1
|
Quass GL, Kral A. Tripolar configuration and pulse shape in cochlear implants reduce channel interactions in the temporal domain. Hear Res 2024; 443:108953. [PMID: 38277881 DOI: 10.1016/j.heares.2024.108953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 01/28/2024]
Abstract
The present study investigates effects of current focusing and pulse shape on threshold, dynamic range, spread of excitation and channel interaction in the time domain using cochlear implant stimulation. The study was performed on 20 adult guinea pigs using a 6-channel animal cochlear implant, recording was performed in the auditory midbrain using a multielectrode array. After determining the best frequencies for individual recording contacts with acoustic stimulation, the ear was deafened and a cochlear implant was inserted into the cochlea. The position of the implant was controlled by x-ray. Stimulation with biphasic, pseudomonophasic and monophasic stimuli was performed with monopolar, monopolar with common ground, bipolar and tripolar configuration in two sets of experiments, allowing comparison of the effects of the different stimulation strategies on threshold, dynamic range, spread of excitation and channel interaction. Channel interaction was studied in the temporal domain, where two electrodes were activated with pulse trains and phase locking to these pulse trains in the midbrain was quantified. The results documented multifactorial influences on the response properties, with significant interaction between factors. Thresholds increased with increasing current focusing, but decreased with pseudomonophasic and monophasic pulse shapes. The results documented that current focusing, particularly tripolar configuration, effectively reduces channel interaction, but that also pseudomonophasic and monophasic stimulation and phase duration intensity coding reduce channel interactions.
Collapse
Affiliation(s)
- Gunnar L Quass
- Institute for AudioNeuroTechnology (VIANNA) & Department of Experimental Otology, Otolaryngology Clinics, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4All" (EXC 2177), Germany.
| | - Andrej Kral
- Institute for AudioNeuroTechnology (VIANNA) & Department of Experimental Otology, Otolaryngology Clinics, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4All" (EXC 2177), Germany; Australian Hearing Hub, School of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| |
Collapse
|
2
|
Variations in microanatomy of the human modiolus require individualized cochlear implantation. Sci Rep 2022; 12:5047. [PMID: 35322066 PMCID: PMC8943032 DOI: 10.1038/s41598-022-08731-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 03/10/2022] [Indexed: 11/09/2022] Open
Abstract
Cochlear variability is of key importance for the clinical use of cochlear implants, the most successful neuroprosthetic device that is surgically placed into the cochlear scala tympani. Despite extensive literature on human cochlear variability, few information is available on the variability of the modiolar wall. In the present study, we analyzed 108 corrosion casts, 95 clinical cone beam computer tomographies (CTs) and 15 µCTs of human cochleae and observed modiolar variability of similar and larger extent than the lateral wall variability. Lateral wall measures correlated with modiolar wall measures significantly. ~ 49% of the variability had a common cause. Based on these data we developed a model of the modiolar wall variations and related the model to the design of cochlear implants aimed for perimodiolar locations. The data demonstrate that both the insertion limits relevant for lateral wall damage (approximate range of 4–9 mm) as well as the dimensions required for optimal perimodiolar placement of the electrode (the point of release from the straightener; approximate range of 2–5mm) are highly interindividually variable. The data demonstrate that tip fold-overs of preformed implants likely result from the morphology of the modiolus (with radius changing from base to apex), and that optimal cochlear implantation of perimodiolar arrays cannot be guaranteed without an individualized surgical technique.
Collapse
|
3
|
Stupak N, Padilla M, Morse RP, Landsberger DM. Perceptual Differences Between Low-Frequency Analog and Pulsatile Stimulation as Shown by Single- and Multidimensional Scaling. Trends Hear 2019; 22:2331216518807535. [PMID: 30378468 PMCID: PMC6236864 DOI: 10.1177/2331216518807535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Cochlear-implant users who have experienced both analog and pulsatile sound
coding strategies often have strong preferences for the sound quality of one
over the other. This suggests that analog and pulsatile stimulation may provide
different information or sound quality to an implant listener. It has been well
documented that many implant listeners both prefer and perform better with
multichannel analog than multichannel pulsatile strategies, although the reasons
for these differences remain unknown. Here, we examine the perceptual
differences between analog and pulsatile stimulation on a single electrode. A
multidimensional scaling task, analyzed across two dimensions, suggested that
pulsatile stimulation was perceived to be considerably different from analog
stimulation. Two associated tasks using single-dimensional scaling showed that
analog stimulation was perceived to be less Clean on average than pulsatile
stimulation and that the perceptual differences were not related to pitch. In a
follow-up experiment, it was determined that the perceptual differences between
analog and pulsatile stimulation were not dependent on the interpulse gap
present in pulsatile stimulation. Although the results suggest that there is a
large perceptual difference between analog and pulsatile stimulation, further
work is needed to determine the nature of these differences.
Collapse
Affiliation(s)
- Natalia Stupak
- 1 Department of Otolaryngology, New York University School of Medicine, NY, USA
| | - Monica Padilla
- 1 Department of Otolaryngology, New York University School of Medicine, NY, USA.,2 USC Tina and Rick Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Robert P Morse
- 3 School of Engineering, University of Warwick, Coventry, UK
| | - David M Landsberger
- 1 Department of Otolaryngology, New York University School of Medicine, NY, USA
| |
Collapse
|
4
|
Schwieger J, Esser KH, Lenarz T, Scheper V. Establishment of a long-term spiral ganglion neuron culture with reduced glial cell number: Effects of AraC on cell composition and neurons. J Neurosci Methods 2016; 268:106-16. [DOI: 10.1016/j.jneumeth.2016.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 01/13/2023]
|
5
|
Neuronal Survival, Morphology and Outgrowth of Spiral Ganglion Neurons Using a Defined Growth Factor Combination. PLoS One 2015; 10:e0133680. [PMID: 26263175 PMCID: PMC4532470 DOI: 10.1371/journal.pone.0133680] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/29/2015] [Indexed: 12/25/2022] Open
Abstract
Objectives The functionality of cochlear implants (CI) depends, among others, on the number and excitability of surviving spiral ganglion neurons (SGN). The spatial separation between the SGN, located in the bony axis of the inner ear, and the CI, which is inserted in the scala tympani, results in suboptimal performance of CI patients and may be decreased by attracting the SGN neurites towards the electrode contacts. Neurotrophic factors (NTFs) can support neuronal survival and neurite outgrowth. Methods Since brain-derived neurotrophic factor (BDNF) is well known for its neuroprotective effect and ciliary neurotrophic factor (CNTF) increases neurite outgrowth, we evaluated if the combination of BDNF and CNTF leads to an enhanced neuronal survival with extended neurite outgrowth. Both NTFs were added in effective high concentrations (BDNF 50ng/ml, CNTF 100ng/ml), alone and in combination, to cultured dissociated SGN of neonatal rats for 48 hours. Results The neuronal survival and neurite outgrowth were significantly higher in SGN treated with the combination of the two NTFs compared to treatment with each factor alone. Additionally, with respect to the morphology, the combination of BDNF and CNTF leads to a significantly higher number of bipolar neurons and a decreased number of neurons without neurites in culture. Conclusion The combination of BDNF and CNTF shows a great potential to increase the neuronal survival and the number of bipolar neurons in vitro and to regenerate retracted nerve fibers.
Collapse
|
6
|
Brendel M, Rottmann T, Lenarz T, Buechner A. Performance of the Harmony™ behind-the-ear processor with the first generation of Advanced Bionics™ implant systems. Cochlear Implants Int 2013; 14:36-44. [PMID: 23340091 DOI: 10.1179/1754762811y.0000000032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES When new cochlear implant (CI) sound processors are being introduced by the manufacturers, usually the newest generation implants benefit first from the new technology in order to release the full potential of the new hardware. Subsequently, for the Advanced Bionics system the Harmony behind-the-ear processor was only compatible to the newer generation implants, i.e. the CII and HiRes90K, at the time of market release. After further development of a new Digital Signal Processing code the Harmony could also support the first implant generation, the 'C1' (Clarion 1.0 and 1.2). This study reports on a field trial with a new sound processor designed to be used with older generation CIs from Advanced Bionics, focussing on ergonomic and performance benefits. METHODS Speech perception tests (Freiburger monosyllables, HSM sentence tests) were performed at a baseline appointment with the subject's clinical processor, followed by the fitting of the Harmony. After a 1 month take-home period the tests were repeated with the Harmony. Additionally, subjective evaluation through questionnaires and a structured interview were administered after upgrading to the sound processor 'C1 Harmony'. Adult users of Advanced Bionics C1 series CIs (n = 29) participated in this study. RESULTS The new processor provided superior performance in many, though not all, of the speech recognition measurements. Subjective reports indicated certain practical benefits from the new processor, particularly for previous users of body-worn processors. Overall, 80% of the subjects preferred the new processor. CONCLUSION The positive outcomes from this trial have resulted in the decision to make the new C1 Harmony processor available to all existing users of the early C1 devices.
Collapse
Affiliation(s)
- Martina Brendel
- Department of Otolaryngology, Medical University of Hannover, Hannover, Germany.
| | | | | | | |
Collapse
|
7
|
Buechner A, Frohne-Buechner C, Boyle P, Battmer RD, Lenarz T. A high rate n-of-m speech processing strategy for the first generation Clarion cochlear implant. Int J Audiol 2009; 48:868-75. [DOI: 10.3109/14992020903095783] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
8
|
Buechner A, Frohne-Buechner C, Gaertner L, Lesinski-Schiedat A, Battmer RD, Lenarz T. Evaluation of Advanced Bionics high resolution mode. Int J Audiol 2009; 45:407-16. [PMID: 16938799 DOI: 10.1080/14992020600625155] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The objective of this paper is to evaluate the advantages of the Advanced Bionic high resolution mode for speech perception, through a retrospective analysis. Forty-five adult subjects were selected who had a minimum experience of three months' standard mode (mean of 10 months) before switching to high resolution mode. Speech perception was tested in standard mode immediately before fitting with high resolution mode, and again after a maximum of six months high resolution mode usage (mean of two months). A significant improvement was found, between 11 and 17%, depending on the test material. The standard mode preference does not give any indication about the improvement when switching to high resolution. Users who are converted within any study achieve a higher performance improvement than those converted in the clinical routine. This analysis proves the significant benefits of high resolution mode for users, and also indicates the need for guidelines for individual optimization of parameter settings in a high resolution mode program.
Collapse
Affiliation(s)
- Andreas Buechner
- Department of Otolaryngology, Medizinische Hochschule Hannover, Hannover, Germany.
| | | | | | | | | | | |
Collapse
|
9
|
Buechner A, Frohne-Buechner C, Stoever T, Gaertner L, Battmer RD, Lenarz T. Comparison of a paired or sequential stimulation paradigm with advanced bionics' high-resolution mode. Otol Neurotol 2006; 26:941-7. [PMID: 16151341 DOI: 10.1097/01.mao.0000185069.27705.f0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Simultaneous stimulation on two channels was investigated with respect to fully sequential stimulation while controlling for the number of channels and the stimulation rate used. STUDY DESIGN Only subjects having at least 6 months' experience with conventional Clarion speech coding strategies (CIS, PPS, or SAS) were included. A counterbalanced cross-over design was used to compare the paired stimulation paradigm to the sequential stimulation paradigm. SETTING The investigation was a prospective, within-subject, repeated-measures experiment. PATIENTS The study group consisted of 13 postlingually deafened adult subjects. INTERVENTIONS The following programs were evaluated: 1) 16-channel paired stimulation with 5000 pps per channel; 2) 16-channel sequential stimulation with 2500 pps per channel; and 3) 8-channel sequential stimulation with 5000 pps per channel. MAIN OUTCOME MEASURES Speech perception tests in quiet and noise, Quality Assessment Questionnaire. RESULTS On average, both sequential stimulation programs showed comparable results, whereas the program with paired stimulation, on average, provided poorer performance. Several subjects showed a remarkable drop in performance when changing from sequential to paired mode. Although a few subjects showed better performance in quiet when using paired stimulation, they still had poorer performance in noise. A weak trend was found linking the difference between program levels in paired or in sequential stimulation paradigm to the difference in performance with these two settings. CONCLUSION Results indicate that for all subjects in this group sequential stimulation is more appropriate than paired stimulation. Subjective reports, as well as formal speech perception testing, show that the difference between the two paradigms is pronounced, especially when evaluating in the presence of background noise, the test condition more representative of everyday listening.
Collapse
Affiliation(s)
- Andreas Buechner
- Department of Otolaryngology, Medizinische Hochschule Hannover, Hannover, Germany.
| | | | | | | | | | | |
Collapse
|
10
|
Xu L, Zwolan TA, Thompson CS, Pfingst BE. Efficacy of a cochlear implant simultaneous analog stimulation strategy coupled with a monopolar electrode configuration. Ann Otol Rhinol Laryngol 2006; 114:886-93. [PMID: 16363059 DOI: 10.1177/000348940511401113] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The present study was performed to evaluate the efficacy and clinical feasibility of using monopolar stimulation with the Clarion Simultaneous Analog Stimulation (SAS) strategy in patients with cochlear implants. METHODS Speech recognition by 10 Clarion cochlear implant users was evaluated by means of 4 different speech processing strategy/electrode configuration combinations; ie, SAS and Continuous Interleaved Sampling (CIS) strategies were each used with monopolar (MP) and bipolar (BP) electrode configurations. The test measures included consonants, vowels, consonant-nucleus-consonant words, and Hearing in Noise Test sentences with a +10 dB signal-to-noise ratio. Additionally, subjective judgments of sound quality were obtained for each strategy/configuration combination. RESULTS All subjects but 1 demonstrated open-set speech recognition with the SAS/MP combination. The group mean Hearing in Noise Test sentence score for the SAS/MP combination was 31.6% (range, 0% to 92%) correct, as compared to 25.0%, 46.7%, and 37.8% correct for the CIS/BP, CIS/MP, and SAS/BP combinations, respectively. Intersubject variability was high, and there were no significant differences in mean speech recognition scores or mean preference ratings among the 4 strategy/configuration combinations tested. Individually, the best speech recognition performance was with the subject's everyday strategy/configuration combination in 72% of the applicable cases. If the everyday strategy was excluded from the analysis, the subjects performed best with the SAS/MP combination in 37.5% of the remaining cases. CONCLUSIONS The SAS processing strategy with an MP electrode configuration gave reasonable speech recognition in most subjects, even though subjects had minimal previous experience with this strategy/configuration combination. The SAS/MP combination might be particularly appropriate for patients for whom a full dynamic range of electrical hearing could not be achieved with a BP configuration.
Collapse
Affiliation(s)
- Li Xu
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
| | | | | | | |
Collapse
|
11
|
Kós MI, Boëx C, Sigrist A, Guyot JP, Pelizzone M. Measurements of electrode position inside the cochlea for different cochlear implant systems. Acta Otolaryngol 2005; 125:474-80. [PMID: 16092536 DOI: 10.1080/00016480510039995] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
CONCLUSIONS This study demonstrates that the exact location of an electrode inside the cochlea needs to be assessed using two complementary measures, namely the length and angle of insertion, both of which are mandatory if one wants to prevent erroneous outcomes. Knowledge of the contact position may become very useful when tuning a cochlear implant processor in a patient with contralateral residual hearing, or in cases of binaural implants. OBJECTIVE Multichannel cochlear implants restore useful hearing to deaf patients. However, several types of intracochlear electrodes are presently available, each featuring a specific technology or design. The aim of this study was to determine precisely the intracochlear position of the contacts for different electrode arrays. MATERIAL AND METHODS Electrode array insertions were estimated using special radiographs. A total of 26 cochlear implantations were included in the study: 6 Ineraid; 5 Clarion HiFocus I; 11 Clarion HiFocus II; and 4 Med-El Combi40+. In each case, a measurable reference or marker ring placed close to the round window (within 2 mm) could be identified. Insertion lengths and angles were measured and then plotted on a graphl based on 3D reconstructions. RESULTS Both Clarion HiFocus I and II electrode arrays were found to be placed close to the inner wall of the cochlea. Ineraid and Med-El Combi40+ electrode arrays were both placed close to the organ of Corti, the Med-El Combi40+ arrays demonstrating the deepest insertions overall. In spite of marked differences in the positions of the contacts, we did not find any correlation with speech perception performance for the different types of implants studied.
Collapse
Affiliation(s)
- Maria-Izabel Kós
- Cochlear Implants Center, Department of Otolaryngology, Head and Neck Surgery, University Hospital, Geneva, Switzerland.
| | | | | | | | | |
Collapse
|
12
|
Zwolan TA, Kileny PR, Smith S, Waltzman S, Chute P, Domico E, Firszt J, Hodges A, Mills D, Whearty M, Osberger MJ, Fisher L. Comparison of Continuous Interleaved Sampling and Simultaneous Analog Stimulation Speech Processing Strategies in Newly Implanted Adults with a Clarion 1.2 Cochlear Implant. Otol Neurotol 2005; 26:455-65. [PMID: 15891649 DOI: 10.1097/01.mao.0000169794.76072.16] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE This study consisted of a within-subjects comparison of speech recognition and patient preference when subjects used two different cochlear implant speech processing strategies with a Clarion 1.2 (enhanced bipolar) device: Simultaneous Analog Stimulation (SAS), and Continuous Interleaved Sampling (CIS). These two strategies used two different electrode configurations: the SAS strategy used bipolar stimulation, whereas the CIS strategy used monopolar stimulation. STUDY DESIGN This was a multicenter study that used a within-subjects balanced crossover design. Experience with the two strategies was replicated in each subject using an ABAB design. Order of strategy use was balanced across all subjects. SETTING The study was carried out at several cochlear implant centers affiliated with tertiary medical centers. PATIENTS Subjects consisted of 25 postlingually deafened adults who received a Clarion cochlear implant. INTERVENTIONS Total involvement by each subject was 14 weeks. Speech perception testing and sound quality assessments were performed after use with each strategy. MAIN OUTCOME MEASURES Primary outcome measures include speech perception data and patient responses to questionnaires regarding speech and sound quality. RESULTS Analyses revealed that performance did not differ significantly by the strategy encountered first as relative to the strategy encountered second and that the order in which a strategy was used did not appear to affect subjects' eventual preference for a particular strategy. Although speech recognition scores tended to be higher for CIS for most of the test measures at most of the test intervals, the analysis of variance to evaluate differences in strategy did not reveal a significant effect of strategy. Further analysis of scores obtained at the replication interval, however, revealed that scores obtained with CIS were significantly higher than scores obtained with SAS on the Hearing in Noise Test sentences in quiet and noise. In addition, significantly more patients indicated a final preference for the CIS strategy than for the SAS strategy. Importantly, both the analysis evaluating order and the analysis evaluating strategy revealed significant effects of evaluation period, indicating that time/experience with the implant had a significant effect on scores for each strategy, regardless of the order in which it was used (first or second). CONCLUSIONS This study demonstrates that important learning occurs during the first several weeks of cochlear implant use, making it difficult to adequately compare performance with different speech processing strategies. However, the finding that patients often prefer the strategy they understand speech the best with supports the clinical practice of letting adult patients select their preferred strategy without formally evaluating speech perception with each available strategy.
Collapse
|
13
|
Firszt JB, Holden LK, Skinner MW, Tobey EA, Peterson A, Gaggl W, Runge-Samuelson CL, Wackym PA. Recognition of Speech Presented at Soft to Loud Levels by Adult Cochlear Implant Recipients of Three Cochlear Implant Systems. Ear Hear 2004; 25:375-87. [PMID: 15292777 DOI: 10.1097/01.aud.0000134552.22205.ee] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The purpose of this study was to conduct a large-scale investigation with adult recipients of the Clarion, Med-El, and Nucleus cochlear implant systems to (1) determine average scores and ranges of performance for word and sentence stimuli presented at three intensity levels (70, 60, and 50 dB SPL); (2) provide information on the variability of scores for each subject by obtaining test-retest measures for all test conditions; and (3) further evaluate the potential use of lower speech presentation levels (i.e., 60 and/or 50 dB SPL) in cochlear implant candidacy assessment. DESIGN Seventy-eight adult cochlear implant recipients, 26 with each of the three cochlear implant systems, participated in the study. To ensure that the data collected reflect the range of performance of adult recipients using recent technology for the three implant systems (Clarion HiFocus I or II, Med-El Combi 40+, Nucleus 24M or 24R), a composite range and distribution of consonant-nucleus-consonant (CNC) monosyllabic word scores was determined. Subjects using each device were selected to closely represent this range and distribution of CNC performance. During test sessions, subjects were administered the Hearing in Noise Test (HINT) sentence test and the CNC word test at three presentation levels (70, 60, and 50 dB SPL). HINT sentences also were administered at 60 dB SPL with a signal-to-noise ratio (SNR) of +8 dB. Warble tones were used to determine sound-field threshold levels from 250 to 4000 Hz. Test-retest measures were obtained for each of the speech recognition tests as well as for warble-tone sound-field thresholds. RESULTS Cochlear implant recipients using the Clarion, Med-El, or Nucleus devices performed on average equally as well at 60 compared with 70 dB SPL when listening for words and sentences. Additionally, subjects had substantial open-set speech perception performance at the softer level of 50 dB SPL for the same stimuli; however, subjects' ability to understand speech was poorer when listening in noise to signals of greater intensity (60 dB SPL + 8 SNR) than when listening to signals presented at a soft presentation level (50 dB SPL) in quiet. A significant correlation was found between sound-field thresholds and speech recognition scores for presentation levels below 70 dB SPL. The results demonstrated a high test-retest reliability with cochlear implant users for these presentation levels and stimuli. Average sound-field thresholds were between 24 and 29 dB HL for frequencies of 250 to 4000 Hz, and results across sessions were essentially the same. CONCLUSIONS Speech perception measures used with cochlear implant candidates and recipients should reflect the listening challenges that individuals encounter in natural communication situations. These data provide the basis for recommending new candidacy criteria based on speech recognition tests presented at 60 and/or 50 dB SPL, intensity levels that reflect real-life listening, rather than 70 dB SPL.
Collapse
Affiliation(s)
- Jill B Firszt
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Middlebrooks JC. Effects of cochlear-implant pulse rate and inter-channel timing on channel interactions and thresholds. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2004; 116:452-68. [PMID: 15296005 DOI: 10.1121/1.1760795] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Interactions among the multiple channels of a cochlear prosthesis limit the number of channels of information that can be transmitted to the brain. This study explored the influence on channel interactions of electrical pulse rates and temporal offsets between channels. Anesthetized guinea pigs were implanted with 2-channel scala-tympani electrode arrays, and spike activity was recorded from the auditory cortex. Channel interactions were quantified as the reduction of the threshold for pulse-train stimulation of the apical channel by sub-threshold stimulation of the basal channel. Pulse rates were 254 or 4069 pulses per second (pps) per channel. Maximum threshold reductions averaged 9.6 dB when channels were stimulated simultaneously. Among nonsimultaneous conditions, threshold reductions at the 254-pps rate were entirely eliminated by a 1966-micros inter-channel offset. When offsets were only 41 to 123 micros, however, maximum threshold shifts averaged 3.1 dB, which was comparable to the dynamic ranges of cortical neurons in this experimental preparation. Threshold reductions at 4069 pps averaged up to 1.3 dB greater than at 254 pps, which raises some concern in regard to high-pulse-rate speech processors. Thresholds for various paired-pulse stimuli, pulse rates, and pulse-train durations were measured to test possible mechanisms of temporal integration.
Collapse
Affiliation(s)
- John C Middlebrooks
- Kresge Hearing Research Institute, Department of Otorhinolaryngology, University of Michigan Medical School, 1301 E. Ann St., Ann Arbor, Michigan 48109-0506, USA.
| |
Collapse
|
15
|
Bierer JA, Middlebrooks JC. Cortical responses to cochlear implant stimulation: channel interactions. J Assoc Res Otolaryngol 2003; 5:32-48. [PMID: 14564662 PMCID: PMC2538368 DOI: 10.1007/s10162-003-3057-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2002] [Accepted: 07/28/2003] [Indexed: 11/25/2022] Open
Abstract
This study examined the interactions between electrical stimuli presented through two channels of a cochlear implant. Experiments were conducted in anesthetized guinea pigs. Multiunit spike activity recorded from the auditory cortex reflected the cumulative effects of electric field interactions in the cochlea as well as any neural interactions along the ascending auditory pathway. The cochlea was stimulated electrically through a 6-electrode intracochlear array. The stimulus on each channel was a single 80- micro s/phase biphasic pulse. Channel interactions were quantified as changes in the thresholds for elevation of cortical spike rates. Experimental parameters were interchannel temporal offset (0 to +/-2000 micro s), interelectrode cochlear spacing (1.5 or 2.25 mm), electrode configuration (monopolar, bipolar, or tripolar), and relative polarity between channels (same or inverted). In most conditions, presentation of a subthreshold pulse on one channel reduced the threshold for a pulse on a second channel. Threshold shifts were greatest for simultaneous pulses, but appreciable threshold reductions could persist for temporal offsets up to 640 micro s. Channel interactions varied strongly with electrode configuration: threshold shifts increased in magnitude in the order tripolar, bipolar, monopolar. Channel interactions were greater for closer electrode spacing. The results have implications for design of speech processors for cochlear implants.
Collapse
Affiliation(s)
- Julie Arenberg Bierer
- Kresge Hearing Research Institute, Department of Otorhinolaryngology, University of Michigan, Ann Arbor, MI 48109-0506, USA
| | - John C. Middlebrooks
- Kresge Hearing Research Institute, Department of Otorhinolaryngology, University of Michigan, Ann Arbor, MI 48109-0506, USA
| |
Collapse
|
16
|
Boëx C, de Balthasar C, Kós MI, Pelizzone M. Electrical field interactions in different cochlear implant systems. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2003; 114:2049-57. [PMID: 14587604 DOI: 10.1121/1.1610451] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The goal of this study was to evaluate electrical field interactions produced by the stimulation of different types of intracochlear electrodes in 12 adult subjects (three Ineraid, four Clarion S-Series, three S-Series with the electrode positioning system-EPS and two Clarion HiFocus-I with the EPS). Psychophysical measurements were conducted with biphasic stimuli (813 pulse per second, 153.8 micros/phase). "Perturbation" signals (300 ms) were applied to one electrode chosen at the middle of the array and their effects on detection thresholds of "probe" signals (30 ms) were measured on the neighbor basal electrode. Perturbation levels were set below the detection threshold of the perturbation electrode (-2 dB re threshold). Measurements were first conducted for simultaneous stimulation of the probe and of the perturbation electrodes, for monopolar for all subjects and for bipolar stimulus configurations for both Clarion HiFocus-I subjects. The tested Clarion electrodes did not present lower monopolar interactions than the Ineraid electrodes. Nevertheless, considering the shorter distance between electrodes for the Clarion than for the Ineraid, the tested Clarion electrodes might be more selective than the Ineraid. We did not find any significant monopolar electrical field-interaction differences between subjects who received the S-Series array with and without the EPS. We did not find lower interactions for both subjects who received the HiFocus-I array than for subjects who received the S-Series. Electrical field interactions were lower for bipolar than for monopolar configurations for both HiFocus-I subjects. A second set of measurements was conducted for nonsimultaneous stimulation similar to the one used in continuous interleaved sampling sound strategy. These measurements showed that interactions evaluated for simultaneous biphasic stimuli were larger than for nonsimultaneous stimulation.
Collapse
Affiliation(s)
- Colette Boëx
- Centre Romand d'Implants Cochléaires, University Hospital, CH-1211 Geneva 14, Switzerland.
| | | | | | | |
Collapse
|
17
|
Boëx C, Kós MI, Pelizzone M. Forward masking in different cochlear implant systems. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2003; 114:2058-65. [PMID: 14587605 DOI: 10.1121/1.1610452] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The goal of this study was to evaluate, from a psychophysical standpoint, the neural spread of excitation produced by the stimulation of different types of intracochlear electrode arrays: the Ineraid, the Clarion S-Series on its own or with the Electrode Positioning System (EPS), and the Clarion HiFocus-I with the EPS. The EPS is an independent silicone part designed to bring the electrode array close to the modiolus. Forward masking was evaluated in 12 adult subjects (3 Ineraid, 4 Clarion S-Series, 3 Clarion S-Series+EPS, 3 HiFocus-I+EPS) by psychophysical experiments conducted using trains of biphasic stimuli (813 pulses per second, 307.6 micros/phase). Masker signals (+8 dB re: threshold, 300 ms) were applied to the most apical electrode. Probe signals (30 ms, 10-ms postmasker) were delivered to more basal electrodes. Masked and unmasked detection thresholds of probe signals were measured. For both Clarion HiFocus-I subjects, measurements were conducted in both monopolar and bipolar stimulus configurations. No major differences were found in forward masking between the different intracochlear electrode arrays tested in the monopolar configuration at suprathreshold levels equivalent to those used in speech-coding strategies, but significant differences were found between subjects. A significant negative correlation also was found between the level of forward masking and the consonant identification performance. These measurements showed that the neural spread of excitation was more restricted in the bipolar configuration than in the monopolar configuration for HiFocus-I subjects. It was found that CIS strategies implemented without using apical electrodes, which showed high levels of masking, could improve consonant identification.
Collapse
Affiliation(s)
- Colette Boëx
- Centre Romand d'Implants Cochléaires, University Hospital, Geneva, Switzerland.
| | | | | |
Collapse
|
18
|
Raggio MW, Schreiner CE. Neuronal responses in cat primary auditory cortex to electrical cochlear stimulation: IV. Activation pattern for sinusoidal stimulation. J Neurophysiol 2003; 89:3190-204. [PMID: 12783954 DOI: 10.1152/jn.00341.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Patterns of threshold distributions for single-cycle sinusoidal electrical stimulation and single pulse electrical stimulation were compared in primary auditory cortex of the adult cat. Furthermore, the effects of auditory deprivation on these distributions were evaluated and compared across three groups of adult cats. Threshold distributions for single and multiple unit responses from the middle cortical layers were obtained on the ectosylvian gyrus in an acutely implanted animal; 2 wk after deafening and implantation (short-term group); and neonatally deafened animals implanted following 2-5 yr of deafness (long-term group). For all three cases, we observed similar patterns of circumscribed regions of low response thresholds in the region of primary auditory cortex (AI). A dorsal and a ventral region of low response thresholds were found separated by a narrow, anterior-posterior strip of elevated thresholds. The ventral low-threshold regions in the short-term group were cochleotopically arranged. By contrast, the dorsal region in the short-term animals and both low-threshold regions in long-term deafened animals maintained only weak cochleotopicity. Analysis of the spatial extent of the low-threshold regions revealed that the activated area for sinusoidal stimulation was smaller and more circumscribed than for pulsatile stimulation for both dorsal and ventral AI. The width of the high-threshold ridge that separated the dorsal and ventral low-threshold regions was greater for sinusoidal stimulation. Sinusoidal and pulsatile threshold behavior differed significantly for electrode configurations with low and high minimum thresholds. Differences in threshold behavior and cortical response distributions between the sinusoidal and pulsatile stimulation suggest that stimulus shape plays a significant role in the activation of cortical activity. Differences in the activation pattern for short-term and long-term deafness reflect deafness-induced reorganizational changes based on factors such as differences in excitatory and inhibitory balance that are affected by the stimulation parameters.
Collapse
Affiliation(s)
- Marcia W Raggio
- Epstein Laboratory, Coleman Laboratory, Department of Otolaryngology, University of California at San Francisco, 94143-0732, USA.
| | | |
Collapse
|
19
|
Loizou PC, Stickney G, Mishra L, Assmann P. Comparison of speech processing strategies used in the Clarion implant processor. Ear Hear 2003; 24:12-9. [PMID: 12598809 DOI: 10.1097/01.aud.0000052900.42380.50] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the performance of the various speech processing strategies supported by the Clarion S-Series implant processor. DESIGN Five different speech-processing strategies [the Continuous Interleaved Sampler (CIS), the Simultaneous Analog Stimulation (SAS), the Paired Pulsatile Sampler (PPS), the Quadruple Pulsatile Sampler (QPS) and the hybrid (HYB) strategies] were implemented on the Clarion Research Interface platform. These speech-processing strategies varied in the degree of electrode simultaneity, with the SAS strategy being fully simultaneous (all electrodes are stimulated at the same time), the PPS and QPS strategies being partially simultaneous and the CIS strategy being completely sequential. In the hybrid strategy, some electrodes were stimulated using SAS, and some were stimulated using CIS. Nine Clarion CIS users were fitted with the above speech processing strategies and tested on vowel, consonant and word recognition in quiet. RESULTS There were no statistically significant differences in the mean group performance between the CIS and SAS strategies on vowel and sentence recognition. A statistically significant difference was found only on consonant recognition. Individual results, however, indicated that most subjects performed worse with the SAS strategy compared with the CIS strategy on all tests. About 33% of the cochlear implant users benefited from the PPS and QPS strategies on consonant and word recognition. CONCLUSIONS If temporal information were the primary factor in speech recognition with cochlear implants then SAS should consistently produce higher speech recognition scores than CIS. That was not the case, however, because most CIS users performed significantly worse with the SAS strategy on all speech tests. Hence, there seems to be a trade-off between improving the temporal resolution with an increasing number of simultaneous channels and introducing distortions from electrical-field interactions. Performance for some CI users improved when the number of simultaneous channels increased to two (PPS strategy) and four (QPS strategy). The improvement with the PPS and QPS strategies must be due to the higher rates of stimulation. The above results suggest that CIS users are less likely to benefit with the SAS strategy, and they are more likely to benefit from the PPS and QPS strategies, which provide higher rates of stimulation with small probability of channel interaction.
Collapse
Affiliation(s)
- Philipos C Loizou
- Department of Electrical Engineering, University of Texas at Dallas, Richardson 75083-0688, USA.
| | | | | | | |
Collapse
|
20
|
Frijns JHM, Briaire JJ, de Laat JAPM, Grote JJ. Initial evaluation of the Clarion CII cochlear implant: speech perception and neural response imaging. Ear Hear 2002; 23:184-97. [PMID: 12072611 DOI: 10.1097/00003446-200206000-00003] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the new Clarion CII cochlear implant with the perimodiolar HiFocus electrode array, including both speech perception outcomes and the device's capabilities of measuring the electrically evoked compound action potential (eCAP) of the auditory nerve (Neural Response Imaging, NRI). DESIGN The speech perception scores on CVC words without lip reading were monitored prospectively for the 10 postlingually deaf patients implanted with the Clarion CII device in the period July 2000 until May 2001 in the Leiden University Medical Center. Preoperative and postoperative NRI recordings were made, applying various combinations of monopolar stimulating and recording electrodes with the alternating polarity paradigm available in the test bench software. RESULTS Nine patients preferred the CIS, one the PPS strategy, none the SAS strategy. With their favorite strategy they acquired significant open set speech understanding within a few weeks, resulting in an average CVC phoneme score of 84% (word score 66%) at the end of the study (follow-up 3 to 11 mo). In speech-shaped noise, the average phoneme recognition threshold (PRT) was reached at a signal to noise ratio just below 0 dB. The NRI recordings had clear N1 and P1 peaks if there was at least one contact between the stimulating and recording electrodes, necessitating just 15 sweeps for a reliable recording. We observed considerable inter-patient and inter-electrode variability, but for a given situation NRI input/output curves were stable over time. More apical contacts generally elicited larger eCAPs. Response amplitudes tended to peak at recording sites around apical and basal stimulating electrodes, suggesting a limited spread of excitation. Preliminary recordings with the forward masking paradigm were consistent with the ones with the alternating polarity scheme. CONCLUSIONS The Clarion CII is a promising cochlear implant with which our first 10 patients have obtained excellent speech perception results. The NRI system yields high quality signals with a limited number of sweeps at a high sampling rate.
Collapse
Affiliation(s)
- Johan H M Frijns
- ENT-Department, Room J2-57, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | | | | | | |
Collapse
|
21
|
Moore CM, Vollmer M, Leake PA, Snyder RL, Rebscher SJ. The effects of chronic intracochlear electrical stimulation on inferior colliculus spatial representation in adult deafened cats. Hear Res 2002; 164:82-96. [PMID: 11950528 DOI: 10.1016/s0378-5955(01)00415-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Previous studies have shown that chronic electrical stimulation through a cochlear implant causes significant alterations in the central auditory system of neonatally deafened cats. The goal of this study was to investigate the effects of chronic stimulation in the mature auditory system. Normal hearing adult animals were deafened by ototoxic drugs and received daily electrical stimulation over periods of 4-6 months. In terminal physiology experiments, response thresholds to pulsatile and sinusoidal signals were recorded within the inferior colliculus (IC). Using previously established methods, spatial tuning curves (STCs; threshold vs. IC depth functions) were constructed, and their widths measured to infer spatial selectivity. The IC spatial representations were similar for pulsatile and sinusoidal stimulation when phase duration was taken into consideration. However, sinusoidal signals consistently elicited much lower thresholds than pulsatile signals, a difference not solely attributable to differences in charge/phase. The average STC width was significantly broader in the adult deafened/stimulated animals than in controls (adult deafened/unstimulated cats), suggesting that electrical stimulation can induce spatial expansion of the IC representation of the chronically stimulated cochlear sector. Further, results in these adult animals were not significantly different from results in neonatally deafened, early stimulated animals, suggesting that a similar degree of plasticity was induced within the auditory midbrains of mature animals.
Collapse
Affiliation(s)
- Charlotte M Moore
- Epstein Laboratory, Department of Otolaryngology, Room U490, University of California, San Francisco 94143-0526, USA.
| | | | | | | | | |
Collapse
|
22
|
Stollwerck LE, Goodrum-Clarke K, Lynch C, Armstrong-Bednall G, Nunn T, Markoff L, Mens L, McAnallen C, Wei J, Boyle P, George C, Zilberman Y. Speech processing strategy preferences among 55 European CLARION cochlear implant users. SCANDINAVIAN AUDIOLOGY. SUPPLEMENTUM 2001:36-8. [PMID: 11318477 DOI: 10.1080/010503901300007001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
This multicentre study investigates the preference and performance of a group of 55 adult CLARION cochlear implant users with the choice of simultaneous analogue stimulation (SAS) and continuous interleaved sampler (CIS) strategies during the first 3 months of implant use. Subjects were programmed with both strategies and instructed to use each of the two strategies in daily life to ascertain preference. Subjects were tested in both strategies with open-set sentence materials, auditory alone, at 2, 6 and 12 weeks after the initial programming session. Questionnaires were completed with preference ratings being recorded for the two strategies: 25% of subjects preferred SAS and 75% CIS. Subjects performed better in their strategy of choice. Preferences were set very early on in the process and did not change. Factors influencing preference are discussed. Offering the choice of fundamentally different strategies improves both individual and group performance.
Collapse
Affiliation(s)
- L E Stollwerck
- UCL Cochlear Implant Programme, Royal National Throat, Nose and Ear Hospital, London, UK
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Rebscher SJ, Snyder RL, Leake PA. The effect of electrode configuration and duration of deafness on threshold and selectivity of responses to intracochlear electrical stimulation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2001; 109:2035-2048. [PMID: 11386556 DOI: 10.1121/1.1365115] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This report examines the effects of intracochlear electrode configuration and mode of stimulation (bipolar or monopolar) on neural threshold and spatial selectivity in the inferior colliculus (IC) of the cat. Single and multiunit IC recordings were made in three groups of animals; acutely deafened adults (controls), neonatally deafened animals studied at 6 to 18 months of age and neonatally deafened cats studied at 2.5 to 6.5 years. Response thresholds were plotted versus IC depth to measure the spatial distribution of responses. The response selectivity for each stimulating configuration was defined as the width of the resulting spatial tuning curve (STC) measured at 6 dB above threshold. Spiral ganglion cell (SG) survival was examined histologically in all neonatally deafened animals and correlated with physiological results. Animals studied at less than 1.5 years had SG densities of 23.5%-64.4% of normal (mean=42.7%) while animals studied at greater than 2.5 years had densities of 5.1%-18.3% of normal (mean=9.9%). Electrophysiological results include the following. (1) Monopolar thresholds were 7-8 dB lower than bipolar thresholds in the same animals. (2) Varying the configuration of bipolar contacts (measured as radial, offset radial and longitudinal pairs) did not systematically affect IC threshold in either controls or short-term neonatally deafened animals. In contrast, the long-term neonatally deafened animals showed a difference in threshold with each configuration. (3) The spatial distributions (Q(6 dB)) of responses to bipolar stimulation were approximately 40% more restricted than those for monopolar stimulation. (4) The spatial selectivity of neonatally deafened animals studied at ages up to 1.5 years was equal to that of control animals with normal auditory experience. However, selectivity was degraded in the older animals. (5) Selectivity was decreased in some animals with the longitudinal bipolar configuration and multiple response peaks were seen in several cases using this stimulus configuration.
Collapse
Affiliation(s)
- S J Rebscher
- Department of Otolaryngology, University of California, San Francisco 94143-0526, USA.
| | | | | |
Collapse
|
24
|
Battmer RD, Goldring JE, Kanert W, Meyer V, Bertram B, Lenarz T. Simultaneous analog stimulation pilot pediatric study. THE ANNALS OF OTOLOGY, RHINOLOGY & LARYNGOLOGY. SUPPLEMENT 2000; 185:58-60. [PMID: 11141005 DOI: 10.1177/0003489400109s1224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- R D Battmer
- Department of Experimental Otology, Medical University of Hannover, Germany
| | | | | | | | | | | |
Collapse
|