Margaret T. Dillon

Influence of cochlear implant insertion depth on performance: a prospective randomized trial.

Objective The purpose of the present study was to assess the influence of electrode insertion length on cochlear implant (CI) performance. Study Design Prospective randomized allocation of CI patients to receive either a standard (26.4 mm)- or medium (20.9 mm)-length electrode array. The processing strategy and electrode insertion number were held constant. The postoperative testing audiologist was blinded to the map details and array. Setting Tertiary referral center. Patients Thirteen adult CI candidates randomized to receive the standard- (n = 7) or medium-length (n = 6) electrode array. Intervention(s) Unilateral CI using standard- or medium-length array from the same implant system. Main Outcome Measures(s) Speech perception was assessed with HINT sentences in quiet and steady-state noise (SNR, +10) and CNC words in quiet at defined intervals. Quality of life was assessed using the Hearing Device Satisfaction Survey and the Abbreviated Profile of Hearing Aid Benefit (APHAB). Music perception was assessed using the Musical Sounds In Cochlear implants (MuSIC) test. Postoperative electrode insertion angle was assessed using reconstructed computed tomographic images. Results Interim analysis necessitated discontinuation of subject enrollment by the institutional review board. There was a trend (p = 0.07) for improved speech perception performance among standard array patients. This difference was significant when the standard array group was increased retrospectively. Quality of life and music perception differences were not apparent between groups. Conclusion Longer electrode insertions (and greater insertion angles) appear to offer better speech perception performance in the early postactivation period when using the same implant system.

Intraoperative round window recordings to acoustic stimuli from cochlear implant patients.

Hypothesis Acoustically evoked neural and hair cell potentials can be measured from the round window (RW) intraoperatively in the general population of cochlear implant recipients. Background Cochlear implant performance varies greatly among patients. Improved methods to assess and monitor functional hair cell and neural substrate before and during implantation could potentially aid in enhanced nontraumatic intracochlear electrode placement and subsequent improved outcomes. Methods Subjects (1–80 yr) undergoing cochlear implantation were included. A monopolar probe was placed at the RW after surgical access was obtained. The cochlear microphonic (CM), summating potential (SP), compound action potential (CAP), and auditory nerve neurophonic (ANN) were recorded in response to tone bursts at frequencies of 0.25 to 4 kHz at various levels. Results Measurable hair cell/neural potentials were detected to 1 or more frequencies in 23 of 25 subjects. The greatest proportion and magnitude of cochlear responses were to low frequencies (<1,000 Hz). At these low frequencies, the ANN, when present, contributed to the ongoing response at the stimulus frequency. In many subjects, the ANN was small or absent, whereas hair cell responses remained. Conclusion In cochlear implant recipients, acoustically evoked cochlear potentials are detectable even if hearing is extremely limited. Sensitive measures of cochlear and neural status can characterize the state of hair cell and neural function before implantation. Whether this information correlates with speech performance outcomes or can help in tailoring electrode type, placement or audiometric fitting, can be determined in future studies.

Hearing preservation and speech perception outcomes with electric‐acoustic stimulation after 12 months of listening experience

To report on single‐center data of an FDA‐approved clinical trial on the objective benefits of cochlear implantation and subsequent ipsilateral Electric‐Acoustic Stimulation (EAS).

Cochleostomy Versus Round Window Insertions: Influence on Functional Outcomes in Electric-acoustic Stimulation of the Auditory System

Objective To assess the potential influence of 2 different surgical access routes to scala tympani for hearing preservation cochlear implantation on outcomes. Study Design Retrospective review. Setting Tertiary care academic center. Patients Twenty adult subjects participating in a prospective clinical trial on electric-acoustic stimulation. Subjects underwent cochlear implantation with attempted hearing preservation and subsequent ipsilateral electric-acoustic stimulation of the auditory system. Interventions Eight subjects (40%) were implanted using a round window–related cochleostomy and 12 subjects (60%) via a round window approach. Main Outcome Measures Postoperative acoustic hearing preservation and speech perception measures were obtained at defined intervals and compared for both groups with and without the use of the external speech processor. Results The data demonstrate no statistically significant differences in postoperative outcomes for both preservation of residual hearing and unaided and aided speech perception between the cochleostomy and round window groups. Conclusion The results of this investigation suggest that hearing preservation cochlear implantation can be performed either via a round window–related cochleostomy as well as via the round window membrane itself with similar outcomes in terms of both hearing preservation rates as well as speech perception measures.

Cochlear Implant Programming: A Global Survey on the State of the Art

The programming of CIs is essential for good performance. However, no Good Clinical Practice guidelines exist. This paper reports on the results of an inventory of the current practice worldwide. A questionnaire was distributed to 47 CI centers. They follow 47600 recipients in 17 countries and 5 continents. The results were discussed during a debate. Sixty-two percent of the results were verified through individual interviews during the following months. Most centers (72%) participated in a cross-sectional study logging 5 consecutive fitting sessions in 5 different recipients. Data indicate that general practice starts with a single switch-on session, followed by three monthly sessions, three quarterly sessions, and then annual sessions, all containing one hour of programming and testing. The main focus lies on setting maximum and, to a lesser extent, minimum current levels per electrode. These levels are often determined on a few electrodes and then extrapolated. They are mainly based on subjective loudness perception by the CI user and, to a lesser extent, on pure tone and speech audiometry. Objective measures play a small role as indication of the global MAP profile. Other MAP parameters are rarely modified. Measurable targets are only defined for pure tone audiometry. Huge variation exists between centers on all aspects of the fitting practice.

Long-term Speech Perception in Elderly Cochlear Implant Users

IMPORTANCE A review of a test battery presented in both quiet and noise may clarify what the progression of speech perception abilities is in older adult cochlear implant users and whether the performance declines with advancing age. OBJECTIVE To examine whether older adults (≥65 years) with cochlear implants maintain stable speech perception performance after at least 10 years of listening experience with an external speech processor. DESIGN AND SETTING Retrospective analysis performed in an academic tertiary care center. PARTICIPANTS Fourteen older adult cochlear implant recipients with at least 10 years of listening experience. MAIN OUTCOME MEASURES Speech perception outcomes as measured with Consonant-Nucleus-Consonant words in quiet and Hearing in Noise Test sentences in quiet and steady-state noise were analyzed retrospectively at the 6-month and 1-, 5-, and 10-year postoperative follow-up intervals. RESULTS Consonant-Nucleus-Consonant word scores remained stable between 6 months and 1 year of listening experience, improved significantly (P < .001) between 1 year and 5 years, and remained stable between 5 years and 10 years. Hearing in Noise Test sentence scores in quiet and noise showed a similar pattern, with stability in performance between the 6-month to 1-year and 5-year to 10-year follow-up intervals, and significantly improved performance (P = .04) between the 1-year and 5-year follow-up intervals. CONCLUSIONS AND RELEVANCE On average, patients who undergo cochlear implantation at age 65 years or older do not experience a decline in speech perception performance with extended listening experience and may potentially continue to see improvements beyond the 1-year follow-up interval.

Round window electrocochleography and speech perception outcomes in adult cochlear implant subjects: Comparison with audiometric and biographical information

Hypothesis Intraoperative round window (RW) electrocochleography (ECoG) can help predict speech perception outcomes in adult cochlear implant (CI) recipients. Background Speech perception outcomes using CIs are highly variable. Recent data demonstrated that intraoperative ECoG could account for nearly half the variance in postoperative word scores. The present study seeks to update this correlation with a larger sample size and determine if addition of clinical variables improves the prediction. Methods Intraoperative RW ECoG was performed in adult subjects undergoing CI. Amplitudes of the ongoing response to tone bursts of multiple frequencies at 85 to 95 dB HL were summed to obtain the total response (ECoG-TR). ECoG-TR was correlated with postoperative speech perception scores. Multiple linear regression was used to combine clinical factors with the ECoG-TR. Results The ECoG-TR accounted for 40% of the variance in CNC word scores (n = 32). The preoperative pure tone average (PTA) was the only clinical factor with a significant correlation (r2 = 20%). The ability to predict word scores using ECoG-TR and PTA, or after addition of age and duration of hearing loss, was not significantly different from using ECoG-TR alone. For 2 outliers, ECoG-TR predicted a better word score than obtained. Conclusions The measurement of cochlear physiology before CI, reduced to a single variable, is a better predictor of postoperative speech perception than common clinical factors. Additional analysis of the outliers showed that waveform morphology can provide distinct information in individual cases.

Cochlear Implantation in Cases of Unilateral Hearing Loss: Initial Localization Abilities

Objectives: The present study evaluated early auditory localization abilities of cochlear implant (CI) recipients with normal or near-normal hearing (NH) in the contralateral ear. The goal of the study was to better understand the effect of CI listening experience on localization in this population. Design: Twenty participants with unilateral hearing loss enrolled in a prospective clinical trial assessing outcomes of cochlear implantation (ClinicalTrials.gov Identifier: NCT02203305). All participants received the MED-EL Standard electrode array, were fit with an ear-level audio processor, and listened with the FS4 coding strategy. Localization was assessed in the sound field using an 11-speaker array with speakers uniformly positioned on a horizontal, semicircular frame. Stimuli were 200-msec speech-shaped noise bursts. The intensity level (52, 62, and 72 dB SPL) and sound source were randomly interleaved across trials. Participants were tested preoperatively, and 1, 3, and 6 months after activation of the audio processor. Performance was evaluated in two conditions at each interval: (1) unaided (NH ear alone [NH-alone] condition), and (2) aided, with either a bone conduction hearing aid (preoperative interval; bone conduction hearing aid + NH condition) or a CI (postoperative intervals; CI + NH condition). Performance was evaluated by comparing root-mean-squared (RMS) error between listening conditions and between measurement intervals. Results: Mean RMS error for the soft, medium, and loud levels were 66°, 64°, and 69° in the NH-alone condition and 72°, 66°, and 70° in the bone conduction hearing aid + NH condition. Participants experienced a significant improvement in localization in the CI + NH condition at the 1-month interval (38°, 35°, and 38°) as compared with the preoperative NH-alone condition. Localization in the CI + NH condition continued to improve through the 6-month interval. Mean RMS errors were 28°, 25°, and 28° in the CI + NH condition at the 6-month interval. Conclusions: Adult CI recipients with normal or near-normal hearing in the contralateral ear experienced significant improvement in localization after 1 month of device use, and continued to improve through the 6-month interval. The present results show that binaural acclimatization in CI users with unilateral hearing loss can progress rapidly, with marked improvements in performance observed after only 1 month of listening experience.

The Compound Action Potential in Subjects Receiving a Cochlear Implant.

Hypothesis: The compound action potential (CAP) is a purely neural component of the cochleas response to sound, and may provide information regarding the existing neural substrate in cochlear implant (CI) subjects that can help account for variance in speech perception outcomes. Background: Measurement of the “total response” (TR), or sum of the magnitudes of spectral components in the ongoing responses to tone bursts across frequencies, has been shown to account for 40 to 50% of variance in speech perception outcomes. The ongoing response is composed of both hair cell and neural components. This correlation may be improved with the addition of the CAP. Methods: Intraoperative round window electrocochleography (ECochG) was performed in adult and pediatric CI subjects (n = 238). Stimuli were tones of different frequencies (250 Hz–4 kHz) at 90 dB nHL. The CAP was assessed in two ways, as an amplitude and with a scaling factor derived from a function fitted to the response. The results were correlated with consonant-nucleus-consonant (CNC) word scores at 6 months post-implantation (n = 51). Results: Only about half of the subjects had a measurable CAP at any frequency. The CNC word scores correlated weakly with both amplitude (r2 = 0.20, p < 0.001) and scaling factor (r2 = 0.25, p < 0.01). In contrast, the TR alone accounted for 43% of the variance, and addition of either CAP measurement in multiple regression did not account for additional variance. Conclusions: The underlying pathology in CI patients causes the CAP to be often absent and highly variable when present. The TR is a better predictor of speech perception outcomes than the CAP.

Influence of Age at Revision Cochlear Implantation on Speech Perception Outcomes

IMPORTANCE This study reviewed whether advanced age should be a consideration when revision cochlear implantation is warranted. OBJECTIVE To examine whether age at revision cochlear implantation is related to postrevision speech perception performance. DESIGN, SETTING, AND PARTICIPANTS A retrospective analysis was performed in an academic tertiary care center. Participants included 14 younger adults (<65 years) and 15 older adults (≥65 years) who underwent revision cochlear implantation. INTERVENTION Revision cochlear implantation. MAIN OUTCOMES AND MEASURES Speech perception performance, as measured with consonant-nucleus-consonant [CNC] words in quiet, at the best prerevision interval as well as the 3- and 6-month postrevision intervals were compared between the 2 cohorts. The CNC word test consists of 10 lists of 50 phonemically balanced monosyllabic words, scored with a range of 0% to 100% correct. RESULTS Both cohorts experienced a restoration in speech perception scores after revision cochlear implantation compared with their best performance before the revision (mean [SD] CNC word test scores for the younger cohort: 43.9% [25.6%] before revision and 47.7% [21.3%] at 3 months and 47.6% [19.8%] at 6 months after revision; for the older cohort: 36.3% [19.1%] before revision and 35.3% [17.2%] at 3 months and 39.9% [16.3%] at 6 months after revision; F₂,₅₄= 0.93; P = .40). There was no interaction between age at revision surgery and speech perception performance at each assessment interval (F₂,₅₄= 0.51; P = .60). CONCLUSIONS AND RELEVANCE In this study, age at revision cochlear implantation was not related to postrevision speech perception performance. Advanced age should not be considered a contraindication to revision cochlear implantation.