Evolution of the candidacy requirements and patient perioperative assessment protocols for cochlear implantation.

Cochlear implantation as an approved clinical therapy ushered in an exciting era of innovation for the treatment of hearing loss. The U.S. Food and Drug Administration approved the use of cochlear implants as a treatment option for adults with profound sensorineural hearing loss in 1985. The landscape for treating adults and children with significant hearing loss has changed dramatically over the last three decades. The purpose of this paper is to examine the evolving regulatory process and changes to clinical care. A significant emerging trend in cochlear implantation is the consideration of steroids to preserve hearing during and following surgery. This parallels the quest for hearing preservation in noise-induced hearing disorders, especially considering the current interest in biological drug therapies in this population. The future will likely usher in an era of combination therapeutics utilizing drugs and cochlear implantation. For over 30+ years and following regulatory compliance, the Rocky Mountain Ear Center has developed an extensive candidacy and outcome assessment protocol. This systematic approach evaluates both unaided and aided auditory performance during candidacy stages and post-implantation. Adjunctive measures of cognition and quality-of-life augment the auditory assessment in specific populations. Practical insights into lessons learned have directed further clinical research and have resulted in beneficial changes to clinical care.

Comprehensive hearing aid assessment in adults with bilateral severe-profound sensorineural hearing loss who present for Cochlear implant evaluation.

PURPOSE: To comprehensively assess and describe functional auditory performance in a group of adults with bilateral, moderate sloping to profound sensorineural hearing loss who were dissatisfied users of well-fit bilateral hearing aids and presented for Cochlear implant evaluation. Participants were evaluated with bilateral hearing aids and after six months of bimodal (Cochlear implant and a contralateral hearing aid) hearing experience with a Cochlear implant and contralateral hearing aid. METHODS: Study participants were assessed using pure tone audiometry, aided speech understanding in quiet (CNC words) and in noise (AzBio sentences at +10 and +5 dB SNR) in the sound field with unilateral and bilateral hearing aids fit to target. Participants completed subjective scales of quality of life, (Health Utilities Index Mark 3), hearing disability, (Speech, Spatial and Qualities of Hearing Scale) and a device use satisfaction scale. Participants ≥55 years were administered the Montreal Cognitive Assessment screening tool. One-hundred enrolled individuals completed baseline evaluations. RESULTS: Aided bilateral mean speech understanding scores were 28% for CNC words and 31%, and 17% for AzBio sentences at a +10 dB, and +5 dB SNR, respectively. Mean scale ratings were 0.46 for overall quality of life and 3.19 for functional hearing ability. Ninety percent of participants reported dissatisfaction with overall hearing performance. CONCLUSIONS: Evaluation results, including functional performance metrics quantifying the deleterious effects of hearing loss for overall wellbeing, underscore that bilateral hearing aids are not an effective treatment for individuals with bilateral, moderate sloping to profound sensorineural hearing loss. Individuals with this degree of hearing impairment, who demonstrate poor aided speech understanding and dissatisfaction with hearing abilities in everyday life, require timely referral to a Cochlear implant clinic for further evaluation.

Benefits of Cochlear Implantation for Single-Sided Deafness: Data From the House Clinic-University of Southern California-University of California, Los Angeles Clinical Trial.

OBJECTIVES: Cochlear implants (CIs) have been shown to benefit patients with single-sided deafness (SSD) in terms of tinnitus reduction, localization, speech understanding, and quality of life (QoL). While previous studies have shown cochlear implantation may benefit SSD patients, it is unclear which point of comparison is most relevant: baseline performance before implantation versus performance with normal-hearing (NH) ear after implantation. In this study, CI outcomes were assessed in SSD patients before and up to 6 mo postactivation. Benefits of cochlear implantation were assessed relative to binaural performance before implantation or relative to performance with the NH ear alone after implantation. DESIGN: Here, we report data for 10 patients who completed a longitudinal, prospective, Food and Drug Administration-approved study of cochlear implantation for SSD patients. All subjects had severe to profound unilateral hearing loss in one ear and normal hearing in the other ear. All patients were implanted with the MED-EL CONCERTO Flex 28 device. Speech understanding in quiet and in noise, localization, and tinnitus severity (with the CI on or off) were measured before implantation (baseline) and at 1, 3, 6 mo postactivation of the CI processor. Performance was measured with both ears (binaural), the CI ear alone, and the NH ear alone (the CI ear was plugged and muffed). Tinnitus severity, dizziness severity, and QoL were measured using questionnaires administered before implantation and 6 mo postactivation. RESULTS: Significant CI benefits were observed for tinnitus severity, localization, speech understanding, and QoL. The degree and time course of CI benefit depended on the outcome measure and the reference point. Relative to binaural baseline performance, significant and immediate (1 mo postactivation) CI benefits were observed for tinnitus severity and speech performance in noise, but localization did not significantly improve until 6 mo postactivation; questionnaire data showed significant improvement in QoL 6 mo postactivation. Relative to NH-only performance after implantation, significant and immediate benefits were observed for tinnitus severity and localization; binaural speech understanding in noise did not significantly improve during the 6-mo study period, due to variability in NH-only performance. There were no correlations between behavioral and questionnaire data, except between tinnitus visual analog scale scores at 6 mo postactivation and Tinnitus Functional Index scores at 6 mo postactivation. CONCLUSIONS: The present behavioral and subjective data suggest that SSD patients greatly benefit from cochlear implantation. However, to fully understand the degree and time course of CI benefit, the outcome measure and point of comparison should be considered. From a clinical perspective, binaural baseline performance is a relevant point of comparison. The lack of correlation between behavioral and questionnaire data suggest that represent independent measures of CI benefit for SSD patients.

Hearing Outcomes after Revision Stapedectomy Managed with Total Ossicular Prostheses.

OBJECTIVES: (1) To describe the use of total ossicular prostheses (TOPs) in the setting of stapedectomy requiring an incus bypass procedure. (2) To analyze the short- and long-term audiometric results of TOP utilization in the setting of stapedectomy for an incus bypass procedure. STUDY DESIGN: Case series with chart review. SETTING: Tertiary neurotologic referral center. SUBJECTS AND METHODS: Seventeen cases of TOP reconstruction after stapedectomy were performed due to advanced incus erosion. The cases were assessed for pre- and postoperative bone conduction and air conduction pure-tone averages (PTAs; 0.5, 1, 2, 3 kHz), including high-tone bone conduction (1, 2, 4 kHz), air-bone gap, and speech discrimination scores. Hearing outcomes were measured: short-term (3 weeks) and long-term (average, 22 months). RESULTS: Among 17 ears undergoing revision stapedectomy managed with TOP reconstruction, the average number of previous revision attempts was 1.0 (SD, 1; range, 1-5). The preoperative bone conduction PTA was 30.7 dB preoperatively, while the preoperative air conduction PTA was 64.3 dB. The mean postoperative air-bone gap significantly decreased to 18.9 dB (SD, 12.7; range, 5-46.25; P < .003) with a mean follow-up of 22.2 months (SD, 25.0; range, 0.75-78). No significant decrement in high-tone bone conduction PTA was observed (mean, 0 dB; SD, 12.8; range, -36.7 to 20; P = .427); however, 1 ear revealed a severe decrease in PTA and speech discrimination score postoperatively. No further revisions were noted in follow-up. CONCLUSION: TOP reconstruction in the setting of previous revision stapedectomy with limited incudovestibular reconstructive options may lead to favorable hearing outcomes, but it carries an increased risk of sensorineural hearing loss.

Retained dental needle migration across the skull base to the cochlea presenting as hearing loss.

OBJECTIVES: Long-term retained foreign bodies in the human body have been reported across many specialties, but relatively few exist in the ENT literature. PATIENTS: We present a case report of a patient with a broken dental needle fragment in the posterior oral cavity with subsequent migration to the cochlea over the course of 4 years, eventually leading to hearing loss. CT scan and middle ear exploration demonstrated a 4-cm metallic fragment abutting the base of the cochlea, immediately adjacent to the internal carotid artery. INTERVENTIONS: The needle segment was removed through an endaural approach without complication. RESULTS: Postoperatively, the patient had improvements in PTA and speech discrimination, as well as the resolution of chronic otalgia and jaw pain. Imaging, audiologic results, and surgical details and pictures are presented herein. CONCLUSION: To our knowledge, based on a thorough PubMed and Google Scholar search, there are no reports of such a foreign body migration from the oral cavity to the skull base.

Vibromechanical assessment of active middle ear implant stimulation in simulated middle ear effusion: a temporal bone study.

HYPOTHESIS: Active middle ear implant (AMEI) generated vibromechanical stimulation of the ossicular chain (ossicular chain vibroplasty [OCV]) or the round window (round window vibroplasty [RWV]) is not significantly affected by simulated middle ear effusion in a human temporal bone model. BACKGROUND: OCV and RWV may be employed for sensorineural, mixed, and conductive hearing losses. Although middle ear effusions may be encountered across patient populations, little is known about how effusions may affect AMEI vibromechanical efficiency. METHODS: Laser Doppler vibrometry of stapes velocities (SVs) were performed in a human temporal bone model of simulated effusion (N = 5). Baseline measurements to acoustic sinusoidal stimuli, OCV, and RWV (0.25-8 kHz) were made without effusion. The measurements were repeated with simulated middle ear effusion and compared with baseline measurements. Data were analyzed across 3 frequency bands: low (0.25-1 kHz), medium (1-3 kHz), and high (3-8 kHz). RESULTS: Acoustic stimulation with simulated middle ear effusion resulted in a significant (p < 0.001) frequency-dependent attenuation of SVs of 4, 10, and 7 dB (low, medium, and high ranges, respectively). OCV in simulated effusion resulted in attenuated SVs of 1, 5, and 14 dB (low, medium, and high) compared to without effusion; however, this attenuation was not significant (p = 0.07). Interestingly, in the setting of RWV, simulated effusion resulted in significantly (p = 0.001) increased SVs of 16, 11, and 8 dB (low, medium, and high). A 3-dB variance in AMEI efficiency was observed in repeated measurements in a single temporal bone. CONCLUSION: The efficiency of OCV was not significantly affected by the presence of a middle ear effusion. Improved efficiency, however, was observed with RWV.

Management of incus necrosis in revision stapedectomy using hydroxyapatite bone cement.

OBJECTIVE: Review audiological outcomes after revision stapedectomy using hydroxyapatite cement. STUDY DESIGN: Retrospective case review. SETTING: Tertiary neurotological referral center. PATIENTS: Thirty-seven cases of previously treated otosclerosis where incus erosion was observed during revision stapedectomy. INTERVENTION(S): Hydroxyapatite cement was used to rebuild the eroded incus and stabilize the prosthesis during revision stapedectomy. MAIN OUTCOME MEASURE(S): Pre- and postoperative bone conduction (BC) and air conduction (AC) pure-tone averages (PTA) (0.5, 1, 2, 3 kHz) including high tone BC (1, 2, 4 kHz), air-bone gap (ABG), and speech discrimination scores were measured. Short-term (3 wk) and longer-term (average 12 mo) hearing outcomes were measured. Data are reported according to the most recent guidelines of the AAO-HNS Committee on Hearing and Equilibrium. RESULTS: Among 37 ears undergoing revision stapedectomy with hydroxyapatite cement, the AC PTA was 59.8 dB preoperatively and 34.6 dB postoperatively (p < 0.0001) at latest follow-up. The mean postoperative ABG was 8.8 dB (SD = 8.6, range -1.3-36.3 dB) while a mean improvement of 2.1 dB (SD = 6.5, range -8.33-15.0 dB) of the high tone BC PTA was observed. One revision case was noted during the follow-up period. CONCLUSION: Hydroxyapatite cement is useful to reconstruct and stabilize the prosthesis in revision stapedectomy when erosion of the long process is encountered. Short- and longer-term hearing results are favorable when compared to previously reported results of revision stapedectomy.

The conductive hearing loss due to an experimentally induced middle ear effusion alters the interaural level and time difference cues to sound location.

Otitis media with effusion (OME) is a pathologic condition of the middle ear that leads to a mild to moderate conductive hearing loss as a result of fluid in the middle ear. Recurring OME in children during the first few years of life has been shown to be associated with poor detection and recognition of sounds in noisy environments, hypothesized to result due to altered sound localization cues. To explore this hypothesis, we simulated a middle ear effusion by filling the middle ear space of chinchillas with different viscosities and volumes of silicone oil to simulate varying degrees of OME. While the effects of middle ear effusions on the interaural level difference (ILD) cue to location are known, little is known about whether and how middle ear effusions affect interaural time differences (ITDs). Cochlear microphonic amplitudes and phases were measured in response to sounds delivered from several locations in azimuth before and after filling the middle ear with fluid. Significant attenuations (20-40 dB) of sound were observed when the middle ear was filled with at least 1.0 ml of fluid with a viscosity of 3.5 Poise (P) or greater. As expected, ILDs were altered by ~30 dB. Additionally, ITDs were shifted by ~600 µs for low frequency stimuli (<4 kHz) due to a delay in the transmission of sound to the inner ear. The data show that in an experimental model of OME, ILDs and ITDs are shifted in the spatial direction of the ear without the experimental effusion.

Third-window vibroplasty with an active middle ear implant: assessment of physiologic responses in a model of stapes fixation in Chinchilla lanigera.

HYPOTHESIS: Mechanical stimulation through a cochlear third window into the scala tympani in a chinchilla model with normal and fixed stapes can generate cochlear responses equivalent to acoustic stimuli. BACKGROUND: Cochlear stimulation via the round window (RW) using active middle ear implants (AMEIs) can produce physiologic responses similar to acoustic stimulation including in a model of stapes fixation. However, pathologic conditions, such as advanced otosclerosis, can preclude delivery of sound energy to the cochlea through the oval window and/or the RW. METHODS: Cochlear microphonic (CM) and laser Doppler vibrometer measurements of stapes and RW velocities were performed in 6 ears of 4 chinchillas. Baseline measurements to acoustic sinusoidal stimuli (0.25-8 kHz) were made. Measurements were repeated with an AMEI driving the RW or a third window to the scala tympani before and after stapes fixation. RESULTS: AMEI stimulation of the third window produced CM waveforms with morphologies similar to acoustic stimuli. CM thresholds with RW and third-window stimulation were frequency dependent but ranged from 0.25 to 10 and 0.5 to 40 mV, respectively. Stapes fixation, confirmed by laser Doppler vibrometer measurements, resulted in a significant frequency dependent impairment in CM thresholds up to 13 dB (at <3 kHz) for RW stimulation and a nonsignificant frequency-dependent improvement of up to 10 dB (at >3 kHz) via third-window stimulation. CONCLUSION: AMEI mechanical stimulation through a third window into the scala tympani produces physiologic responses nearly identical to acoustic stimulation including in a model of stapes fixation with decreased efficiency.

Sound pressure transformations by the head and pinnae of the adult Chinchilla (Chinchilla lanigera).

There are three main cues to sound location: the interaural differences in time (ITD) and level (ILD) as well as the monaural spectral shape cues. These cues are generated by the spatial- and frequency-dependent filtering of propagating sound waves by the head and external ears. Although the chinchilla has been used for decades to study the anatomy, physiology, and psychophysics of audition, including binaural and spatial hearing, little is actually known about the sound pressure transformations by the head and pinnae and the resulting sound localization cues available to them. Here, we measured the directional transfer functions (DTFs), the directional components of the head-related transfer functions, for 9 adult chinchillas. The resulting localization cues were computed from the DTFs. In the frontal hemisphere, spectral notch cues were present for frequencies from ∼6-18 kHz. In general, the frequency corresponding to the notch increased with increases in source elevation as well as in azimuth towards the ipsilateral ear. The ILDs demonstrated a strong correlation with source azimuth and frequency. The maximum ILDs were <10 dB for frequencies <5 kHz, and ranged from 10-30 dB for the frequencies >5 kHz. The maximum ITDs were dependent on frequency, yielding 236 µs at 4 kHz and 336 µs at 250 Hz. Removal of the pinnae eliminated the spectral notch cues, reduced the acoustic gain and the ILDs, altered the acoustic axis, and reduced the ITDs.

Physiological assessment of active middle ear implant coupling to the round window in Chinchilla lanigera.

OBJECTIVE: To study the effects of various active middle ear implant loading parameters on round window stimulation in an animal model. STUDY DESIGN: Physiological measurements of the cochlear microphonic and stapes velocity were made from active middle ear implant-generated sinusoidal stimuli with controlled changes in loading parameters. SETTING: Prospective study at an academic research institution. SUBJECTS AND METHODS: Cochlear microphonic and stapes velocities (H(EV)) were measured in 6 study subjects (Chinchilla lanigera) in response to active middle ear implant (Otologics MET, Boulder, Colorado) round window stimulation with assessment of effects of varying parameters of loading pressure, interposed connective tissue, and angle of stimulation with respect to the round window membrane. RESULTS: The measured performance variabilities in repeated applications of the active middle ear implant to the round window were 2.5 dB and 5.0 dB for H(EV) and cochlear microphonic thresholds, respectively. Loading pressure applied to the round window (51-574 dynes) and angle of approach (±30° with respect to coronal plane) did not have a significant effect on cochlear microphonic thresholds or H(EV). Significant improvements in cochlear microphonic thresholds and H(EV) were observed for interposed connective tissue regardless of tissue type. CONCLUSION: Variability in performance due to repeated couplings of the active middle ear implant to the round window is small and reproducible. Interposition of connective tissue significantly improves vibration energy transfer to the cochlea. Neither changes in loading pressure nor angle of stimulation of the round window affected active middle ear implant performance.

Electrocochleographic and mechanical assessment of round window stimulation with an active middle ear prosthesis.

Mechanical stimulation of the round window (RW) with an active middle ear prosthesis (AMEP) has shown functional benefit in clinical reports in patients with mixed hearing loss (MHL). Further objective physiological data on the efficacy of RW stimulation is needed, however, to demonstrate that RW stimulation with an AMEP can generate input to the inner ear comparable to acoustic input. Cochlear microphonic (CM) and mechanical (stapes velocity) responses to sinusoidal stimuli were measured by electrode and laser Doppler vibrometry in eight chinchillas in response to normal acoustic stimulation via sealed calibrated insert earphones and to AMEP stimulation (Otologics MET, Boulder, CO, USA) of the RW with and without lateral ossicular chain disarticulation. CM thresholds for acoustic stimulation were frequency dependent and ranged from 16 to 50 dB SPL. CM thresholds measured with RW stimulation ranged from -14 to 35 dBmV with an intact middle ear chain and from -7 to 36 dBmV after lateral ossicular chain disarticulation. Acoustically, stapes velocity maxima was observed at approximately 700 Hz and minima at approximately 2.65 kHz. With application of the AMEP to the RW, peak stapes velocity was observed at 2-3 kHz. The equivalent ear canal sound pressure level (L(E)(max)dB SPL) evoked by RW stimulation with the AMEP was 60-105 dB SPL for the intact middle ear and 70-100 dB SPL after ossicular chain disarticulation. Stimulating the inner ear through the RW with an AMEP produces evoked responses (CM) comparable to normal acoustic input. When adjusted for threshold (due to unit differences, dB SPL or dB mV), the sensitivity of the CM (slope) for acoustic was comparable to sensitivities obtained by AMEP stimulation of the RW. Mechanical stimulation of the RW with an AMEP produces cochlear responses (CMs) and stapes velocities that are functionally equivalent to acoustic stimulation.

Prospective electrophysiologic findings of round window stimulation in a model of experimentally induced stapes fixation.

HYPOTHESIS: Mechanical stimulation of the round window (RW) with an active middle ear implant (AMEI) with and without experimentally induced stapes fixation (SF) results in equivalent electrophysiologic measures of cochlear microphonic (CM), compound action potential (CAP), and auditory brainstem response (ABR). BACKGROUND: Where normal oval window functionality is mitigated, the RW provides a pathway to mechanically stimulate the inner ear. METHODS: Measurements of the CM, CAP, and ABR were made in 5 ears of 4 chinchillas with acoustic stimulation and with application of the AMEI to the RW with and without experimentally induced SF using pure-tone stimuli (0.25-20 kHz) presented at differing intensities (-20 to 80 dB SPL vs. 0.01 mV to 3.16 V). RESULTS: Morphologies of the CM, CAP, and ABR were similar between acoustic and RW stimulation with and without SF. Stapes fixation increased CM thresholds relative to RW stimulation without fixation by a frequency-dependent 4- to 13-dB mV (mean, 7.9 +/- 3.2 dB mV). Although the thresholds changed with SF, CM sensitivities and amplitude dynamic range were identical to normal. The CAP in all conditions demonstrated equivalent decreasing amplitudes and increasing latency with decreasing intensity (decibel sound pressure level versus decibel millivolt). Stapes fixation increased the CAP thresholds at all frequencies, ranging from 9 to 24 dB mV (mean, 17.7 +/- 4.9 dB mV). Auditory brainstem response waveforms were preserved across experimental conditions. CONCLUSION: Mechanical stimulation of the RW in an animal model of SF generates functionally similar inputs to the cochlea as normal acoustic and RW mechanical inputs but with increased thresholds. With further study, AMEIs may provide a surgical option for correction of otosclerosis and ossicular chain disruption.