耳蜗钾循环中Na-K-2Cl与听觉生理关系的研究进展

耳蜗钾循环对维持正常听觉生理功能具有重要作用.耳蜗钾循环途径中涉及诸多离子通道,本文就其中的Na-K-2Cl联合转运子(NKCC)-1与听觉生理关系的研究进展综述如下.     

检测听觉神经通路客观方法的回顾

用于评估耳蜗到皮层听觉神经通路功能的客观生理方法包括耳声发射 ( OAEs)、听觉诱发电位和听觉传出神经反射等。中耳肌反射 ( MEMR)和橄榄耳蜗反射( OCR)是评估人听觉系统功能的两个传出神经反射 ,可反映位听神经听觉分支到低位脑干听觉神经通路的活动 ,当听神经或低位脑干发生病变时 ,MEMR与OCR出现异常反应。虽然 MEMR已成为检测影响听觉神经通路完整性的第 颅神经占位性病变或听神经病变的常用方法 ,但易受中耳疾病与 Bell麻痹的干扰 ,因此 MEMR在评估听神经功能方面受到一定限制。耳声发射传出抑制则反映橄榄耳蜗束到外毛…     

内、外侧橄榄耳蜗束的分离及其对耳蜗功能的影响

听觉传出神经通路是听觉系统重要的投射体系之一,而橄榄耳蜗束(olivocochlear bundle,OCB)是唯一已被证实的听觉传出神经通路,包括内侧橄榄耳蜗束(medial olivocochlear,MOC)和外侧橄榄耳蜗束(lateral olive cochlear,LOC)两部分。近年来,许多学者试图用电刺激、解剖学分离和药理学分离     

不同植入年龄和植入后时间的EMLR反应特点研究

目的利用电诱发中潜伏期反应(Electrically evoked middle latency response,EMLR)对语前聋人工耳蜗植入患儿进行听觉功能评估,了解人工耳蜗植入年龄对听觉功能的影响,研究语前聋患儿人工耳蜗植入后听觉功能的变化规律。为人工耳蜗植入时间的选择及植入后听觉康复训练计划的制定提供理论依据。方法本研究共有42例语前聋患儿参与,按植入年龄将患儿分为2组,植入年龄小于3岁的患儿28例,大于3岁的患儿14例,平均植入后时间为(15.06±15.53)月。按人工耳蜗植入后时间将患儿分为4组,植入后小于6个月的患儿12例,6~12个月的患儿16例,12~24个月的患儿4例,大于24个月的患儿10例,平均植入年龄为(2.98±1.64)岁。分别对各组病人进行EMLR的检测,并对结果进行统计分析。结果42例语前聋人工耳蜗植入患儿中共有38例检出EMLR,总检出率为90.48%。3岁以内进行人工耳蜗植入患儿的Pa Nb平均波间振幅(2.34±1.26)μV,3岁以后进行植入患儿的平均Pa Nb波间振幅(1.48±0.49)μV,两组间存在显著差异,p<0.05。人工耳蜗植入后6~12个月患儿的Pa波潜伏期为(30.52±0.85)ms,人工耳蜗植入后24个月以上患儿的Pa波潜伏期为(25.98±1.80)ms,两组间存在显著差异,p<0.05。结论植入年龄和植入后时间是语前聋儿童人工耳蜗植入后听觉功能的重要影响因素。语前聋患儿3岁以内植入人工耳蜗患儿的听觉功能明显优于3岁以上植入的患儿。语前聋患儿的听觉功能在人工耳蜗植入后的两年内处于快速变化期,此时期内进行康复训练患儿可获得较好的听觉功能。     

KCNQ1在小鼠耳蜗血管纹的表达及在听觉中的意义

目的探讨KCNQ1在耳蜗侧壁血管纹的表达及其在听觉中的作用。方法以不同基因型小鼠KC-NQ1-/-(突变纯合子)、KCNQ1 /-(杂合子)和KCNQ1 / (野生型)以及C57BL/6J小鼠为实验对象,采用免疫组织化学和ABR检测技术,检测KCNQ1在小鼠耳蜗血管纹的表达及其听力。结果KCNQ1蛋白阳性颗粒集中在小鼠耳蜗血管纹边缘细胞顶膜。KCNQ1 / 小鼠的听力正常,短声ABR的阈值为36.67±7.13dBSPL;KCNQ1 /-小鼠听力低于同窝KCNQ1 / 野生型鼠,短声ABR的阈值为38.25±9.35dB SPL;KCNQ1-/-小鼠呈现全聋,ABR在100dB SPL时仍无反应。结论KCNQ1是位于耳蜗侧壁血管纹边缘细胞的重要通道蛋白,在维系耳蜗听觉功能中有重要作用。KCNQ1通道蛋白的缺失或功能受限可以不同程度地影响耳蜗的听觉功能。     

人工听觉的过去现在和未来

电诱发人工听觉(简称人工听觉)通过电刺激听觉神经来恢复、提高或重建人的听觉功能。电刺激听神经包括早期使用的单电极及目前使用的多电极人工耳蜗植入,以及结合低频残存声听觉的短电极耳蜗植入。人工耳蜗植入的工作原理是绕过已损伤的毛细胞,直接由刺激残存的听神经纤维     

听觉脑干植入

听觉脑干植入(ABI)是人工耳蜗植入技术的一种进展,其工作原理与人工耳蜗类似,不同的是人工耳蜗通过电极刺激耳蜗内的听神经纤维而获得听觉,而ABI是将电极越过耳蜗和听神经直接刺激脑干耳蜗核复合体的听神经元产生听觉.就ABI的适应证及禁忌证、手术入路及手术方法、手术并发症以及植入后听力改善的效果等方面进行概述.     

人工耳蜗植入的手术技术

前言 人工耳蜗的作用是刺激听神经,在大脑形成听觉信号。使用这种技术的前提是听觉神经的通路是完整的。已经失去功能的耳蜗用于安放刺激电极(图1,2)。     

大鼠耳蜗发育过程中突触素的表达差异

目的 研究大鼠耳蜗发育过程中突触素(synaptophysin,SYN)的表达差异,探讨SYN表达与听觉功能发育成熟的关系及耳蜗中三磷酸腺苷(adenosine triphosphate,ATP)的来源.方法 选取健康SD大鼠25只,按出生后天数将其分为出生后1、5、10、14、28天组(即:P1、P5、P10、P14和P28组),每组5只,运用免疫组化的方法比较各组大鼠耳蜗中SYN的表达差异.结果 P1、P5和P10组大鼠顶回的Corti器、Kolliker器未发现SYN表达;P10组底回及蜗管中段、P14组和P28组Corti器的内、外螺旋束、Deiters细胞内侧缘有特异性表达;各组大鼠耳蜗螺旋神经元(spiral ganglion neuron,SGN)胞浆中均有SYN表达.结论 大鼠耳蜗发育过程中SYN的表达存在差异,这种差异有利于神经末梢和靶细胞间构型建立,对听觉系统发育中形成正确的听觉信息编码可能起着关键作用.毛细胞、支持细胞中的ATP可能以非囊泡或以非SYN特异性染色的囊泡形式储存.     

神经生长因子在豚鼠耳蜗中的分布及其意义

目的观察神经生长因子(nerve growthfactor,NGF)在正常豚鼠耳蜗中的定位分布,为进一步研究其在听觉通路中的作用机制提供依据。方法健康杂色豚鼠20只,制备耳蜗石蜡切片,用兔抗小鼠神经生长因子多克隆抗体行免疫组织化学染色(SP法),检测NGF在耳蜗中的表达。结果在正常豚鼠耳蜗中,NGF在螺旋神经节细胞、内外毛细胞、支持细胞、听觉神经纤维中均有表达,细胞内定位主要在胞浆。结论NGF在听觉感受器和听觉通路中有分布,表明在听觉功能的维持中起着一定的作用。     

Electrophysiologic Assessment of Auditory Training Benefits in Older Adults

Older adults often exhibit speech perception deficits in difficult listening environments. At present, hearing aids or cochlear implants are the main options for therapeutic remediation; however, they only address audibility and do not compensate for central processing changes that may accompany aging and hearing loss or declines in cognitive function. It is unknown whether long-term hearing aid or cochlear implant use can restore changes in central encoding of temporal and spectral components of speech or improve cognitive function. Therefore, consideration should be given to auditory/cognitive training that targets auditory processing and cognitive declines, taking advantage of the plastic nature of the central auditory system. The demonstration of treatment efficacy is an important component of any training strategy. Electrophysiologic measures can be used to assess training-related benefits. This article will review the evidence for neuroplasticity in the auditory system and the use of evoked potentials to document treatment efficacy.     

A Dominantly Inherited Progressive Deafness Affecting Distal Auditory Nerve and Hair Cells

We have studied 72 members belonging to a large kindred with a hearing disorder inherited in an autosomal dominant pattern. We used audiological, physiological, and psychoacoustic measures to characterize the hearing disorders. The initial phenotypic features of the hearing loss are of an auditory neuropathy (AN) with abnormal auditory nerve and brainstem responses (ABRs) and normal outer hair cell functions [otoacoustic emissions (OAEs) and cochlear microphonics (CMs)]. Psychoacoustic studies revealed profound abnormalities of auditory temporal processes (gap detection, amplitude modulation detection, speech discrimination) and frequency processes (difference limens) beyond that seen in hearing impairment accompanying cochlear sensory disorders. The hearing loss progresses over 10–20 years to also involve outer hair cells, producing a profound sensorineural hearing loss with absent ABRs and OAEs. Affected family members do not have evidence of other cranial or peripheral neuropathies. There was a marked improvement of auditory functions in three affected family members studied after cochlear implantation with return of electrically evoked auditory brainstem responses (EABRs), auditory temporal processes, and speech recognition. These findings are compatible with a distal auditory nerve disorder affecting one or all of the components in the auditory periphery including terminal auditory nerve dendrites, inner hair cells, and the synapses between inner hair cells and auditory nerve. There is relative sparing of auditory ganglion cells and their axons.     

Relative contributions of auditory and cognitive functions on speech recognition in quiet and in noise among older adults

IntroductionHearing acuity, central auditory processing and cognition contribute to the speech recognition difficulty experienced by older adults. Therefore, quantifying the contribution of these factors on speech recognition problem is important in order to formulate a holistic and effective rehabilitation.ObjectiveTo examine the relative contributions of auditory functioning and cognition status to speech recognition in quiet and in noise.MethodsWe measured speech recognition in quiet and in composite noise using the Malay Hearing in noise test on 72 native Malay speakers (60–82 years) older adults with normal to mild hearing loss. Auditory function included pure tone audiogram, gaps-in-noise, and dichotic digit tests. Cognitive function was assessed using the Malay Montreal cognitive assessment.ResultsLinear regression analyses using backward elimination technique revealed that had the better ear four frequency average (0.5–4 kHz) (4FA), high frequency average and Malay Montreal cognitive assessment attributed to speech perception in quiet (total r² = 0.499). On the other hand, high frequency average, Malay Montreal cognitive assessment and dichotic digit tests contributed significantly to speech recognition in noise (total r² = 0.307). Whereas the better ear high frequency average primarily measured the speech recognition in quiet, the speech recognition in noise was mainly measured by cognitive function.ConclusionsThese findings highlight the fact that besides hearing sensitivity, cognition plays an important role in speech recognition ability among older adults, especially in noisy environments. Therefore, in addition to hearing aids, rehabilitation, which trains cognition, may have a role in improving speech recognition in noise ability of older adults.     

Otoakustische Emissionen, Hirnstammpotentiale, Tonschwellengehör und Sprachverständlichkeit bei auditorischer Neuropathie

The combined findings of "normal evoked otoacoustic emissions (EOAE) and absent or markedly disturbed auditory evoked potentials from the brainstem and/or cortex" has been named auditory neuropathy in the English literature. The pure tone thresholds in these patients range from mild to severe loss. The loss of speech comprehension is out of proportion in comparison to the pure tone threshold elevation. This combination of findings suggests that cochlear function and in particular outer hair cell function, is normal in these patients but also suggests that the inner hair cell / VIII nerve functional unit is abnormal. Disruption in neural synchrony has previously been postulated as a reasonable explanation for the absent auditory brainstem response while otoacoustic emissions are preserved. Because the long-latency auditory evoked potentials, not having the stringent synchrony requirements of the ABR, may also be missing, the term synchrony - disruption may be somewhat misleading. The literature about auditory neuropathy is reviewed here: We now know that a set of salient features distinguishes these patients from the majority of patients with sensorineural hearing loss or other described syndromes. The symptoms defining auditory neuropathy are mild, moderate or severe elevation of auditory thresholds to pure tone stimuli by air and bone conduction, absent to severely abnormal ABRs to high level stimuli, present otoacoustic emissions (that do not suppress with contralateral noise), word recognition ability poorer than expected from the pure tone hearing loss configuration (in cases with mild to moderate hearing threshold elevation) and absent acoustic reflexes to both ipsilateral and contralateral tones. The entire set of findings, consistently seen in these patients, supports the importance of the crosscheck principle in diagnostic evaluation especially in children with delayed and/or impaired language acquisition. It is of ponderous importance that this disorder is not being confused with sensory hearing loss.     

Cognitive function in relation to hearing aid use

Two experiments were conducted to investigate possible relationships between cognitive function and hearing aid use. In Experiment 1, 72 first-time hearing aid users were tested for speech recognition in noise (Hagerman sentence test) with and without hearing aids. Cognitive function was assessed by tests of working memory (reading span test) and verbal information-processing speed. The results indicate that, after controlling for age and hearing loss, significant correlations exist between the measures of cognitive performance and speech recognition in noise, both with and without hearing aids. High cognitive performance was associated with high performance in the speech recognition task. In Experiment 2, 17 first-time hearing aid users with either high or low working-memory capacity tested an experimental hearing aid which processed the sound differently depending on whether or not speech was detected. The results revealed that those with high working-memory capacity were better than those with low capacity at identifying and reporting the specific processing effects of the aid. This may have implications for how reported results should be interpreted in a research context, how a person's rehabilitation needs are formulated, and how hearing aid controls should be supervised. In conclusion, careful attention should be paid to the cognitive status of listeners, as it can have a significant influence on their ability to utilize their hearing aids.     

Auditory neuropathy in childhood

The combination of transient otoacoustic emissions (TOAE) and auditory brainstem responses (ABR) permits us to identify a group of patients with auditory neuropathy. The clinical and therapeutic aspects of these patients are a challenge for otological practice. The patients underwent ENT, neurological, and otological examination using audiometry, tympanometry, stapedial reflex, OAE, or ABR, depending on the patient. TOAE and tympanograms were normal in all cases. The stapedial reflex and ABR were absent in all cases. Logoaudiometry showed a disproportionate decrease in speech comprehension in relation to each patient's audiogram. These audiograms revealed mild-to-moderate hearing loss. These findings suggest that the lesion is sensorineural with normal function of the external hair cells. However, we could not determine if the lesion lay in the internal hair cells, the eighth cranial nerves, or both sites. The causes of hearing loss were: hyperbilirubinemia, perinatal asphyxia, or idiopathic. All the patients were treated by a speech therapist: The results obtained with hearing aids vary. Successful speech rehabilitation depends on early treatment.     

Improving speech audibility with wide dynamic range compression in listeners with severe sensorineural loss

OBJECTIVE: In contrast to fitting strategies for linear amplification, which have been refined frequently for listeners with different degrees of hearing loss, we know relatively little about the effects of wide dynamic range compression (WDRC) amplification for listeners with severe auditory thresholds. The primary objective of this study was to determine if increases in audibility with WDRC amplification improved speech recognition to a comparable degree for listeners with different degrees of hearing loss. DESIGN: Listeners with mild to moderate or severe sensorineural loss were tested on recognition of vowel-consonant-vowel (VCV) syllables and sentences digitally processed with linear and WDRC amplification. The speech materials were presented under conditions of controlled audibility, in which WDRC amplification improved speech audibility over linear amplification. Presentation levels were chosen to provide equivalent increases in audibility with WDRC amplification for both listener groups. A control condition in which audibility was equated for the two amplification conditions was also included. RESULTS: Recognition results for VCV stimuli indicated that both listener groups received the same benefit from the improved audibility provided by WDRC amplification. Results for sentence recognition showed a greater benefit of WDRC amplification for listeners with mild to moderate than for listeners with severe loss. CONCLUSIONS: Increasing the amount of audible speech information with WDRC has similar effects on consonant recognition for listeners with different degrees of hearing loss. Differences in sentence recognition for listeners with different degrees of loss may be due to processing effects or to differences in available acoustic information for longer segments of WDRC-amplified speech.     

Assessing variability in audiovisual speech integration skills using capacity and accuracy measures

Abstract

Objective: While most normal-hearing listeners rely on the auditory modality to obtain speech information, research has demonstrated the importance that non-auditory modalities have on language recognition during face-to-face communication. The efficient utilization of the visual modality becomes increasingly important in difficult listening conditions, and especially for older and hearing-impaired listeners with sensory or cognitive decline. First, this report will quantify audiovisual integration skills using a recently developed capacity measure that incorporates speed and accuracy. Second, to investigate sensory factors contributing to integration ability, high and low-frequency hearing thresholds will be correlated with capacity, as well as gain measures from sentence recognition. Design: Integration scores were obtained from a within-subjects design using an open-set sentence speech recognition experiment and a closed set speeded-word classification experiment, designed to examine integration (i.e. capacity). Study sample: A sample of 44 adult listeners without a self-reported history of hearing-loss was recruited. Results: Results demonstrated a significant relationship between measures of audiovisual integration and hearing thresholds. Conclusions: Our data indicated that a listener's ability to integrate auditory and visual speech information in the domains of speed and accuracy is associated with auditory sensory capabilities and possibly other sensory and cognitive factors.     

The effect of cochlear implants on cognitive function in older adults: A prospective,longitudinal 2-year follow-up study

ObjectivesIt is shown that eliminating hearing loss in mid-life may reduce the risk for deterioration in cognitive function. Cochlear implantation (CI) is the only available therapy that can eliminate hearing loss in patients who suffer from profound sensorineural hearing loss. This suggests there may be positive effects of hearing level on cognition in older adults following CI. Therefore, the purpose of this study is to clarify whether cognitive function can be improved or maintained using cochlear implants in older adult patients with hearing impairments.MethodsData for patients that underwent CI surgery for profound bilateral sensorineural hearing loss were collected prospectively. Patients aged 65 years and older were recruited at our university hospital from 2013 to 2017. Twenty-one patients (age range: 65–80 years) were included in this study. The primary outcome measurement was the change in cognitive function three points assessed by Mini-Mental State Examination (MMSE): preoperatively, and at 1 and 2 years after surgery. The secondary outcome measurements were the followings; the Nijmegen Cochlear Implant Questionnaire (NCIQ), the Self-Rating Depression Scale (SDS), and hearing and speech recognition threshold assessment before CI, and 1 and 2 years after CI. Differences in MMSE scores were compared for statistical significance using the Friedman test. The Wilcoxon signed-rank test was used as a post hoc test. Possible correlations between MMSE scores and NCIQ subdomain scores 2 years after surgery were evaluated with Spearman's tests. Statistical significance was defined as a p-value <0.05.ResultsCI recipients showed significant improvement in MMSE scores. This improvement peaked 1 year after CI surgery. The postoperative MMSE score was correlated with the NCIQ speech production score but not with the other five NCIQ subdomains. There was no correlation between MMSE score and speech recognition.ConclusionSpeech production is important to improve cognitive function after CI, and this improvement peaked 1 year after CI. Although severe or profound hearing loss in older adults worsens the natural course of cognitive function decline, CI has positive impacts on cognitive function even if MMSE scores decrease 1 year after the peak (i.e., 2 years after CI). Talking with others based on hearing is crucial to improve cognitive function. We should encourage older adult patients to take many opportunities to talk with others after CI surgery.