B细胞淋巴瘤-2蛋白在年龄相关性聋小鼠耳蜗中的表达

目的　了解B 细胞淋巴瘤- 2（B c e l l lymphoma-2,Bcl-2）在不同年龄段年龄相关性小鼠内耳中的表达量及部位的差异,为后续研究Bcl-2信号通路做准备。方法　采用听性脑干反应（ABR）行听力水平测试,耳蜗基底膜铺片行毛细胞形态,数量观察,实时荧光定量、免疫荧光组织化学法和蛋白质印迹分析进行不同年龄段（“年轻”组、“老年”组）C57BL/6小鼠耳蜗Bcl-2在mRNA和蛋白表达水平检测。结果　ABR两组比较,老年组小鼠平均阈值均高于年轻组,各频率差异均有统计学意义。耳蜗基底膜铺片两组比较,老年组耳蜗底转毛细胞排列紊乱且部分缺失,螺旋神经节细胞稀疏,排列凌乱。实时荧光定量结果提示Bcl-2在mRNA水平“老年”鼠耳蜗表达降低。免疫荧光组织化学法和蛋白质印迹分析提示Bcl-2在蛋白水平“老年”鼠耳蜗表达降低,且Bcl-2表达位于胞浆,内毛细胞表达高于外毛细胞。结论　Bcl-2在“老年”鼠耳蜗表达降低,且Bcl-2表达降低与耳蜗毛细胞缺失、听力下降可能具有相关性。     

腱糖蛋白-W在不同发育阶段C57BL/6小鼠耳蜗中的表达

目的研究Tnn基因编码的腱糖蛋白-W(tenascin-W,TN-W)在出生后不同发育阶段小鼠耳蜗内的表达,初步探讨tenascin-W在听觉系统中的功能。方法以出生后(postnatal day,P)1、3、14、28天(P1、P3、P14、P28)各6只及出生后7天(P7)9只C57BL/6小鼠作为研究对象,通过免疫荧光标记观察tenascin-W在耳蜗中的表达及定位,运用实时荧光定量PCR(real-time quantitative PCR,RT-qPCR)检测各发育阶段小鼠耳蜗中Tnn mRNA相对表达水平,Western blot法检测tenascin-W在小鼠耳蜗中的表达。结果免疫荧光标记显示tenascin-W在P1、P3、P7、P14、P28小鼠耳蜗中均有表达。在P1、P3、P7小鼠耳蜗螺旋神经节、Corti器中均有表达,在P14、P28小鼠仅在螺旋神经节高表达,在Corti器中不表达,在各发育阶段小鼠耳蜗血管纹均有表达;共染显示其与Ⅲ型β-tubulin共定位在螺旋神经节神经元胞体的胞浆中。RT-qPCR显示Tnn mRNA在P7小鼠耳蜗相对表达量最高,Western blot法检测到tenascin-W在P7小鼠耳蜗中有表达。结论Tenascin-W在小鼠耳蜗各发育阶段均有表达,在P7表达量最高,且主要定位于螺旋神经节神经元,提示该蛋白可能影响耳蜗螺旋神经元发育及功能,对小鼠正常听觉的维持发挥重要作用。     

Bone conductive implantation in asymmetric hearing loss (AHL)

Abstract

Background: Bone conductive implants (BCI) represent one possible solution for rehabilitation of single-sided deafness (SSD).

Aims: The aim of the present study was to verify the efficacy of bone conduction implantation in subjects with unilateral severe-to-profound hearing loss and contralaterally impaired hearing, that is, asymmetric hearing loss (AHL), and to compare it with known BCI indications for SSD.

Material and methods: Twenty-one subjects received BCI for either SSD or AHL. All of the subjects underwent a battery of audiological and subjective tests, Data were collected and statistically evaluated within and between the SSD group and the AHL group.

Results: A PTA threshold gain was observed in AHL patients along with improved values in speech audiometry in quiet and noise. The two visual analogue scale evaluations (QoL and QoS) and the GBI showed significantly better scores in AHL patients compared to SSD patients.

Conclusions: BCI provided improvement for auditory or speech recognition in AHL subjects, as compare to SSD. From these findings, it is possible to predict a positive role of BCI for some audiological aspects of AHL subjects that are generally not present or not detectable in SSD cases.     

Distribution of pejvakin in human spiral ganglion: An immunohistochemical study

Abstract

Up to 10% of permanent hearing impairments in children originate from lesions in the neuronal auditory pathway. This form of auditory neuron injury called auditory neuropathy features a preservation of outer hair cell integrity but an impaired inner hair cell function and/or neuronal transmission. DFNB59 gene encodes the protein pejvakin (PJVK) and its mutations cause autosomal recessive auditory neuropathy as well as other forms of sensorineural hearing loss. The finding of distinct forms of hearing anomalies was based on studies of consanguineous families from different ethnic groups as well as studies in mice with PJVK gene mutations. In the present immunohistochemical study, the distribution of pejvakin protein in surgically obtained human cochleae was for the first time investigated. The human cochleae had normal hearing thresholds before the operation. The expression of pejvakin was located in the cell bodies of all spiral ganglion neurons rather than the nerve fibers that were labeled with Tuj 1 antibody. As Tuj 1 antibody stained the cytoplasm of Type 1 cells, pejvakin antibody labeled both type 1 and type 2 cells. The nuclei of the neurons were also PJVK-positive. No labeling was seen in the structures within the organ of Corti and the stria vascularis. In the previous study, PJVK had been detected in the hair cells, the spiral ganglion, the cochlear nuclei, the superior olivary nucleus, and the inferior colliculus in mouse. Our study demonstrated for the first time the expression of PJVK in human spiral ganglion neurons. Its functional role in neural signal propagation and synchrony needs further elucidation.     

Role of reactive radicals in degeneration of the auditory system of mice following cisplatin treatment

Objective—It has been suggested that reactive radical species are involved in the mechanism of cisplatin-induced hearing loss. However, the nature of the free radicals involved is not fully understood. We examined the effects of two highly reactive species, hydroxyl radicals and peroxynitrite, on the auditory system of mice following cisplatin treatment.

Material and Methods—Expression of 4-hydroxynonenal (HNE), a marker of lipid peroxidation by the hydroxyl radical, and nitrotyrosine (NT), a marker for protein peroxidation by peroxynitrite, was examined immunohistochemically in mouse cochleae injured by means of local application of cisplatin.

Results—Loss of outer hair cells (OHCs) and spiral ganglia was found in cochleae affected by cisplatin. Both HNE and NT were detected in auditory epithelia and neurons damaged by cisplatin. Interestingly, auditory hair cells produced HNE, but not NT. Our findings indicate contributions by both HNE and NT to the degeneration of the auditory system due to cisplatin, and a crucial role of the hydroxyl radical in degeneration of OHCs.

Conclusion—The hydroxyl radical may be a critical target for a strategy aimed at protecting auditory function from cisplatin toxicity.     

Genetic background effects on age-related hearing loss associated with Cdh23 variants in mice

Inbred strain variants of the Cdh23 gene have been shown to influence the onset and progression of age-related hearing loss (AHL) in mice. In linkage backcrosses, the recessive Cdh23 allele (ahl) of the C57BL/6J strain, when homozygous, confers increased susceptibility to AHL, while the dominant allele (Ahl+) of the CBA/CaJ strain confers resistance. To determine the isolated effects of these alleles on different strain backgrounds, we produced the reciprocal congenic strains B6.CBACa-Cdh23^Ahl+ and CBACa.B6-Cdh23^ahl and tested 15-30 mice from each for hearing loss progression. ABR thresholds for 8 kHz, 16 kHz, and 32 kHz pure-tone stimuli were measured at 3, 6, 9, 12, 15 and 18 months of age and compared with age-matched mice of the C57BL/6J and CBA/CaJ parental strains. Mice of the C57BL/6N strain, which is the source of embryonic stem cells for the large International Knockout Mouse Consortium, were also tested for comparisons with C57BL/6J mice. Mice of the C57BL/6J and C57BL/6N strains exhibited identical hearing loss profiles: their 32 kHz ABR thresholds were significantly higher than those of CBA/CaJ and congenic strain mice by 6 months of age, and their 16 kHz thresholds were significantly higher by 12 months. Thresholds of the CBA/CaJ, the B6.CBACa-Cdh23^Ahl+, and the CBACa.B6-Cdh23^ahl strain mice differed little from one another and only slightly increased throughout the 18-month test period. Hearing loss, which corresponded well with cochlear hair cell loss, was most profound in the C57BL/6J and C57BL/6NJ strains. These results indicate that the CBA/CaJ-derived Cdh23^Ahl+ allele dramatically lessens hearing loss and hair cell death in an otherwise C57BL/6J genetic background, but that the C57BL/6J-derived Cdh23^ahl allele has little effect on hearing loss in an otherwise CBA/CaJ background. We conclude that although Cdh23^ahl homozygosity is necessary, it is not by itself sufficient to account for the accelerated hearing loss of C57BL/6J mice.     

Age-Related Changes in Cochlear Endolymphatic Potassium and Potential in CD-1 and CBA/CaJ Mice

The CD-1 mouse strain is known to have early onset of hearing loss that is progressive with aging. We sought to determine whether a disturbance of K⁺ homeostasis and pathological changes in the cochlear lateral wall were involved in the age-related hearing loss (AHL) of CD-1 as compared to the CBA/CaJ strain which has minimal AHL. In the present study, the endocochlear potential (EP) and endolymphatic K⁺ concentration ([K⁺]_e) were measured in both strains of mice with double-barrel microelectrodes at young (1–2 mo) and old (5–9 mo) ages. CBA/CaJ mice displayed no changes with aging in EP and [K⁺]_e of the basal turn. In the apical turn, there was a small positive shift of the EP (10 mV) with aging under both normoxic and acute anoxic conditions (–EP), without any change of [K⁺]_e. Further, there were no obvious pathological changes in the lateral wall of CBA/CaJ mice. By contrast, old CD-1 mice displayed a significantly reduced [K⁺]_e by 30% in both basal and apical turns with no significant changes in normoxic EP. The –EP in the apical turn was significantly reduced in magnitude by 6 mV. A severe loss of cells with aging was observed in the region of type IV fibrocytes of the apical and basal turns and of type II fibrocytes in the basal turn. A complete degeneration of organ of Corti was also observed at the basal turn of old CD-1 mice, as well as a basalward decline of spiral ganglion neuron density. The pathological changes in spiral ligament of CD-1 mice were similar to those of an inbred mouse strain C57BL/6J that expresses an AHL gene (ahl) and might be a primary etiology of AHL of CD-1 mice. These findings have ramifications for our understanding of AHL and for interpretation of genetic mutations in a CD-1 background.     

Lower Dose of Aminoglycoside Ototoxic Exposure Causes Presynaptic Alterations Assoicated with Hearing Loss

Objective To study presynaptic alternations of cochlear ribbons arising from aminoglycoside ototoxic stimuli in C57BL/6J mice. Methods Animals were injected with low dose gentamicin (100 mg/kg/day) for 14 days, From the 14th to 28th days, the mice were maintained free of gentamicin treatment. Immunohisto-chemistry labeling was employed to trace RIBEYE, a major presynaptic componment of ribbon synapses. RIBEYE/CtBP2 expression levels were assessed and compared with hearing threshold shifts. Auditory func-tion was assessed by auditory brainstem responses. The stereocilia of outer hair cells (OHCs) and IHCs was examined by scanning electron microscopy (SEM). Results Hearing thresholds were elevated with peak hearing loss observed on the 7th day after gentamicin exposure, followed by improvement after the 7th day. RIBEYE/CtBP2 expression directly correlated with observed hearing threshold shifts. Strikingly, we did not see any obvious changes in stereocilia in both OHCs and IHCs until the 28th day. Mild changes in stereocil-ia were only observed in OHCs on the 28th day. Conclusions These findings indicate that presynapse co-chlear ribbons, rather than stereocilia, may be sensitive to aminoglycoside ototoxic exposure in mice cochle-ae. A pattern of RIBEYE/CtBP2 expression changes seems to parallel hearing threshold shifts and suggests presynaptic response properties to lower dosage of aminoglycoside ototoxic stimuli.     

Degeneration of stria vascularis in age-related hearing loss; a corrosion cast study in a mouse model

Conclusion With age, in a mouse model, degenerative changes to the capillaries of the stria vascularis are observed. These range from a narrowing of vessel lumen to complete degeneration of strial vessels. Other vascular beds in the cochlea are relatively unchanged with age. Strial capillaries at the cochlear base are significantly more affected than those in mid-apical turns.

Objectives Previous work suggests that age-related hearing loss is associated with degenerative changes to cochlear vasculature; the term strial presbyacusis is often cited. This study reports on vascular changes observed in a murine model of presbyacusis, analyzed using corrosion cast techniques.

Methods A novel corrosion cast technique was developed to compare cochlear vasculature in control mice (non-presbycusic, CD1) and old (>?6 months) C57BL/6 animals. ABR measures indicated a significant age-related threshold elevation in the C57BL/6 mice. Cochlear vascular casts were imaged using scanning electron microscopy, and vessel degeneration was quantified by measuring capillary diameters.

Results Corrosion casts of cochlear vasculature in 6–12 month old C57BL/6 mice reveal significant degeneration of stria vascularis. Other capillary beds (spiral ligament and the spiral limbus) appear unchanged. Comparison of strial capillary diameters reveals significantly more damage in basal/lower-turn regions compared with the cochlear mid-turn.     

A study of hearing function and histopathologic changes in the cochlea of the type 2 diabetes model Tsumura Suzuki obese diabetes mouse

Objectives: This study used Tsumura Suzuki Obese Diabetes (TSOD) mice as a spontaneous type 2 diabetes model and Tsumura Suzuki Non-obesity (TSNO) mice as controls to investigate factors involved in the onset of hearing impairment.

Method: Body weight, blood glucose levels, and auditory brainstem responses (ABRs) were measured. The cochleae were excised and evaluated histopathologically.

Results: The TSOD mice showed significant hyperglycemia at 2–7 months and severe obesity at 5–10 months; significantly elevated ABR thresholds at 8–10 months; and the capillary lumens in the cochlea stria vascularis were narrower in the TSOD mice than in the TSNO mice. At 17 months, India ink vascular staining of the TSOD mice’s cochleae revealed decreased capillary density in the stria vascularis. The vascular area of capillaries in the stria vascularis and the vascular area were significantly smaller in TSOD mice. Histopathological analysis showed vessel wall thickening in the modiolus and narrowed capillaries in the stria vascularis, suggesting reduced blood flow to the inner ear.

Conclusion: The diabetes mice model used in our study showed early age-associated hearing loss, and histopathology showed findings of vessel wall thickening in the modiolus, narrowing of capillaries in the stria vascularis, and chronically reduced blood flow in the cochlea.     

Extended use of systemic steroid is beneficial in preserving hearing in guinea pigs after cochlear implant

Conclusion: Seven-day administration of systemic steroids was more effective in preserving hearing for 12 weeks after cochlear implantation (CI) than a 3-day delivery.

Objectives: To determine the effectiveness of extended delivery of systemic steroids to preserve hearing in guinea pigs after CI.

Methods: Dexamethasone (4?mg/ml) was delivered parenterally via a mini-osmotic pump for either 3 or 7 days. A dummy CI electrode was inserted via cochleostomy approach in 8-week-old guinea pigs. Auditory thresholds were assessed from tone burst auditory brainstem responses (2, 8, 16, 24, and 32?kHz) at 1?day prior to CI, and 1, 4, and 12 weeks after implantation. Histologic evaluation of the cochleae was carried out.

Results: No differences were observed in hearing thresholds among groups before CI. Significant hearing preservation was achieved at 8, 16, 24, and 32?kHz only in the 7-day infusion group compared with the control group at 1 week after CI. The same trend was maintained at 4 weeks (16, 24?kHz) and 12 weeks (16, 24, and 32?kHz). Histologic review of the 7-day infusion group revealed less fibrosis and ossification in the scala tympani and the preservation of more spiral ganglion cells, compared with the control group.     

Etiology of single-sided deafness and asymmetrical hearing loss

Abstract

Conclusions: The present study revealed that various etiologies are involved in single-sided deafness (SSD), and that the cause of SSD and asymmetrical hearing loss (AHL) differed greatly between congenital/early-onset cases and adult cases. Clarification of the etiology is the first step toward providing appropriate intervention.

Objectives: The study aimed to clarify the etiology of SSD and AHL patients.

Methods: The etiology of a total of 527 SSD or AHL patients who visited Shinshu University Hospital between 2006 and 2016 were analyzed by imaging as well as serological tests for mumps virus, and CMV DNA testing.

Results: In our cohort of congenital/early-onset SSD (n?=?210), the most prevalent cause in children was cochlear nerve deficiency (43.7%; 87 of 199 patients undergoing CT and/or MRI), followed by CMV infection, mumps infection, anomalies of the inner ear, ANSD, and other rare etiologies. In contrast, half of the adult SSD patients presented with idiopathic sensorineural hearing loss, followed by various types of otitis media, cerebellopontine angle tumor and other rare etiologies.     

Localization of melatonin and its receptors (melatonin 1a and 1b receptors) in the mouse inner ear

Abstract

Background: In the inner ear, evidence has been gathered indicating that melatonin plays important roles in inner ear physiology and pathophysiology. However, no attempt has been made previously to investigate the localization or expression of melatonin and its receptors in the whole inner ear.

Aims/objectives: To analyze the presence of melatonin and its receptors in the normal mouse inner ear.

Material and methods: C57BL6/J mice were used in this study. The localizations of melatonin, MT1a and MT1b in the inner ear, i.e. cochlea, vestibular end organs, vestibular ganglion and endolymphatic sac (ES), were studied by immunohistochemistry.

Results: The organ of Corti, spiral ganglion, vestibular ganglion, vestibular sensory cells, vestibular dark and transitional cells, and ES epithelial cells showed an immunofluorescence reaction to melatonin, MT1a and MT1b.

Conclusion and significance: The present findings show that melatonin and its receptors (MT1a and MT1b) are present in the inner ear, thus supporting the hypothesis that melatonin plays a physiological role in the inner ear.     

Development of a safe dexamethasone-eluting electrode array for cochlear implantation

Abstract

Objectives

Cochlear implantation can result in trauma leading to increased tissue response and loss of residual hearing. A single intratympanic application of the corticosteroid dexamethasone is sometimes used clinically during surgery to combat the potential effect of trauma on residual hearing. This project looked at the safety and efficacy of dexamethasone eluted from an intracochlear array in vivo.

Methods

Three trials were conducted using normal hearing adult guinea pigs implanted with successive iterations of dexamethasone-eluting (DX1, DX2, and DX3) or non-eluting (control) intracochlear electrode arrays. The experimental period for each animal was 90 days during which hearing tests were performed at multiple time points.

Results

There was no significant difference between matched control array and dexamethasone array groups in terms of spiral ganglion neuron density, organ of Corti condition, or fibrosis and ossification. A cochleostomy seal was present in all implanted cochleae. There were no differences in the degree of hearing threshold shifts between DX1 and DX3 and their respective control arrays. Cochleae implanted with DX2 arrays showed less hearing loss and marginally better spiral ganglion neuron survival than their control array counterparts. Post-explant inspection of the DX2 and DX3 arrays revealed a difference in pore density following dexamethasone elution.

Conclusion

The dexamethasone doses used were safe in the guinea pig cochlea. Dexamethasone did not inhibit formation of a cochleostomy seal. The level of hearing protection afforded by dexamethasone eluting from an intracochlear array may depend upon the degree of elution and level of trauma inflicted.     

DR5在GJB2基因条件敲除小鼠耳蜗表达分布及年龄相关性变化

目的研究GJB2基因条件敲除（cCx26Pax2Cre）小鼠耳蜗DR5表达情况，探讨GJB2基因突变导致耳聋的机制。方法 cCx26Pax2Cre小鼠为实验组，BALB/C小鼠为对照组，分别取P8、P12和P21时小鼠耳蜗行冰冻切片，利用荧光标记免疫组织化学方法和激光共聚焦显微镜技术观察死亡受体5（death receptor，DR5）蛋白在耳蜗的表达情况，用Image Pro Plus 6.0计算平均光密度值，SPSS 18.0进行统计分析。结果 P8时DR5主要表达在柯蒂氏器外侧的支持细胞、耳蜗外侧壁Ⅱ型纤维细胞、盖膜，随着日龄的增加，表达逐渐向内侧延伸到内侧支持细胞，P12和P21时还出现了螺旋缘、毛细胞、螺旋神经节细胞、螺旋凸DR5表达阳性，而且表达强度随日龄增加而逐渐变强。在野生小鼠DR5也有表达但较弱。与野生型小鼠相比， cCx26Pax2Cre小鼠耳蜗蜗轴螺旋管内神经纤维DR5表达的光密度值明显增大，经统计学分析两者具有显著性差异（P＆lt;0.05）。结论 cCx26Pax2Cre小鼠缝隙连接功能异常，可能导致耳蜗细胞出现葡萄糖短缺，导致三磷酸腺苷（adenosine-triphosphate， ATP）不足，引起DR5的表达上调，直接激活凋亡的死亡受体途径，或间接激活线粒体通路使凋亡信号进一步放大，导致耳蜗细胞凋亡的发生，最终引起cCx26Pax2Cre小鼠听力下降。     

Three-Dimensional Distribution of Cochlear Macrophages in the Lateral Wall of Cleared Cochlea

Objectives Resident macrophages are well known to be present in the cochlea, but the exact patterns thereof in spiral ligaments have not been discussed in previous studies. We sought to document the distribution of macrophages in intact cochleae using three-dimensional imaging.Methods Cochleae were obtained from C-X3-C motif chemokine receptor 1^+/GFP mice, and organ clearing was performed. Three-dimensional images of cleared intact cochleae were reconstructed using two-photon microscopy. The locations of individual macrophages were investigated using 100-μm stacked images to reduce bias. Cochlear inflammation was then induced by lipopolysaccharide (LPS) inoculation into the middle ear through the tympanic membrane. Four days after inoculation, three-dimensional images were obtained.Results Macrophages were scarce in areas adjacent to the stria vascularis, particularly the area just beneath it even though many have suspected macrophages to be abundant in this area. This finding remained consistent upon LPS-induced cochlear inflammation, despite a significant increase in the number of macrophages, compared to non-treated cochlea.Conclusion Resident macrophages in spiral ligaments are scarce in areas adjacent to the stria vascularis.     

Immunohistological analysis of neurturin and its receptors in human cochlea

ObjectiveDifficulties in obtaining properly preserved human cochlea have been a major obstacle to in vitro study of this deeply located and hard bone-fortressed hearing organ. Our study aimed at investigating GDNF family ligands (GFLs) and their receptors in the human cochleae that were surgically obtained during a transcochlear approach dealing with life-threatening, intra-cranial meningiomas.MethodsThe specimens were properly fixed with 4% paraformaldehyde in the operating room. By using immunohistochemical techniques, distribution of GDNF, Neurturin (NTN, one member of GFLs), as well as cRet, GFRα-1 and GFRα-2 receptors in the human cochleae was investigated. Five cochleae from five adult patients were processed for the study. The patients had normal hearing threshold before operation.ResultscRet receptor immunoreactivity was seen in the spiral ganglion neurons, mainly inside the cell bodies but rarely in the nerve fibers and not in the organ of Corti. Immunolabeling for GFRα-1 and GFRα-2 receptors was identified mainly in the cell bodies of the spiral neurons than in the nerve fibers. In the organ of Corti, GFRα-1 immunostaining could be demonstrated in the Deiters’ cells, Hensen cells, inner pillar cells, and weakly in the inner hair cells but not in the outer hair cells; no structures in the organ of Corti were labeled with GFRα-2 receptor antibody. NTN immunostaining was found in the supporting cells of organ of Corti, including Deiters’ cells, Hensen cells as well as Claudius’ cells. In the spiral ganglia, NTN immunostaining was seen in both the cell bodies and the nerve fibers of neurons. GDNF immunoreactivity was not revealed in human cochlea.ConclusionSurgically obtained human cochleae were properly fixed and underwent immunohistochemical investigation of neurotrophic elements. NTN and its receptors discovered in current study can be responsible for the unique neuronal survival properties in human spiral ganglion (hSG); a prerequisite for the function of cochlear implants.     

Binaural advantages in using a cochlear implant for adults with profound unilateral hearing loss

Background: Recent studies of cochlear implants (CIs) in profound unilateral hearing loss (UHL) patients have demonstrated a restoration of some binaural hearing.

Aims/Objectives: The objective was to evaluate three possible advantages of binaural hearing in CIs adult users with UHL including single-side deafness (SSD) and asymmetric hearing loss (AHL) subgroups.

Material and methods: A prospective study was conducted that included 70 sequentially implanted patients. Subgroups of these subjects included 64 with a postlingual onset of a profound hearing loss on the implanted side and 6 with a prelingual onset of that loss. Three binaural effects – redundancy, head shadow, and squelch – were evaluated.

Results: Significant differences between the ‘CI on’ and ‘CI off’ conditions were found for all three binaural effects for the study group as a whole and for the postlingual subgroup. However, results for the subjects in the prelingual subgroup did not demonstrate any of the binaural advantages.

Conclusion and significance: Patients with a postlingual onset of a profound hearing loss in one ear and normal hearing or only a moderate loss in the other ear are able to make the effective use of a CI in the profound-loss ear in conjunction with acoustic stimulation of the other ear.