Influence of Floating-Mass Transducer Coupling Efficiency for Active Middle-Ear Implants on Speech Recognition

OBJECTIVE:The efficiency of vibroplasty (coupler-floating mass transducer [FMT] assembly) can be monitored by direct stimulation of the inner ear through the active middle-ear implant system and comparison of the vibroplasty in vivo threshold and the postoperative bone-conduction pure-tone threshold. The aim of this study was to compare the vibroplasty in vivo threshold with the postoperative speech recognition in patients with a high preoperative maximum word recognition score. STUDY DESIGN:Retrospective cohort study of German-speaking patients implanted with a vibrating ossicular prosthesis (VORP) 502 or VORP 503 and high preoperative maximum word recognition score between the years of 2011 and 2015. SETTING:Multicenter study of four German centers. PATIENTS:Twenty-three active middle-ear implant users. INTERVENTION:Rehabilitative. MAIN OUTCOME MEASURES:Bone-conduction pure-tone and vibroplasty thresholds, postoperative aided word recognition score (WRS) at 65 dB SPL (sound pressure level) and preoperative maximum WRS with Freiburg monosyllabic words. RESULTS:The mean postoperative aided WRS at 65 dB SPL was 82%. An increasing difference between vibroplasty thresholds and bone-conduction thresholds was associated with a higher discrepancy between the unaided maximum WRS and the postoperative aided WRS. Only if this difference was less than 20 dB, an articulation index of 0.5 (WRS = 75%) or more was achieved. CONCLUSIONS:Audiological outcome after vibroplasty depends on the coupling efficiency reflected by the vibroplasty threshold.