Steven J. Staller

Summary of Results Using the Nucleus CI24M implant to record the electrically evoked compound action potential

OBJECTIVE This study outlines a series of experiments using the neural response telemetry (NRT) system of the Nucleus CI24M cochlear implant to measure the electrically evoked compound action potential (EAP). The goal of this investigation was to develop a protocol that allows successful recording of the EAP in a majority of CI24M cochlear implant users. DESIGN Twenty-six postlingually deafened adults participated in this study. A series of experiments were conducted that allowed us to examine how manipulation of stimulation and recording parameters may affect the morphology of the EAP recorded using the Nucleus NRT system. RESULTS Results of this study show consistent responses on at least some electrodes from all subjects. Cross-subject and cross electrode variations in both the growth of the response and the temporal refractory properties of the response were observed. The range of stimulus and recording parameters that can be used to record the EAP with the Nucleus NRT system is described. CONCLUSIONS Using the protocol outlined in this study, it is possible to reliably record EAP responses from most subjects and for most electrodes in Nucleus CI24M cochlear implant users. These responses are robust and recording these responses does not require that the subject sleep or remain still. Based on these results, a specific protocol is proposed for measurement of the EAP using the NRT system of the CI24M cochlear implant. Potential clinical implications of these results are discussed.

Factors Affecting Auditory Performance of Postlinguistically Deaf Adults Using Cochlear Implants

A model of auditory performance and a model of ganglion cell survival in postlinguistically deafened adult cochlear implant users are suggested to describe the effects of aetiology, duration of deafness, age at implantation, age at onset of deafness, and duration of implant use. The models were compared with published data and a composite data set including 808 implant users. Qualitative agreement with the model of auditory performance was found. Duration of deafness had a strong negative effect on performance. Age at implantation had a slight negative effect on performance, increasing after age 60 years. Age at onset of deafness had little effect on performance up to age 60. Duration of implant use had a positive effect on performance. Aetiology had a relatively weak effect on performance.

The nucleus 24 contour cochlear implant system : adult clinical trial results

Objective The purpose of this article is to present psychophysical data for 40 Nucleus® 24 Contour™ adult patients with 1 mo of device experience and speech perception results for a group of 56 adult patients with 3 mo experience using the Nucleus 24 Contour cochlear implant system. Postoperative hearing thresholds (i.e., under headphones) in the implanted ear were also assessed in a group of 85 patients who had measurable hearing preoperatively. This was of interest because preservation of residual hearing, postoperatively, is consistent with atraumatic insertion of the electrode array. In addition, data will be presented that reflected feedback from 40 surgeons who participated in the trial. Design Participants in this study were 18 yr of age or older, with bilateral severe to profound sensorineural hearing loss with no congenital component. Preoperatively, they scored ≤50% open-set sentence recognition (HINT sentences) in the ear to be implanted and ≤60% in the best-aided condition. The investigation was a repeated-measures single-subject experiment and took place at 46 different North American clinical sites. Preoperative performance was compared with postoperative performance 3 mo after device activation. Clinicians were able to program patients’ processors with one, two, or all three speech-processing strategies. Testing took place using the participant’s preferred speech-processing strategy (SPEAK, CIS, or ACE™). Preoperative unaided hearing thresholds were compared with unaided thresholds in the implanted ear measured 1 mo after device activation. Surgeons were canvassed regarding surgical use and design of the device via a questionnaire after having completed at least one Nucleus 24 Contour surgery. Results Average T- and C-levels for the Nucleus 24 Contour patients were considerably lower than those using the Nucleus 24 (CI24M). A total of 85 patients had measurable hearing preoperatively at two or more audiometric frequencies in the ear implanted. Of these patients 41 (48%) had measurable hearing at one or more frequencies and 32 (38%) had measurable hearing at two or more frequencies postoperatively. In general, surgeons found the Nucleus 24 Contour easy to insert and were pleased with the design features of the device. The downsized receiver/stimulator (of the Nucleus 24 Contour) required less drilling than the Nucleus 24, reducing surgical time, as well as making the Contour better suited for implantation in those with small skull sizes (e.g., small children and infants). After 3 mo of device use, mean open-set speech perception in quiet and in noise was significantly better than preoperative performance on all test measures. Patients using the ACE strategy had significantly better mean scores for all measures than patients using SPEAK. Only two patients preferred to use the CIS coding strategy. Conclusions The results presented in this article demonstrated that the design objectives of the Nucleus 24 Contour were met. Namely, results from this study, together with insertion studies, were consistent with perimodiolar placement using an implant design that the majority of surgeons found easy to insert with relatively minimal trauma. Reduced T- and C-levels were observed with Contour patients when compared with patients using the Nucleus 24 with the straight array, consistent with perimodiolar placement. A survey of surgeons participating in the clinical trial indicated easier, or equally easy, insertion of the Contour array, compared with previous Nucleus products as well as other manufacturers’ devices, without the use of additional insertion tools or array positioners. Postoperatively, 46% of patients with preoperative residual hearing maintained some level of unaided hearing postoperatively, suggesting atraumatic insertion of the Nucleus 24 Contour electrode array. It is worth noting that all 216 patients implanted during this study had full insertions of their Contour electrode arrays. High levels of open-set speech perception in quiet and in noise were achieved and patients using the ACE strategy had significantly better mean scores for all measures than patients using SPEAK. Only two patients preferred to use the CIS coding strategy.

Nucleus® 24 Advanced Encoder conversion study: Performance versus preference

Objective The Nucleus® 24 Advanced Encoder Conversion Study was designed to determine the safety and effectiveness of the advanced combination encoder (ACE) and continuous interleaved sampling (CIS) speech coding strategies compared with that of the spectral peak (SPEAK) strategy in a large sample of postlinguistically deaf adults. Data from this study were analyzed to test the hypothesis that the group of subjects who prefer a given strategy for use in everyday life obtain significantly higher speech recognition scores (as a group) with the preferred strategy than with nonpreferred ones. Design The first 100 adults implanted with the Nucleus 24 Cochlear Implant System who had a minimum of 3 mo experience with the device were invited to participate. Those who accepted were randomly assigned to one of two groups for an initial 6-wk use of either the ACE or the CIS strategy; the other strategy was used during the second 6-wk period. Parameters in subjects’ SPrint™ speech processor programs were adjusted to maximize perceived benefit with each strategy in everyday life. Recognition of medial consonants and vowels, CNC words, CUNY sentences in quiet and at +10 dB signal to noise ratio, and HINT sentences in quiet was initially evaluated at the beginning of the study with the SPEAK strategy and at the end of the two 6-wk periods with the ACE and CIS strategies. Then subjects’ processors were programmed with all three strategies for use in everyday life. After 3-wk use, a final evaluation of speech recognition with the HINT sentences in quiet and CUNY sentences at +10 dB signal to noise ratio was performed with each strategy. Subjects also responded to a questionnaire giving their strategy preference for most listening situations, the percentage of time they used each strategy, and the strategy they found gave them the best hearing and understanding of speech in 19 listening situations. Results Of the 62 subjects who participated, 56 subjects reported that they preferred one strategy for most listening situations (ACE strategy: 37 [59.7%]; SPEAK strategy: 14 [22.6%]; CIS strategy: 5 [8.0%]) and six subjects did not prefer a single strategy (9.7%). For the group who preferred one strategy, the preferred strategy resulted in higher scores than for one of the other strategies at the initial evaluation on CUNY sentences in quiet and noise and at the final evaluation on HINT sentences in quiet and CUNY sentences in noise for approximately two-thirds of the subjects. Strategy preference and performance were not significantly related for the remaining dependent measures. There also was strong agreement between the preferred strategy, percentage time this strategy was used, and the number of specific listening situations the preferred strategy was chosen for best hearing and understanding of speech. Although the majority of subjects strongly preferred a single strategy, some preferred to use two or three strategies, and a few were not sure which strategy they preferred for the majority of listening situations. Of the 19 subjects who reported that it was useful to use different strategies for different listening situations, only 5 of the 13 subjects, who responded to a follow-up questionnaire sent 18 mo later, continued to use multiple strategies. Conclusions There was a significant relation between subjects’ strategy preference based on experience in everyday life and their performance on the sentence tests, particularly sentences in noise. Important individual differences in strategy preference as well as in rate and number of channels stimulated per cycle within the ACE and CIS strategies emerged during the study. At the end of this process, over half of the subjects preferred the ACE strategy, and over double the number preferred the SPEAK strategy compared with the CIS strategy. To provide newly implanted recipients with as much benefit as possible, it is important that the speech processor program with each strategy be adjusted to maximize perceived benefit sequentially and then the three strategies need to be compared. With the four memories of the SPrint™ processor and a recipient who adapts quickly to hearing sound with different speech coding strategies, it may be possible to accomplish this comparison clinically through weekly fitting sessions plus listening in everyday life over a period of approximately 6 wk. At the end of this fitting process, most recipients probably will prefer to use one strategy, whereas some may prefer two or all three strategies to maximize their ability to hear in different listening situations.

Perceptual abilities of children with the nucleus 22-channel cochlear implant

THE PRIMARY OBJECTIVE of the clinical trials in children was to demonstrate that the Nucleus cochlear implant was safe and effective in this population. The demonstration of effectiveness was thought to primarily relate to improvements in speech perception skills, with and without lipreading, after implantation. For postoperative benefit to be considered meaningful, performance with the implant was required to significantly exceed the child’s preoperative performance in the better hearing ear. Best-aided performance preoperatively was typically with binaural amplification, or in about one-quarter of the subjects, vibrotactile devices. As was described in detail by Mecklenburg et al (see Chap. 2), for the purposes of the clinical trial each child was an individual experiment. Preto postoperative changes in performance were analyzed for each test on each child to determine the effectiveness of the device. The data from 80 subjects were analyzed in this manner and on the basis of these data, the Food and Drug Administration granted marketing approval on June 27, 1990. With the accrual of additional patient data since that time, the focus of research interest broadened to include the following questions: (1 ) does performance improve significantly after implantation; (2) does performance continue to improve with longer term experience using the implant; (3) are there factors that predict performance on speech perception measures; (4) do children with congenital deafness achieve the same skill level postoperatively as do children who acquired language before the onset of deafness; and (5) does the type and effectiveness of postoperative rehabilitation influence overall performance.

Summating potential in Meniere's disease.

This study assesses several electrocochleographic (ECoG) duration and amplitude measures in a clinically defined Menieres group and compares the results with those from a normal hearing control group and a hearing loss group (cochlear). The summating potential (SP)/action potential (AP) amplitude ratio was the most efficient diagnostic measure, with 62% of the Menieres group demonstrating abnormal ratios compared to 4% of the normal control group and 17% of the cochlear group.

Multichannel auditory brainstem implant: US clinical trial results.

Since 1994, a US Food and Drug Administration clinical trial evaluated the multichannel auditory brainstem implant (ABI) on 92 subjects with neurofibromatosis type 2 (NF2). The trial has shown that 85 per cent of patients receive auditory sensations. A small number of patients demonstrate a clinically significant degree of open-set sentence recognition in the sound-alone condition; however, when the ABI is combined with lip-reading cues, 93 per cent of patients demonstrate improved sentence understanding at three to six months. In addition, the majority of recipients report daily use of their devices, and satisfaction with the decision to receive the ABI.

Scope and design of the clinical trial of the nucleus multichannel cochlear implant in children

Although much has been learned in the 5 yr since the first child received a multichannel cochlear implant, we remain at the very early stages of this endeavor. The current evaluation procedures and performance data detailed in subsequent chapters represent the continuation of the efforts described above.

Evaluation and device programming in children.

PEDIATRIC CLINICAL TRIALS with the Nucleus 22-channel cochlear implant system began in 1986 and officially ended in June 1990 when the United States Food and Drug Administration (FDA) approved this device for commercial use in children ages 2 yr and older. Currently, over 500 children worldwide have received this multichannel implant. In this chapter, we describe the preoperative evaluation process, selection criteria, and the methods used in programming the device in young children.

Long‐term performance of prelinguistically deaf children using the Nucleus 22 channel cochlear implant.

A sample of 178 children have been followed annually for the past five years, to assess the development of speech perception abilities in early deafened children using a multichannel cochlear implant. A subset of these children who acquired deafness prior to the acquisition of language (prelinguistic) have shown continued improvement on a hierarchy of pediatric speech perception tests throughout the follow‐up period. Implantation at an early age appears to improve the prognosis for development of more difficult speech perception skills. In addition, there appears to be a positive relationship between the emphasis on oral listening skills and the rate of acquisition of speech perception abilities. Throughout the duration of the longitudinal study, several new speech processing strategies have been introduced for the Nucleus implant system. The most recent (SPEAK) is an adaptive strategy that varies the rate of stimulation and the number of electrode is stimulated according to the frequency characteristics ...