Modiolar coiling, electrical thresholds, and speech perception after cochlear implantation using the nucleus contour advance electrode with the advance off stylet technique.

OBJECTIVE: Perimodiolar electrode arrays were developed in an attempt to improve stimulation of specific neural populations and to decrease electrical thresholds, thereby decreasing power consumption. Postoperative radiographs show that coiling of the arrays is variable. Our previous study explored the relationship between the angle of coiling, threshold levels, and functional outcomes using the Nucleus Contour electrode array. This study compares coiling angle, electrical threshold levels, and speech perception measures with the Nucleus Contour Advance electrode array implanted using the new advance off stylet technique versus the Nucleus Contour electrode array implanted using the standard technique. STUDY DESIGN: Retrospective review. SETTING: University medical center. PATIENTS: Forty-two adults and children with normal cochlear anatomy implanted with the Nucleus CI24RCA electrode using the advance off stylet technique with at least 1-year follow-up. INTERVENTION: Therapeutic. MAIN OUTCOME MEASURES: Computer-aided radiographic analysis of perimodiolar electrode placement, electrical threshold measurements, and speech perception outcome measures at 1 year postimplantation. RESULTS: The degree of modiolar coiling was tighter using the new electrode and technique in comparison with standard insertion technique using the Nucleus Contour electrode array. The tighter coiling tended to result in higher electrical thresholds. Lower speech perception outcome measures tended to correlate with a higher degree of coiling. CONCLUSION: The Nucleus Contour Advance electrode array combined with the advance off stylet technique resulted in a more consistent perimodiolar position. However, the tighter coiling resulted in statistically significant increased electrical thresholds and decreased speech perception outcomes. This finding may be secondary to multiple factors, not just coiling angle.     

Electrophysiologic effects of placing cochlear implant electrodes in a perimodiolar position in young children

OBJECTIVE: The purpose of this study was to intraoperatively record the electrically evoked auditory brainstem response (EABR) before and after placement of the electrode positioning system (EPS) (CII Bionic Ear with HiFocus I cochlear implant electrode array) as well as before and after stylet removal (Nucleus Contour cochlear implant electrode array). It was hypothesized that physiologic changes would occur after perimodiolar positioning of the electrode array and these changes would be evident from the EABR recordings. STUDY DESIGN: Consecutive young (11-36 month old) pediatric cochlear implant recipients (n = 17) had intraoperative EABRs recorded from three intracochlear electrodes that represented apical, medial, and basal locations. Wave V amplitudes and thresholds were studied relative to electrode location and pre- versus postperimodiolar positioning. These evoked potential measures were analyzed for statistical significance. SETTING: Tertiary referral children's hospital/medical college. RESULTS: Wave V thresholds of the EABR were lower, and amplitudes were larger after perimodiolar positioning, although the changes were dependent on electrode location and implant design. Statistically significant decreases in EABR wave V threshold and increases in suprathreshold wave V amplitude were found for the basal electrode for the CII Bionic Ear HiFocus I and for the apical electrode for the Nucleus Contour. CONCLUSIONS: Placement of either the CII Bionic Ear HiFocus I or Nucleus Contour cochlear implant electrode array in the perimodiolar position in young children resulted in less electrical current necessary to stimulate the auditory system. Changes in electrophysiologic thresholds and amplitudes, measured with EABR, indicate that the electrode array is placed closer to the modiolus with both electrode designs.     

Comparison of speech perception performance between the nucleus 24 and nucleus 24 contour cochlear implant systems

Objective—To compare the 1-, 3-, and 6-month postoperative speech perception scores obtained by a group of subjects who received the new perimodiolar array (Nucleus Contour) cochlear implant with those obtained by a group of subjects implanted with the straight electrodes of the previous-generation Nucleus 24 device.

Material and Methods—The speech performance of 10 postlingually deafened adults implanted with the Nucleus Contour device was compared with that of matched controls who received the Nucleus 24 model. Objective measures included word and sentence speech recognition scores.

Results—Patients implanted with the Nucleus Contour device obtained significantly higher word and sentence recognition scores after short-term use of the implant compared to those obtained by patients implanted with the Nucleus 24 model.

Conclusion—Further long-term studies are required to determine whether the Nucleus Contour CI recipients continue to improve over time.     

Preservation of residual hearing with cochlear implantation: How and why

Conclusions Hearing may be conserved in adults after implantation with the Nucleus Contour Advance perimodiolar electrode array. The degree of hearing preservation and the maximum insertion depth of the electrode array can vary considerably despite a defined surgical protocol. Residual hearing combined with electrical stimulation in the same ear can provide additional benefits even for conventional candidates for cochlear implantation.

Objectives We present preliminary results from a prospective multicentre study investigating the conservation of residual hearing after implantation with a standard-length Nucleus Contour Advance perimodiolar electrode array and the benefits of combined electrical and acoustic stimulation.

Material and methods The subjects were 12 adult candidates for cochlear implantation recruited according to national selection criteria. A “soft” surgery protocol was defined, as follows: 1–1.2-mm cochleostomy hole anterior and inferior to the round window; Nucleus Contour Advance electrode array inserted using the “Advance-off-stylet” technique; and insertion depth controlled by means of three square marker ribs left outside the cochleostomy hole. These procedures had been shown to reduce insertion forces in temporal bone preparations. Variations in surgical techniques were monitored using a questionnaire. Pure-tone thresholds were measured pre- and postoperatively. Patients who still retained thresholds <90 dB HL for frequencies up to 500 Hz were re-fitted with an in-the-ear (ITE) hearing aid. Word recognition was tested in quiet and sentence perception in noise for the cochlear implant alone and in combination with an ipsilateral hearing aid.

Results Hearing threshold level data were available for 12 patients recruited from 6 of the centres. Median increases in hearing threshold levels were 23, 27 and 33 dB for the frequencies 125, 250 and 500 Hz, respectively. These median increases include the data for two patients who had total loss of residual hearing due to difficulties encountered during surgery. “Cochlear view” X-ray images indicated that the depth of insertion varied between 300 and 430°, despite modest variations in the length of the electrode inserted (17–19 mm). The insertion angle had some influence on the preservation of residual hearing at frequencies of 250–500 Hz. Six of the 12 patients retained sufficient hearing for effective use of an ipsilateral ITE hearing aid (≤80 dB HL at 125 and 250 Hz; ≤90 dB HL at 500 Hz). Word recognition scores in quiet were improved from 10% to 30% with the cochlear implant plus ipsilateral hearing aid in 3 patients who had at least 3 months postoperative experience. Signal:noise ratio thresholds for sentence recognition were improved by up to 3 dB. Patients reported that they experienced greatly improved sound quality and preferred to use the two devices together.     

Basic fitting and evaluation parameters of a newly designed cochlear implant electrode

Objective To validate a newly designed cochlear implant electrode (TRACE) in the standard monopolar mode and compare it to a patient group implanted with a standard Nucleus Contour? cochlear implant electrode. The electrode contacts of the TRACE electrode have the same active surface area for stimulation, but the position in the scala tympani is different from that of the Nucleus Contour? electrode.

Material and Methods The following parameters, used in cochlear implant fitting and evaluation procedures, were determined: the threshold and comfort stimulation current levels; the electrode impedances; and the phoneme discrimination and speech recognition scores using the ACE? speech algorithm.

Conclusion The new electrode does not differ significantly from the standard Nucleus Contour? electrode in terms of the investigated parameters within the test group.     

Reimplantation with a conventional length electrode following residual hearing loss in four hybrid implant recipients

Abstract

Hypothesis

Revision surgery using a newer-generation conventional length cochlear implant electrode will provide improved speech perception in patients that initially underwent hybrid electrode implantation and experienced post-operative loss of residual hearing and performance deterioration.

Clinical presentation

We present four patients who experienced delayed post-operative hearing loss following implantation with the Nucleus Hybrid S8 device and underwent reimplantation with the Nucleus Freedom or Nucleus 5 device using the Contour Advance array. Pure-tone thresholds and speech perception data were retrospectively reviewed.

Intervention

Four subjects underwent reimplantation with the Nucleus Freedom or Nucleus 5 device after experiencing deteriorating performance related to delayed acoustic hearing loss. Comparison of pre-revision performance to the most recent post-revision performance demonstrated improved speech perception performance in all subjects following reimplantation.

Conclusions

A small percent of patients will experience a significant loss of residual low-frequency hearing following hybrid implantation thereby becoming completely reliant on a shorter electrode for electrical stimulation. In the current series, reimplantation with a conventional length electrode provided improved speech perception performance in such patients. Revision surgery with a conventional length electrode should be considered in ‘short electrode’ recipients who experience performance deterioration following loss of residual hearing.     

Nucleus人工耳蜗弯电极和直电极植入后的心理物理指标比较

目的对比Nucleus CI 24导Contour弯电极与Nucleus CI 24导直电极植入后的电阻阻抗、刺激阈值和舒适阈。方法植入澳大利亚NucleuS人工耳蜗的患者分为2组,1组（19例）植入Nucleus CI 24导Contour电极阵列（弯电极）,另1组（11例）植入CI 24M电极阵列（直电极）。所有患者耳蜗植入术后15天开机调试,并于开机时及开机后1周、1月、3月分别记录各电极的电阻、刺激闽值和最大舒适阈。结果开机后由于Nucleus 24直电极的刺激阈值呈上升趋势,3月和6月时弯电极的阈值明显低于直电极阈值,且差异有统计学意义（P〈0．05）。开机1周、1月和6月2组的舒适阈接近。开机后弯电极和直电极的电阻值接近。结论Nucleus CI 24导Contour弯电极的刺激阈值稳定,刺激阈和舒适阈之间动态范围较宽。     

多导人工耳蜗植入后电极阻抗的初步研究

目的研究多导人工耳蜗植入后电极阻抗变化的特点,对比直电极和弯电极的阻抗差异,为人工耳蜗植入术后的调试提供参考。方法在Nucleus多导人工耳蜗编程调试界面上,应用R126V1.3和NRTV3.0软件,测试11例语前聋儿童在不同时期的阻抗值,并进行分析比较。结果CI24M和CI24Rcontour两种植入体阻抗随时间变化的基本规律是:术中较低,开机时最高,以后随时间推移逐渐降低。CI24Rcontour阻抗高于CI24M。结论人工耳蜗植入体阻抗开机后随时间推移而逐渐降低,新型CI24Rcontour植入体与CI24M相比,其阻抗值在术中至开机后3周内明显要高。     

Preservation of residual hearing with cochlear implantation: how and why

CONCLUSIONS: Hearing may be conserved in adults after implantation with the Nucleus Contour Advance perimodiolar electrode array. The degree of hearing preservation and the maximum insertion depth of the electrode array can vary considerably despite a defined surgical protocol. Residual hearing combined with electrical stimulation in the same ear can provide additional benefits even for conventional candidates for cochlear implantation. OBJECTIVES: We present preliminary results from a prospective multicentre study investigating the conservation of residual hearing after implantation with a standard-length Nucleus Contour Advance perimodiolar electrode array and the benefits of combined electrical and acoustic stimulation. MATERIAL AND METHODS: The subjects were 12 adult candidates for cochlear implantation recruited according to national selection criteria. A "soft" surgery protocol was defined, as follows: 1-1.2-mm cochleostomy hole anterior and inferior to the round window; Nucleus Contour Advance electrode array inserted using the "Advance-off-stylet" technique; and insertion depth controlled by means of three square marker ribs left outside the cochleostomy hole. These procedures had been shown to reduce insertion forces in temporal bone preparations. Variations in surgical techniques were monitored using a questionnaire. Pure-tone thresholds were measured pre- and postoperatively. Patients who still retained thresholds <90 dB HL for frequencies up to 500 Hz were re-fitted with an in-the-ear (ITE) hearing aid. Word recognition was tested in quiet and sentence perception in noise for the cochlear implant alone and in combination with an ipsilateral hearing aid. RESULTS: Hearing threshold level data were available for 12 patients recruited from 6 of the centres. Median increases in hearing threshold levels were 23, 27 and 33 dB for the frequencies 125, 250 and 500 Hz, respectively. These median increases include the data for two patients who had total loss of residual hearing due to difficulties encountered during surgery. "Cochlear view" X-ray images indicated that the depth of insertion varied between 300 and 430 degrees, despite modest variations in the length of the electrode inserted (17-19 mm). The insertion angle had some influence on the preservation of residual hearing at frequencies of 250-500 Hz. Six of the 12 patients retained sufficient hearing for effective use of an ipsilateral ITE hearing aid (< or = 80 dB HL at 125 and 250 Hz; < or = 90 dB HL at 500 Hz). Word recognition scores in quiet were improved from 10% to 30% with the cochlear implant plus ipsilateral hearing aid in 3 patients who had at least 3 months postoperative experience. Signal:noise ratio thresholds for sentence recognition were improved by up to 3 dB. Patients reported that they experienced greatly improved sound quality and preferred to use the two devices together.     

Hyperbaric oxygen therapy with short duration intratympanic steroid therapy for sudden hearing loss

Conclusions. Except for basal cochlear traumatization, all specimens implanted into scala tympani showed atraumatic insertion properties and good perimodiolar electrode positioning. Cochleostomy preparation and placement can have a significant impact on levels of basal cochlear trauma. Objective. In the past, perimodiolar cochlear implant electrodes increased the risk for intracochlear traumatization when compared to free-fitting arrays. Recently, however, clinical evidence for atraumatic perimodiolar implantations with preservation of residual hearing has been described. The aim of this paper was to histologically evaluate a perimodiolar cochlear implant array for its insertion properties in cadaver human temporal bones. Surgical and electrode factors, as well as preparation artifacts influencing intracochlear trauma, were considered in the evaluation. Materials and methods. Sixteen human temporal bones were harvested up to 24 hours post mortem and implanted immediately with the Nucleus 24 Contour Advance cochlear implant electrode array. Implantations were either performed using a regular caudal approach cochleostomy or through the round window membrane. After implantation, all bones underwent special histological processing, which allowed sectioning of undecalcified bone. Insertion properties were evaluated according to a grading system. Results. Fourteen specimens were implanted into scala tympani and only two exhibited basal trauma attributable to electrode insertion characteristics. Two bones were implanted into scala vestibuli after causing trauma in the region of the cochleostomy. Insertion depths ranged from 180° to 400°. All bones showed good perimodiolar electrode positioning. Basal trauma due to surgical issues and histological artifacts was present in 10 of 16 bones.     

Changes in psychophysical parameters during the first month of programming the Nucleus Contour and Contour Advance cochlear implants

Abstract

This retrospective study evaluated the psychophysical parameters of 29 postlingually deafened adults who had received a Nucleus Contour or Contour Advance implant during the first month of fitting in order to determine how many sessions were required to obtain a stable implant MAP. The T-levels did not differ significantly across the five fitting sessions, but the C-levels as well as the dynamic range showed an increase up to the fourth session. For all psychophysical parameters the basal, medial and apical portion of the electrode array differed significantly across sessions. Subjects with a Nucleus Contour implant had higher comfortable levels than subjects with a Contour Advance implant. The duration of deafness, presence of preoperative tinnitus, aetiology, frequency of fitting, stimulus rate and number of active channels did not significantly influence the psychophysical levels. These results suggested that four fitting sessions within the first three weeks after switch on should initially suffice and the fifth session could be planned beyond one month. Copyright © 2006 John Wiley & Sons, Ltd.     

Intra- and postoperative electrode impedance of the straight and Contour arrays of the Nucleus 24 cochlear implant: relation to T and C levels

The objective of this study was to investigate electrode impedance in cochlear implant recipients in relation to electrically evoked stapedius reflex measurements during surgery, and to electrode design, stimulation mode, and T and C levels over a nine month period after surgery. Seventy-five implant recipients, implanted with a Nucleus straight electrode array or a Contour array, were included. The results show that: (1) during surgery electrode impedance decreases markedly after electrically evoked stapedius reflex measurements, (2) after surgery, during the period without stimulation until speech processor switch-on, impedance increases, (3) after processor switch-on impedance decreases. The lower impedance values after a period of stimulation are found at the higher T and C levels. Impedances of the straight array electrodes are lower than those of the Contour array. The difference corresponds mainly to their respective surface areas. In addition, the straight array shows a larger increase of impedance in the apical direction than the Contour array, probably because of the larger fluid environment around the basal electrodes of the straight array.     

The Nucleus Contour electrode array: a radiological and histological study

OBJECTIVES: To evaluate the handling and insertion trauma of the recently developed Nucleus perimodiolar Contour electrode array (Cochlear Ltd., Pty, Lane Cove, New South Wales, Australia) in human temporal bones compared with the Nucleus standard straight electrode array. STUDY DESIGN: E-perimental control group. METHODS: Twenty-nine fresh-frozen bones were implanted with different electrode arrays by an experienced cochlear implant surgeon, and evaluated both radiologically and histologically. RESULTS: Intracochlear insertion of the standard Nucleus straight electrode array was found to be atraumatic, confirming previous findings in the literature. Insertion of the Nucleus Contour electrode array resulted in instances of localized basilar membrane penetration causing the electrode array to move from the scala tympani into the scala vestibuli. However, this trauma did not result in any observable damage to the osseous spiral lamina or the modiolus. Basilar membrane penetration was observed in six of eight cochlear bones when a standard cochleostomy size (approximately 0.8 mm) and site (anterior and superior to the round window) were used. However, when the surgical technique was modified to use a slightly larger cochleostomy ( approximately 1.8 mm) situated closer to the round window and employ a partial stylet withdrawal technique during electrode insertion, the frequency of penetrations was restricted to two of seven bones. This trauma rate is comparable to that observed with other cochlear implants designs. CONCLUSIONS: Following our results, the design of the Nucleus Contour electrode appears to fulfill the safety requirements for an intracochlear electrode array, provided that the surgical insertion technique is modified in the manner outlined.     

Surgical implications of perimodiolar cochlear implant electrode design: avoiding intracochlear damage and scala vestibuli insertion

Abstract

Objective To review the mechanisms and nature of intracochlear damage associated with cochlear implant electrode array insertion, in particular, the various perimodiolar electrode designs. Make recommendations regarding surgical techniques for the Nucleus Contour electrode to ensure correct position and minimal insertion trauma.

Background The potential advantages of increased modiolar proximity of intracochlear multichannel electrode arrays are a reduction in stimulation thresholds, an increase in dynamic range and more localized neural excitation. This may improve speech perception and reduce power consumption. These advantages may be negated if increased intracochlear damage results from the method used to position the electrodes close to the modiolus.

Method A review of the University of Melbourne Department of Otolaryngology experience with temporal bone safety studies using the Nucleus standard straight electrode array and a variety of perimodiolar electrode array designs; comparison with temporal bone insertion studies from other centres and postmortem histopathology studies reported in the literature. Review of our initial clinical experience using the Nucleus Contour electrode array.

Results The nature of intracochlear damage resulting from electrode insertion trauma ranges from minor, localized, spiral ligament tear to diffuse organ of Corti disruption and osseous spiral lamina fracture. The type of damage depends on the mechanical characteristics of the electrode array, the stiffness, curvature and size of the electrode in relation to the scala, and the surgical technique. The narrow, flexible, straight arrays are the least traumatic. Pre-curved or stiffer arrays are associated with an incidence of basilar membrane perforation. The cochleostomy must be correctly sited in relation to the round window to ensure scala tympani insertion. A cochleostomy anterior to the round window rather than inferior may lead to scala media or scala vestibuli insertion.

Conclusion Proximity of electrodes to the modiolus can be achieved without intracochlear damage provided the electrode array is a free fit within the scala, of appropriate size and shape, and accurate scala tympani insertion is performed.     

Evaluation of the insertion-trauma of the Nucleus Contour Advance electrode-array in a human temporal bone model

BACKGROUND: The development of intracochlear electrode arrays is aiming at a placement close to the modiolus with an insertion as atraumatic as possible. A new perimodiolar electrode model the Nucleus Contour Advance was to be evaluated regarding the possible intracochlear trauma. METHODS: The implantation of the Contour Advance electrode was performed in 11 frozen native temporal bones. Beneath a regular insertion in 5 temporal bones in 6 cases the insertion was carried out using the "advance-off-stylett" technique with a fixed stylett. The temporal bones were embedded in metacrylate based resin for histomorphological evaluation. The evaluation was performed regarding to the intracochlear placement close to the modiolus and the damage to intracochlear fine structures (basilar membrane, osseus spiral lamina). RESULTS: In 2 out of 11 cases we found a perforation from the scala tympani to the scala vestibuli independent of the insertion-technique. A severe intracochlear trauma was observed in one case with fracture of osseus spiral lamina using the AOS-technique. A close position to the modiolus could be achieved by insertion the scala tympani without perforation of the basilar membrane. CONCLUSIONS: The Nucleus Contour Advance electrode array showed minimal trauma in human temporal bones by using a standard insertion technique. By using the freehand AOS-technique a severe cochlear trauma is possible. Therefore further development in electrode design and the use of an insertion-tool is recommended.     

Intra- and postoperative electrode impedance of the straight and Contour arrays of the Nucleus 24 cochlear implant: Relation to T and C levels

The objective of this study was to investigate electrode impedance in cochlear implant recipients in relation to electrically evoked stapedius reflex measurements during surgery, and to electrode design, stimulation mode, and T and C levels over a nine month period after surgery. Seventy-five implant recipients, implanted with a Nucleus straight electrode array or a Contour array, were included. The results show that: (1) during surgery electrode impedance decreases markedly after electrically evoked stapedius reflex measurements, (2) after surgery, during the period without stimulation until speech processor switch-on, impedance increases, (3) after processor switch-on impedance decreases. The lower impedance values after a period of stimulation are found at the higher T and C levels. Impedances of the straight array electrodes are lower than those of the Contour array. The difference corresponds mainly to their respective surface areas. In addition, the straight array shows a larger increase of impedance in the apical direction than the Contour array, probably because of the larger fluid environment around the basal electrodes of the straight array.

Sumario

El objetivo de este estudio fue investigar la impedancia de los electrodos en implantados cocleares en relación con medidas de reflejo estapedial evocado eléctricamente durante la cirugía, con el diseño del electrodo, el modo de estimulación, y los niveles T y C durante los 9 meses siguientes a la cirugía. Se incluyeron setenta y cinco sujetos implantados con un electrodo Nucleus recto o con uno Contour. Los resultados muestran que, 1) la impedancia de los electrodos disminuye marcadamente después de las mediciones del reflejo estapedial evocado eléctricamente, durante la cirugía, 2) la impedancia aumenta después de la cirugía, durante el período sin estimulación y hasta la activación de procesador de lenguaje, 3) después de la activación del procesador la impedancia disminuye. Se encontró que los menores valores de impedancia después de un periodo de estimulación se encuentran en los niveles T y C más altos. Las impedancias de los electrodos rectos son más bajas que aquellas del Contour. La diferencia corresponde a sus respectivas áreas de superficie. Además, los electrodos rectos muestran un incremento mayor de la impendacia en la dirección apical que los electrodos Contour, probablemente debida al ambiente con más líquido alrededor de los electrodos basales de los electrodos rectos.     

The nucleus contour electrode array: an electrophysiological study

OBJECTIVE/HYPOTHESIS: Positioning intracochlear electrodes adjacent to the modiolus would lead to a reduction in threshold levels and latencies, as measured with electrically evoked auditory brainstems responses. Recently, Cochlear Corporation introduced a new perimodiolar array (Contour electrode) characterized by a platinum stylet inserted into the array's silicone carrier that keeps the electrode in a straightened configuration before insertion. After completion of the insertion, the withdrawal of the stylet allows the array to coil within the cochlea positioning electrodes closer to the modiolus. The purpose of the study was to analyze the stimulation properties of the Contour electrode by evaluating the effects of the withdrawal of the stylet on electrical auditory brainstem response (EABR) characteristics. METHODS: Electrical auditory brainstem response registrations were performed intraoperatively on three electrodes (1 apical, 1 medial, 1 basal) before and after the removal of the stylet in 10 patients implanted with the Nucleus 24 Contour device. A within-patient comparison of EABR characteristics was performed. The Student test was used to assess differences in EABR measures obtained before and after the stylet removal. RESULTS: Mean EABR thresholds were significantly lower after the removal of the stylet than with the stylet in situ for all three electrodes tested. After the removal of the stylet, latencies of waves III and V significantly decreased, whereas amplitudes significantly increased. CONCLUSION: Reduction in EABR threshold levels and latencies as well as an increase in waves III and V amplitudes after the stylet removal all demonstrate the effectiveness of the Contour system in positioning intracochlear electrodes closer to auditory neurons.     

Changes in psychophysical parameters during the first month of programming the nucleus contour and contour advance cochlear implants

This retrospective study evaluated the psychophysical parameters of 29 postlingually deafened adults who had received a Nucleus Contour or Contour Advance implant during the first month of fitting in order to determine how many sessions were required to obtain a stable implant MAP. The T-levels did not differ significantly across the five fitting sessions, but the C-levels as well as the dynamic range showed an increase up to the fourth session. For all psychophysical parameters the basal, medial and apical portion of the electrode array differed significantly across sessions. Subjects with a Nucleus Contour implant had higher comfortable levels than subjects with a Contour Advance implant. The duration of deafness, presence of preoperative tinnitus, aetiology, frequency of fitting, stimulus rate and number of active channels did not significantly influence the psychophysical levels. These results suggested that four fitting sessions within the first three weeks after switch on should initially suffice and the fifth session could be planned beyond one month.     

Comparison of speech perception performance between the Nucleus 24 and Nucleus 24 Contour cochlear implant systems

OBJECTIVE: To compare the 1-, 3-, and 6-month postoperative speech perception scores obtained by a group of subjects who received the new perimodiolar array (Nucleus Contour) cochlear implant with those obtained by a group of subjects implanted with the straight electrodes of the previous-generation Nucleus 24 device. MATERIAL AND METHODS: The speech performance of 10 postlingually deafened adults implanted with the Nucleus Contour device was compared with that of matched controls who received the Nucleus 24 model. Objective measures included word and sentence speech recognition scores. RESULTS: Patients implanted with the Nucleus Contour device obtained significantly higher word and sentence recognition scores after short-term use of the implant compared to those obtained by patients implanted with the Nucleus 24 model. CONCLUSION: Further long-term studies are required to determine whether the Nucleus Contour CI recipients continue to improve over time.     

Combined electroacoustic stimulation in conventional candidates for cochlear implantation

Objective:To report on combined ipsilateral electrical and acoustic stimulation in a subset of conventional candidates for cochlear implantation where preoperative pure tone thresholds were 85-110 dB HL, 250-500 Hz). In the remaining 7 cases, residual hearing was maintained up to at least 6 months after operation with minor changes. Insertion depth angles in these cases ranged from 285 to 420 degrees . For these subjects, the mean preoperative score for words presented at 65 dB SPL was 22%. Mean postoperative scores were 56% for CI alone, and 68% for CI plus ipsilateral hearing aid (p < 0.05, paired t). For sentences presented in multitalker babble noise at 5 dB SNR, mean scores were 61% CI alone, and 75% CI+IpsiHA (p < 0.01, paired t). Conclusions: Hearing was conserved during surgery and over time in 70% of conventional candidates implanted with the Nucleus 24 Contour Advance CI who had significant levels of preoperative low-frequency residual hearing (相似文献