who previously underwent unsuccessful ossiculoplasty surgery with conductive hearing loss component > 30 dB Stratification (12 strata): Previous ossiculoplasty: 1 vs. 2 or more Degree of Sensorineural hearing loss: None vs. Mild vs. Moderate Study sites: 2

  29. Stratification • Subjects will be stratified (12 strata) at randomization by: • Previous ossiculoplasty surgery (1 vs. 2 or more) • Degree of Sensorineural hearing loss: (None vs. Mild vs. Moderate) • Study sites: 2 (single surgeon at each site) • Permuted block randomization (blocks of varying size) will be performed within strata.

  30. Patient Population: Inclusion criteria • Adults with conductive hearing loss > 30 decibels (dB) • Absent stapes at previous unsuccessful ossiculoplasty surgery • Etiology of the conductive component of hearing loss is chronic otitis media • Subjects are not suitable for conventional amplification (hearing aid) • Documented external auditory canal irritation (otitis externa) or intolerable hearing aid occlusion effect noted during previous hearing aid trial will be considered the only valid reasons for determining that conventional amplification is unsuitable

  31. Patient Population: Exclusion criteria • Age less than 18 years • Stapes footplate fixation identified at previous ossiculoplasty • Tympanic membrane perforation or active middle ear/mastoid infection noted at initial evaluation for determining study eligibility • Dissatisfaction with a hearing aid for cosmetic reasons is not considered a valid reason for determining that conventional amplification is unsuitable

  32. Primary outcome: • Proportion of subjects with a conductive hearing loss component < 20 dB at 16 weeks post-intervention • Audiometric evaluation will be performed by a certified audiologist who is blinded to the type of surgical intervention

  33. Definition: Post-intervention conductive hearing loss component • Difference between post-surgery air conduction thresholds with VSB device activated and post-surgery bone conduction thresholds measured at 500Hz, 1000 Hz, 2000 Hz, and 3000 Hz • Method is compatible with guidelines of American Academy of Otolaryngology – Head and Surgery Committee on Hearing and Equilibrium. (Monsell 1995)

  34. Secondary Outcome: • Analysis of Safety Data including surgical complications • Infection • Hemorrhage • sensorineural hearing loss • facial nerve injury

  35. Tertiary Outcomes: • Patient responses from Glasgow Benefit Inventory standardized patient questionnaire administered at 16 weeks post-intervention (Robinson, 1996) • To facilitate acceptance of this study design by the otologic surgical community, an exploratory “as treated” analysis will be performed • Long term efficacy and safety data: The study is projected to last 2 years. Patients who volunteer for long-term assessment will participate in a registry and will be followed for up to 10 years. Audiometric evaluation will be performed at 6 months, 1 year, 18 months, 2 years, and annually thereafter.

  36. Success rate: conventional ossiculoplasty • Median: 53.3% at 1 year post-surgery • Reported findings quite optimistic due to “as treated” analyses performed and differential loss to follow-up • Revision ossiculoplasty surgery typically is less successful than primary surgery For study planning, this conservative estimate of the effectiveness of conventional therapy is used

  37. Success rate: Round Window Placement of VSB • All 10 patients (100%) had successful improvement of their hearing loss using standard criteria after round window placement of VSB • Presumably, this is a highly selected group of patients • Unlikely this success rate could be reproduced in the general patient population.

  38. Success rate: Round Window Placement of VSB • A much more conservative success rate of 80% would be anticipated

  39. Acceptance by Otologic Community • Otologic surgeons and their patients would not consider an implantable hearing aid instead of revision ossiculoplasty unless the rate of success is substantial • Surgical implantation of a hearing aid is more invasive procedure • Slightly increased risks of infection, hemorrhage, sensorineural hearing loss and facial nerve injury with implantation of VSB • Slight risk of failure of the internal component of the device necessitating revision surgery

  40. Acceptance by Otologic Community • The otologic community would likely require a success rate of at least 80% before surgical implantation of a hearing aid would be considered in this circumstance.

  41. Sample Size Calculation • 96 adults (48 in each group) needed to detect 27% absolute difference (from 53% to 80%) in proportion of patients with improvement of conductive hearing loss component to < 20 dB between conventional revision TORP ossiculoplasty and VSB groups with 80% power using two-sided p = 0.05 level test • Includes 2% increase in sample size calculation (2 additional subjects) to preserve power allowing for two interim analyses as calculated using the Lan-DeMets method of O’Brien-Fleming stopping rules University of British Columbia Sample Size Calculator http://newton.stat.ubc.ca/~rollin/stats/ssize/b2.html

  42. Data and Safety Monitoring Committee (DSMC) • Independent group (exclusive of the investigators) to assess progress of study • Review conduct of the study, safety data, and the two planned interim analyses of efficacy Adverse events such as surgical complications and device failures closely monitored • Recommend discontinuation of the study if early evidence of excessive benefit or harm

  43. Interim Analyses: Rationale • Success rate of revision ossiculoplasty when analyzed on the “intent-to-treat” principle may well be less than the estimate used to calculate sample size • Success rate of the VSB device may be understated • Since sample size estimates are particularly sensitive to variations in the probability of success of the VSB, the study may be discontinued after an interim analysis or the sample size revised, as appropriate.

  44. Interim Analyses • Two equally spaced interim analyses will be performed • Lan-DeMets method of the O’Brien-Fleming stopping boundaries: • Initial analysis - performed at 33% recruitment nominal p value of 0.00021 • Second interim analysis - performed at 67% recruitment nominal p value of 0.0121 If observed probability of success of VSB is 0.90, study may be terminated after second interim analysis on recommendation of DSMC

  45. Statistical Analysis • Primary analysis: Comparison of proportions of success of the 2 treatment groups utilizing logistic regression (adjusting for randomization stratification factors) • An intent-to-treat analysis of the primary endpoint will be performed. • Demographic data will be compared using Pearson Chi-Square test or Fisher’s exact test as appropriate for categorical data and Student’s t-test or Wilcoxon test for continuous data depending on the normality of the data. These analyses will be considered descriptive.

  46. Statistical Analysis • Exploratory data analysis will be performed of the continuous data obtained from the standardized patient questionnaire administered at 16 weeks post-intervention, the Glasgow Benefit Inventory. • Analysis of Safety Data: Analysis of surgical complications (including infection, hemorrhage, sensorineural hearing loss, and facial nerve injury) will be performed. • Kaplan-Meier estimates of the time distribution of any device failures will be calculated. These analyses will be considered descriptive.

  47. Major Ethical Issues • Potential Risks: Both revision TORP ossiculoplasty and implantation of VSB in a conventional fashion are current standards of surgical care. Although the incidence of complications due to otologic surgery is very low, there is potentially slightly increased risk of sensorineural hearing loss with round window implantation of VSB although this has not occurred in uncontrolled European trials. • Potential Benefits: Round window placement of the VSB is expected to result in a greater probability of hearing improvement than revision ossiculoplasty. • Equipoise: No studies have compared the success of conventional revision TORP ossiculoplasty with round window placement of the Vibrant Soundbridge in a controlled fashion in this patient population.

  48. Limitations • Rarely in the otologic surgical literature have ‘intent-to-treat’ analyses been performed • An exploratory “as treated” analysis is necessary to facilitate acceptance of this study design by the otologic surgical community • As this is the initial Phase III study, the surgical procedures will be performed by only one surgeon at each of the two institutions. • If this study demonstrates that round window placement of VSB results in a greater probability of hearing improvement than revision ossiculoplasty, a subsequent Phase III trial would be proposed with multiple surgeons to evaluate the generalizability of the initial finding.

  49. Study time table • Protocol Development:2 months • IRB application for RCT and approval: 3 months • Patient recruitment & data entry: 24 months • 2 clinics • 25 patients in each clinic per year • Data Analysis & Manuscript Preparation: 1 month • Total:2½ years

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