The Role of Preoperative Steroids for Hearing Preservation Cochlear Implantation: Results of a Randomized Controlled Trial.

OBJECTIVES: To determine whether preoperative steroids can improve hearing outcomes in cochlear implantation (CI). METHODS: This is a randomized controlled trial involving 30 postlingual deaf CI patients. Subjects had preoperative thresholds of better than or equal to 80 dB at 125 and 250 Hz, and better than or equal to 90 dB at 500 and 1,000 Hz. The subjects were randomized to a control group, an oral steroid group (receiving 1 mg/kg/day of prednisolone for 6 days prior to surgery), or a transtympanic steroid group (receiving a single dose of 0.5 mL of 10 mg/mL dexamethasone at 24 h prior to surgery). RESULTS: The subjects receiving transtympanic steroids had a significant decrease in the pure tone average over 3 months compared to the control and oral steroid group, which persisted over 12 months (p < 0.05). CONCLUSION: A single dose of preoperative transtympanic steroids prior to CI appears to have a beneficial effect, at least in the short term, with minimal effects seen in the longer term.

A novel method for extraction of neural response from single channel cochlear implant auditory evoked potentials.

Cortical auditory evoked potentials (CAEP) are used to evaluate cochlear implant (CI) patient auditory pathways, but the CI device produces an electrical artifact, which obscures the relevant information in the neural response. Currently there are multiple methods, which attempt to recover the neural response from the contaminated CAEP, but there is no gold standard, which can quantitatively confirm the effectiveness of these methods. To address this crucial shortcoming, we develop a wavelet-based method to quantify the amount of artifact energy in the neural response. In addition, a novel technique for extracting the neural response from single channel CAEPs is proposed. The new method uses matching pursuit (MP) based feature extraction to represent the contaminated CAEP in a feature space, and support vector machines (SVM) to classify the components as normal hearing (NH) or artifact. The NH components are combined to recover the neural response without artifact energy, as verified using the evaluation tool. Although it needs some further evaluation, this approach is a promising method of electrical artifact removal from CAEPs.

The role of a new contralateral routing of signal microphone in established unilateral cochlear implant recipients.

OBJECTIVES/HYPOTHESIS: To investigate whether a contralateral routing of signal (CROS) microphone combined with a unilateral cochlear implant (CI) results in hearing improvement after a prolonged trial period. STUDY DESIGN: A prospective experimental trial was undertaken on a group of 10 postlingually deafened adults who are experienced CI users. METHODS: Participants completed audiometric testing and validated questionnaires with their unilateral CI alone, followed by addition of a CROS microphone (CI-CROS). This was worn daily for the 2-week trial, after which hearing performance was reevaluated using the same measures. Objective tests included AzBio sentences in quiet and noise and consonant-vowel nucleus-consonant (CNC) words. Subjective measures included the Abbreviated Profile of Hearing Aid Benefit (APHAB); Speech, Spatial, Qualities of Hearing Index (SSQ); Hearing Implant Sound Quality Index; an institutional questionnaire; and a daily log sheet. RESULTS: There is statistically significant enhanced speech discrimination with the CI-CROS when speech is presented on the CROS side. However, scores are markedly diminished when background noise is introduced, particularly to the CROS side. Subjective results indicate lower satisfaction scores for the global and ease of communication subdomains of the APHAB with the CI-CROS, but increased scores on the spatial hearing subdomain of the SSQ (P < 0.05). CONCLUSION: The CI-CROS provides significant benefit in certain situations, particularly speech recognition in quiet. CI-CROS performance with background noise is poor, leading to low satisfaction scores. Further refinement of the device may yield a useful tool for unilateral CI users in the future.

Analysis of cochlear implant artifact removal techniques using the continuous wavelet transform.

When patients with cochlear implants (CI) undergo cortical auditory evoked potential (CAEP) tests to evaluate their hearing, a large electrical artifact introduced by the CI obscures the relevant information in the signal. Several methods have been developed for the purpose of removing the CI artifact; however, there is no gold standard (i.e., patient's auditory response before the CI) to assess the effectiveness of these methods in terms of successful removal of artifact. To address this crucial shortcoming, we employ time-frequency (TF) signal representation (i.e., continuous wavelet transform (CWT)) to evaluate the effectiveness of two recent CI removal techniques, known as the subtraction and polynomial methods. Our results show that polynomial method consistently outperforms the subtraction method in the presence of tone stimulus. These results also indicate a possible CWT-based method for removing the CI artifact from a speech stimuli response, which the subtraction and polynomial methods cannot do.

Cochlear implantation in patients with advanced Ménière's disease.

BACKGROUND/OBJECTIVES: Ménière's disease (MD) that results in bilateral severe to profound sensorineural hearing loss is a rare indication for cochlear implantation; only a few studies exist documenting performance in these patients. The primary objective was to compare the difference in preoperative to 12-month postoperative speech perception scores among subjects with MD and controls. Groupwise comparisons of secondary postoperative outcomes (Tinnitus Handicap Inventory [THI] scores, 36-Item Short Form [SF-36] scores, and postoperative dizziness) were also performed. METHODS: A retrospective cohort study was conducted. Subjects with MD and controls matched by age, device manufacturer and model, preoperative sentence score, and sentence test used for preimplantation and postimplantation performance assessments were identified from 1,130 patients in the prospectively maintained cochlear implant database at our center. Speech perception, THI, and SF-36 scores and demographic variables were obtained from the database. Vestibular outcomes were obtained by retrospective chart review. Statistical comparisons were performed to compare preoperative to postoperative change between groups. RESULTS: Twenty patients with MD were identified. At 1 year after CI, improvements in sentence and word understanding did not differ in magnitude from the controls. Tinnitus was reduced significantly in patients with MD, whereas there was a trend for improvement in the controls. Quality of life as measured by the SF-36 improved in both groups. Patients with MD had significant improvements in 1 domain compared with 5 domains for the controls. Subjects with MD had significantly more chronic dizziness in the postoperative period than did controls. CONCLUSIONS: Patients with MD who have bilateral severe to profound sensorineural hearing loss benefit significantly from CI. Ongoing dizziness in some patients with MD may result in quality of life improvements that are slightly less than seen for the average adult patient with CI. Larger studies are needed to corroborate the results.

Hearing preservation with full insertion of the FLEXsoft electrode.

OBJECTIVES: Hearing preservation (HP) in the context of cochlear implantation (CI) is indicative of an atraumatic insertion, which could potentially offer a clinical advantage to performance, whether such preservation was intended for the application of electoacoustic stimulation (EAS). Our goal was to determine the degree of HP after the implantation of a full-length electrode array (MedEl FLEXsoft). STUDY DESIGN: Prospective, within-subject repeated measure design. METHODS: Adult patients with residual low-frequency hearing who received a 31.5-mm FlexSoft electrode array were included. Implantation using soft surgery techniques occurred at a single tertiary referral center between 2008 and 2011. Preoperative and postoperative audiometric data were compared. RESULTS: In 36 consecutive patients at 1 year postimplantation, 6 (21%) maintained complete HP (an increase of low-frequency pure-tone average (PTA) ≤10 dB from the preoperative value), and 19 (65%) maintained partial HP (an increase in low-frequency PTA ≤40 dB from the preoperative values) throughout the follow-up period (average, 368 d). Higher preoperative hearing threshold levels (HTLs) at 1,000 Hz were associated with HP. CONCLUSION: Low-frequency HP is possible in patients implanted with the full-length FlexSoft electrode. Longer follow-up is required to determine if results are maintained over time and if such preservation is in fact advantageous to clinical outcomes. LEVEL OF EVIDENCE: 4.

The addition of a contralateral routing of signals microphone to a unilateral cochlear implant system--a prospective study in speech outcomes.

OBJECTIVES/HYPOTHESIS: The purpose of the study was to investigate the potential clinical advantages of incorporating a contralateral routing of signals (CROS) microphone in unilateral cochlear implant (CI) users. STUDY DESIGN: A prospective study was undertaken on a group of 21 postlingually deafened adults who were all implanted with the same multichannel CI system. METHODS: Performance with a unilateral CI was compared with performance using both a unilateral implant and a CROS microphone system worn on the opposite site (CI-CROS). Speech understanding using the AzBio sentence was evaluated in quiet, with speech presented at 0° and 270° azimuth in the horizontal plane. Speech understanding in noise was performed with speech at 0°, and noise at 0°, 90°, and 270°. RESULTS: A significant gain in speech understanding using CI-CROS compared to the unilateral CI alone was found in quiet when speech was presented at 270° (average improvement of 8.8%, P < .01). Participants also demonstrated statistically significant improvement using CI-CROS compared with the unilateral CI alone when noise was presented at 90° and speech at 0° (average improvement of 6.7%, P < .01). CONCLUSIONS: Adding a contralateral microphone to a unilateral CI resulted in a significant improvement in speech understanding in different conditions. This method could provide a greater cost/benefit ratio than bilateral CIs and be a potential improvement for those who are not candidates for bilateral CIs.

Unilateral multi-channel cochlear implantation results in significant improvement in quality of life.

OBJECTIVES: To investigate the effects of unilateral multi-channel cochlear implant surgery on health-related quality of life and to determine if there is an age-related impact of cochlear implantation on these effects. DESIGN: Prospective study. SETTING: Tertiary health-care center. METHODS: The Short Form-36 survey (SF-36) was administered to determine the health-related quality of life of 283 age-stratified patients before and after cochlear implant surgery. MAIN OUTCOMES: Precochlear to postcochlear implantation changes in health-related quality of life as determined by the SF-36 questionnaire. RESULTS: There were significant increases in precochlear and postcochlear implantation scores for 5 of the 8 SF-36 survey domains: vitality, physical role functioning, mental health, emotional role functioning, and social functioning. Significant differences were found between age groups in the domains of social functioning, emotion role functioning, and mental health. CONCLUSION: Cochlear implant surgery significantly improves health-related quality of life as categorically stratified by the SF-36 questionnaire. These improvements were most evident in the mental health, emotional and social functioning, and physical functioning at work questions of the survey. Cochlear implant recipients younger than 65 years perceive a greater improvement in their level of energy, mental health, and social function compared with those older than 65 years.

Results with cochlear implantation in adults with speech recognition scores exceeding current criteria.

OBJECTIVES: The primary purpose of this study was to evaluate a group of postlingually deafened adults, whose aided speech recognition exceeded commonly accepted candidacy criteria for implantation. The study aimed to define performance and qualitative outcomes of cochlear implants in these individuals compared with their optimally fitted hearing aid(s). STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: All postlingually deafened subjects (N = 27), who were unsuccessful hearing aid users implanted between 2000 and 2010 with a preimplantation Hearing in Noise Test (HINT) score of 60% or more were included. INTERVENTION: We compared patients' preoperative performance (HINT score) with hearing aids to postoperative performance with the cochlear implant after 12 months of device use. In addition, the Hearing Handicap Inventory questionnaire was used to quantify the hearing-related handicap change perceived after the implantation. RESULTS: The study group demonstrated significant postoperative improvement on all outcome measures; most notably, the mean HINT score improved from 68.4% (standard deviation, 8.3) to 91.9% (standard deviation, 9.7). Additionally, there was a significant improvement in hearing-related handicap perceived by all patients. CONCLUSION: The envelope of implantation candidacy criteria continues to expand as shown by this study's cohort. Patient satisfaction and speech recognition results are very encouraging in support of treating those who currently perform at a level above the conventional candidacy threshold but struggle with optimally fitted hearing aids.

From fragments to the whole: a comparison between cochlear implant users and normal-hearing listeners in music perception and enjoyment.

BACKGROUND: Cochlear implants (CIs) allow many profoundly deaf individuals to regain speech understanding. However, the ability to understand speech does not necessarily guarantee music enjoyment. Enabling a CI user to recover the ability to perceive and enjoy the complexity of music remains a challenge determined by many factors. OBJECTIVES: (1) To construct a novel, attention-based, diagnostic software tool (Music EAR) for the assessment of music enjoyment and perception and (2) to compare the results among three listener groups. METHODS: Thirty-six subjects completed the Music EAR assessment tool: 12 normal-hearing musicians (NHMs), 12 normal-hearing nonmusicians (NHnMs), and 12 CI listeners. Subjects were required to (1) rate enjoyment of musical excerpts at three complexity levels; (2) differentiate five instrumental timbres; (3) recognize pitch pattern variation; and (4) identify target musical patterns embedded holistically in a melody. RESULTS: Enjoyment scores for CI users were comparable to those for NHMs and superior to those for NHnMs and revealed that implantees enjoyed classical music most. CI users performed significantly poorer in all categories of music perception compared to normal-hearing listeners. Overall CI user scores were lowest in those tasks requiring increased attention. Two high-performing subjects matched or outperformed NHnMs in pitch and timbre perception tasks. CONCLUSIONS: The Music EAR assessment tool provides a unique approach to the measurement of music perception and enjoyment in CI users. Together with auditory training evidence, the results provide considerable hope for further recovery of music appreciation through methodical rehabilitation.

Telephone use and the factors influencing it among cochlear implant patients.

OBJECTIVE: To investigate telephone use in cochlear implant patients and to determine factors most likely to influence telephone use. METHODS: Surveys were mailed to 504 cochlear implant patients treated at Sunnybrook Health Sciences Hospital. RESULTS: Two hundred four patients returned surveys (49%), 87% were classified as telephone users. No differences were found in age, pre-implant hearing characteristics, and the majority of post-implant behaviors. Education and post-implant sound perception scores were found to be significantly different (P < 0.05) between telephone users and non-users. DISCUSSION: Telephone use among cochlear implant patients shows a positive increase compared to previous studies. In addition, we find that higher attained education and post-implant hearing scores to be independently correlated to telephone use.

Qualitative case studies of five cochlear implant recipients' experience with music.

Cochlear implantation has revolutionized the management of those who suffer from severe-to-profound hearing loss because many patients now achieve excellent speech understanding with objective testing. Nevertheless, speech understanding in noisy conditions and music appreciation remain significant challenges to cochlear implant (CI) users. Music appreciation is an extremely complex experience that is difficult to quantify through a conventional outcome study. This paper aims at documenting the experience of five CI patients with regard to music appreciation using qualitative techniques. This information was obtained through a semi-structured interview process. The interviews were then transcribed and analysed using a constant comparative method of qualitative description. The results together with medical case records were used to identify emerging themes. The common themes that evolved were: musical background, the experience of receiving the implant, current experience with music, attention, musical prediction ability, internal hearing, hedonic vs. critical listening, determination, and timbre perception. By documenting their experiences in this manner, novel insights into the patient perspective are provided that are unique to the literature. These descriptions will aid clinicians and researchers who work in the area of cochlear implantation to better understand the needs of their patients.

The effects of unilateral cochlear implantation on the tinnitus handicap inventory and the influence on quality of life.

OBJECTIVES/HYPOTHESIS: Cochlear implantation is now the standard of care in patients with significant sensorineural hearing loss. It is well known that patients with severe hearing loss also experience disabling tinnitus. The purpose of this study was to assess the effects of cochlear implants on the perception of tinnitus using the Tinnitus Handicap Inventory (THI). STUDY DESIGN: Prospective, longitudinal study of 142 cochlear implant patients. METHODS: The THI was administered to 142 patients pre- and postimplantation. Outcome measures were obtained 12 months after the implantation. Secondary analyses to examine the correlation between changes in THI scores and outcome measures such as Hearing Handicap Inventory, Hearing in Noise Test (HINT), and short-form 36 (SF-36) quality-of-life scores were performed. RESULTS: Patients demonstrated statistically significant reduction of the THI scores including its subscales (P < .001). Prior to implantation, 37% of patients described their tinnitus as moderate to severe. Postoperatively, this percentage decreased to 10%. Cochlear implantation resulted in complete tinnitus suppression in 37% and tinnitus reduction in another 29% of patients. THI scores significantly correlated with three domains of the SF-36 quality-of-life questionnaire, namely social, emotional, and general health domains. CONCLUSIONS: Cochlear implants have a significant suppressive effect on tinnitus in 66% of implant users. Although the reduction in the subjectively perceived tinnitus was statistically significant, it did not correlate with HINT; however, it did correlate with three quality-of-life domains, more significantly for those whose pretreatment conditions were moderate or worse.

A method for removing cochlear implant artifact.

When cortical auditory evoked potentials (CAEPs) are recorded in individuals with a cochlear implant (CI), electrical artifact can make the CAEP difficult or impossible to measure. Since increasing the interstimulus interval (ISI) increases the amplitude of physiological responses without changing the artifact, subtracting CAEPs recorded with a short ISI from those recorded with a longer ISI should show the physiological response without any artifact. In the first experiment, N1-P2 responses were recorded using a speech syllable and tone, paired with ISIs that changed randomly between 0.5 and 4s. In the second experiment, the same stimuli, at ISIs of either 500 or 3000ms, were presented in blocks that were homogeneous or random with respect to the ISI or stimulus. In the third experiment, N1-P2 responses were recorded using pulse trains with 500 and 3000ms ISIs in 4 CI listeners. The results demonstrated: (1) N1-P2 response amplitudes generally increased with increasing ISI. (2) Difference waveforms were largest for the homogeneous and random-stimulus blocks than for the random-ISI block. (3) The subtraction technique almost completely eliminated the electrical artifact in individuals with cochlear implants. Therefore, the subtraction technique is a feasible method of removing from the N1-P2 response the electrical artifact generated by the cochlear implant.

Acoustic change complexes recorded in adult cochlear implant listeners.

OBJECTIVES: The objectives of this study were to determine: 1) whether the acoustic change complex (ACC) could be reliably recorded in cochlear implant listeners and, 2) whether different speech sounds evoke distinct ACC patterns. DESIGN: Eight adults wearing the Nucleus-24 cochlear implant (CI) were tested using naturally produced speech tokens /si/ and /i/. Stimuli were tokens from the standardized UCLA version of the Nonsense Syllable Test. Using a repeated-measures design, participants were tested and retested within a 3-wk period. RESULTS: Intraclass correlation coefficients for grand mean and individual-response waveforms recorded from the syllables /si/ and /i/ ranged from 0.63 to 0.89 from test to retest. Also, ACC latencies signaling the onset of a vowel in /i/ were significantly earlier than those evoked by /si/. CONCLUSIONS: The ACC can be reliably recorded in individuals wearing CI. Furthermore, the naturally produced speech syllables /si/ and /i/ evoke distinct ACC patterns. Because of its good stability and the ease with which it can be recorded in individual CI listeners, the ACC can be evoked using complex signals (such as naturally produced speech syllables) when studying central auditory function in CI listeners.

Neural representation of amplified speech sounds.

OBJECTIVE: To determine if (1) evoked potentials elicited by amplified speech sounds (/si/ and /[symbol: see text]/) can be recorded reliably in individuals, (2) amplification alters neural response patterns, and (3) different amplified speech sounds evoke different neural patterns. DESIGN: Cortical evoked potentials were recorded in sound field from seven normal-hearing young adults in response to naturally produced speech tokens /si/ and /[symbol: see text]/ from the Nonsense Syllable Test. With the use of a repeated-measures design, subjects were tested and then retested within an 8-day period in both aided and unaided conditions. RESULTS: (1) Speech-evoked cortical potentials can be recorded reliably in individuals in both aided and unaided conditions. (2) Hearing aids that provide a mild high-frequency gain only subtly enhance peak amplitudes relative to unaided cortical recordings. (3) If the consonant-vowel boundary is preserved by the hearing aid, it can also be detected neurally, resulting in different neural response patterns for /si/ and /[symbol: see text]/. CONCLUSIONS: Speech-evoked cortical potentials can be recorded reliably in individuals during hearing aid use. A better understanding of how amplification (and device settings) affects neural response patterns is still needed.

Effects of stimulation rate on speech recognition with cochlear implants.

Phoneme and speech recognition were measured as a function of stimulation pulse rate in 12 listeners with three types of cochlear implants. Identification of consonants and vowels and recognition of words and sentences were measured in 5 Clarion C1 subjects fit with continuous interleaved sampling (CIS) processors having 4 or 8 electrodes, 4 Nucleus 24 subjects fit with CIS processors having 4, 8, 12 or 16 electrodes and 3 Clarion C2 subjects fit with CIS processors with 4, 8, 12 and 16 electrodes. Stimulation rates ranged from 200 to more than 5000 Hz per electrode, depending on the device, number of electrodes used and stimulation strategy. Listeners were also tested on the same materials with their original processor prior to receiving the experimental processors. All testing was done in quiet listening conditions with essentially no practice with the experimental processor prior to data collection. Listeners scored the highest with their original processor. Little difference in speech understanding was observed for listener scores with processors using different stimulation rates. Speech recognition was significantly poorer only at the lowest stimulation rate and at high rates that used noninterleaved pulses. Speech recognition was similar for processors using 8, 12 or 16 electrodes. Only 4-electrode processors produced a significantly poorer performance. These results suggest that patients with present commercial implants are not able to make full use of the number of channels of spectral information delivered by the present speech processors. In addition, the results show no significant change in performance as a function of stimulation rate, suggesting that high stimulation rates do not result in improved access to temporal cues in speech, at least under quiet listening conditions.