持续进行性口吃患者的言语声诱发听性脑干反应

持续进行性口吃(persistent developmental stuttering,PDS)是一种儿童时期发病至成人仍不恢复的言语流畅障碍性疾病,发病机制至今尚未明确.一些电生理学研究表明口吃患者存在着听觉皮层的功能障碍,其听觉信息处理缺陷被认为是其基础机制.最近神经学研究发现,PDS患者皮层下中枢的听觉和运动区(例如基底神经节)出现异常神经活动.有学者指出,听觉脑干可能是PDS患者听觉中枢功能的缺陷部位.     

The use of cortical auditory evoked potentials to evaluate neural encoding of speech sounds in adults

There has been considerable recent interest in the use of cortical auditory evoked potentials (CAEPs) as an electrophysiological measure of human speech encoding in individuals with normal as well as impaired auditory systems. The development of such electrophysiological measures such as CAEPs is important because they can be used to evaluate the benefits of hearing aids and cochlear implants in infants, young children, and adults that cannot cooperate for behavioral speech discrimination testing. The current study determined whether CAEPs produced by seven different speech sounds, which together cover a broad range of frequencies across the speech spectrum, could be differentiated from each other based on response latency and amplitude measures. CAEPs were recorded from ten adults with normal hearing in response to speech stimuli presented at a conversational level (65 dB SPL) via a loudspeaker. Cortical responses were reliably elicited by each of the speech sounds in all participants. CAEPs produced by speech sounds dominated by high-frequency energy were significantly different in amplitude from CAEPs produced by sounds dominated by lower-frequency energy. Significant effects of stimulus duration were also observed, with shorter duration stimuli producing larger amplitudes and earlier latencies than longer duration stimuli. This research demonstrates that CAEPs can be reliably evoked by sounds that encompass the entire speech frequency range. Further, CAEP latencies and amplitudes may provide an objective indication that spectrally different speech sounds are encoded differently at the cortical level.     

言语诱发听性脑干反应的潜伏期特性分析

目的探讨不同刺激强度下健康成人言语诱发听性脑干反应（speech evoked auditory brainstem response,speech-ABR）的潜伏期特性及其在脑干神经元编码言语信息中的意义。方法记录32例健康成人32耳在4种刺激强度（20、40、60、80dBSPL）、11.1次/s速率下的speech-ABR,分析不同强度条件下speech-ABR的潜伏期和相关性。结果 speech-ABR由一系列主波组成,分为起始部分（包括V和A波）、过渡部分（C波）、频率跟随部分（D-E-F波）和终止部分（O波）。随着强度的降低,各主波潜伏期逐渐延长,差异有统计学意义（P〈0.05）。强度降低20dBSPL级差时,潜伏期的平均延长值表现为V、A、C、O波接近,D、E、F波接近。不同强度下,V-A-C波潜伏期之间、D-E波潜伏期、E-F波潜伏期的相关性均有统计学意义,且相关系数大于0.40,其中V-A波潜伏期的相关系数大于0.80;强度降低时,潜伏期间的相关性有统计学意义的主波逐渐增多。结论健康成人speech-ABR各主波的潜伏期随着刺激强度降低而显著延长;起始反应和频率跟随反应的潜伏期及其显著相关性具有不同的变化特点。言语强度降低时,speech-ABR主波潜伏期的显著延长以及主波潜伏期间相关性的改变可能与言语的不易被识别有关。     

Central processing of speech sounds and non-speech sounds with similar spectral distribution: An auditory evoked potential study

ObjectiveThe purpose of this study was to measure the auditory evoked potentials for speech and non-speech sounds with similar spectral distributions.MethodsWe developed two types of sounds, comprising naturally spoken vowels (natural speech sounds) and complex synthesized sounds (synthesized sounds). Natural speech sounds consisted of 5 Japanese vowels. Synthesized sounds consisted of a fundamental frequency and its second to fifteenth harmonics equivalent to those of natural speech sounds. The synthesized sound was filtered to have a similar spectral distribution to that of each natural speech sound. These sounds were low-pass filtered at 2000 Hz. The auditory evoked potential elicited by the natural speech sound /o/ and synthesized counterpart for /o/ were measured in 10 right-handed healthy adults with normal hearing.ResultsThe natural speech sounds were significantly highly recognized as speech compared to the synthesized sounds (74.4% v.s. 13.8%, p < 0.01). The natural speech and synthesized sounds for the vowel /o/ contrasted strongly for speech perception (96.9% vs. 9.4%, p <0.01). However, the vowel /i/ and its counterpart were barely recognized as speech (4.7 v.s. 3.1%, p = 1.00). The N1 peak amplitudes and latencies evoked by the natural speech sound /o/ were not different from those evoked by the synthesized sound (p = 0.58 and p = 0.28, respectively). The P2 amplitudes evoked by the natural speech sound /o/ were not different from those evoked by the synthesized sound (p = 0.51). The P2 latencies evoked by the natural speech sound /o/ were significantly shorter than those evoked by the synthesized sound (p < 0.01). This modulation was not observed in a control study using the vowel /i/ and its counterpart (p = 0.29).ConclusionThe early P2 observed may reflect central auditory processing of the ‘speechness’ of complex sounds.     

Delayed brainstem auditory evoked responses in diabetic patients

The incidence of subclinical central diabetic neuropathy is unclear due to difficulty in detecting latent alterations of central neural transmission process. The aim of this study was to evaluate a central neuroconductive mechanism in diabetics by brainstem auditory evoked responses (BAER). We found increased latencies of peaks I, III, V in diabetics as compared to control subjects. These BAER abnormalities were demonstrated in 62 per cent of insulin-controlled diabetics and in 33 per cent o patients treated by diet, or peroral drugs. No alterations in brainstem responses were observed in patients with latent diabetes. We did not find any correlation between the BAER abnormalities and the duration of the disease, the blood glucose level or the level of control of the diabetes.     

Speech evoked auditory brainstem response findings in children with epilepsy

Objectives

Children with epilepsy are at a considerable risk of cognitive impairment and school failure. Previous studies have typically documented abnormal responses in children with epilepsy at cortical level using speech stimuli. Recent studies reported that abnormal neural encoding of a speech syllable could be detected at the level of the brainstem using speech-evoked auditory brainstem response (ABR). The aim of this study is to investigate speech-evoked (ABR) results in children with epilepsy.

Methods

The study group consisted of 38 recently diagnosed epileptic children; none of them has received antiepileptic therapy. They were 22 males and 16 females with age 9.1 ± 3.1 years. The control group consisted of 38 healthy normal hearing children with matched age and gender distribution. All subjects underwent full history taking, basic audiologic evaluation including pure-tone, speech audiometry and immittance testing. Click ABR response was recorded monaurally from both ears at 90 dB nHL then speech ABR was recorded monaurally from each ear at 80 dB SPL.

Results

Though the study group disclosed normal click ABR compared to age matched normative values, speech-evoked ABR revealed a delayed waves V and A latencies in both ears. These findings reflect abnormal neural encoding of speech at the level of brainstem. The younger the age of epileptic child the more prolonged wave A latency and increased V/A inter-latency values.

Conclusions

Speech-evoked ABR results denote abnormal timing in the brainstem; such brainstem abnormality could be detected by speech evoked ABR rather than conventional click evoked ABR.     

Development of brainstem auditory evoked responses in the hamster

The hamster is relatively immature at birth compared with other mammalian species. Because of the amount of maturation that occurs postnatally, the development of the peripheral auditory system of the hamster has generated a great deal of interest. However, indices of the developing functional capabilities of the central auditory system of the hamster are lacking. The following study investigated the ontogeny of brainstem auditory evoked responses (BAERs) to clicks in young hamsters. The general maturational trends noted for other species were found for the hamster. The major peaks of the BAER decrease in latency at the same time relative to birth and at the same rate in the hamster as in the cat and rat. Some maturational events such as the onset of a recordable BAER, appearance of the late peaks and increase in amplitude of the late peaks occur later, relative to birth, in the hamster than in the other species. Development delays in the hamster make it an attractive model for studying postnatal development of the central auditory system.     

电诱发听性脑干反应（EABR）的临床应用

电诱发听性脑干反应（electrically evoked auditory brainstem responses，EABR）是一种客观的神经电生理检测方法．在耳科学、听力学和神经科学中占有重要的地位。EABR可以估测耳聋患者残存的听神经末梢螺旋神经节数量．客观评价听觉传导通路的功能状态．指导人工耳蜗植入手术及听性脑干植入手术．并在术后设备调试中起重要作用。本文对EABR的临床应用现状及前景做一综述。     

Delayed brainstem auditory evoked responses in experimental diabetes mellitus

The brainstem auditory evoked responses (BAER) were utilized for the evaluation of central neural transmission in alloxan-induced diabetes in rats. The mean latencies of waves I, III, V and the interpeak latencies III-V and I-V were prolonged in diabetic rats as compared to the same rats before alloxan administration. The incidence of abnormal BAER was more frequent in the group of rats with severe diabetes (82 per cent) than in mildly diabetic animals (42 per cent). Our results may suggest the presence of a central neuropathy in experimental diabetes, which can be detected by the method of BAER.     

Effect of stimulation parameters on electrically evoked auditory brainstem responses

It is evident that the conventional technique for cochlear implant adjustment is not suitable for children in their first years of life. In order to find a solution to this problem, the possibility of electrically evoked auditory brainstem response (EABR) recording was investigated. EABRs were recorded in 9 patients with the Nucleus multichannel cochlear implant. The main problems that have to be solved during EABR recording in cochlear implantees are: i) EABR distortion due to the stimulus artefact: and ii) difference in the stimulus presentation rate during EABR registration (low pulse rate) and conventional psychophysical threshold estimation (high pulse rate) in cochlear implant patients. The influence of stimulus artefact on the recording results was minimized by setting the implant to the widest amplifier frequency band and by zeroing the initial segment containing the stimulus artefact with subsequent zero-phase digital filtering. The dependence of the EABR amplitude and latency on the stimulus intensity, width, electrode location and interstimulus interval was investigated. It was concluded that despite the difference revealed between absolute values of EABR thresholds and psychophysical threshold levels, it is possible to calculate implant adjustment parameters based on the EABR data with the proper correction applied.     

Gender disparity in subcortical encoding of binaurally presented speech stimuli: An auditory evoked potentials study

Objectives

To investigate the influence of gender on subcortical representation of speech acoustic parameters where simultaneously presented to both ears.

Methods

Two-channel speech-evoked auditory brainstem responses were obtained in 25 female and 23 male normal hearing young adults by using binaural presentation of the 40 ms synthetic consonant-vowel /da/, and the encoding of the fast and slow elements of speech stimuli at subcortical level were compared in the temporal and spectral domains between the sexes using independent sample, two tailed t-test.

Results

Highly detectable responses were established in both groups. Analysis in the time domain revealed earlier and larger Fast-onset-responses in females but there was no gender related difference in sustained segment and offset of the response. Interpeak intervals between Frequency Following Response peaks were also invariant to sex. Based on shorter onset responses in females, composite onset measures were also sex dependent. Analysis in the spectral domain showed more robust and better representation of fundamental frequency as well as the first formant and high frequency components of first formant in females than in males.

Conclusions

Anatomical, biological and biochemical distinctions between females and males could alter the neural encoding of the acoustic cues of speech stimuli at subcortical level. Females have an advantage in binaural processing of the slow and fast elements of speech. This could be a physiological evidence for better identification of speaker and emotional tone of voice, as well as better perceiving the phonetic information of speech in women.     

Electrically evoked auditory brainstem responses in cochlear implant patients.

Electrically evoked auditory brainstem responses (EABR) were recorded in completely deaf patients implanted with Ineraid multichannel cochlear implants. Clear and reproducible EABR were obtained from all patients. Parametric differences with auditory brainstem responses (ABR) were demonstrated and can be explained by the different natures of both types of stimulations (electric versus acoustic). Evidence is given that other well-known properties of auditory evoked responses, like 'binaural interaction' or suppression of responses in a forward masking paradigm, can be observed in EABR of implanted patients.     

双耳同侧记录的言语诱发听性脑干反应的对比研究

目的:比较左、右耳记录的言语诱发听性脑干反应(speech-ABR)在时域及频域上的差异,探讨脑干编码不同耳别来源的言语信息的差异及其可能原因。方法:以合成言语/da/为刺激声对健康成人进行双耳同侧记录的speech-ABR测试,分析反应的潜伏期、幅值及波形评分。对反应20～50ms部分进行快速傅立叶变换,计算基频及第一共振峰的幅值。结果:不同耳别记录的speech-ABR主波的潜伏期差异无统计学意义;右耳记录的A波幅值显著大于左耳记录,O波幅值则显著小于左耳记录,其他主波幅值的耳别差异均无统计学意义。右耳记录的波形评分大于左耳记录,两者差异有统计学意义。无论记录耳别,基频的幅值均大于第一共振峰的幅值,差异有统计学意义;无论是基频的幅值还是第一共振峰的幅值,耳别差异均无统计学意义。结论:speech-ABR在脑干的来源和分布无明显偏向性,与大脑半球言语功能的不对称性无明显对应性。听觉传导通路、功能性what-where通路以及大脑两侧半球不是简单的对应关系。     

The latency of auditory nerve brainstem evoked responses to air- and bone-conducted stimuli

The auditory nerve brainstem evoked responses (ABRs) to bone conduction (BC) stimuli are longer in latency than those to air conduction (AC). In order to study the mechanism of this difference, ABR wave I was recorded in experimental animals in response to low intensity (0–20 dB above their threshold) logon stimuli delivered by BC and by using the same bone vibrator to generate the air-conducted stimulus. The BC stimuli were delivered to skull bone, and directly to the contents of the cranial cavity (brain and cerebrospinal fluid) through a craniotomy. ABR wave I in response to BC stimuli delivered to skull bone was significantly longer in latency than that to BC delivered on the brain, while there was no latency difference between AC stimuli and BC to the brain. Furthermore, the vibration (measured with an accelerometer) recorded on the brain during BC stimulation of skull bone was always delayed compared to that measured on the skull. Thus there is a delay in the transfer of vibratory energy from the skull bone to the underlying contents of the cranial cavity. From there, the delayed vibrations of the contents of the cranial cavity are transmitted to the inner ear. This is probably the mechanism of the longer latency BC response compared to the AC response.     

The progress of adrenoleukodystrophy as revealed by auditory brainstem evoked responses and brainstem histology

Summary Serial studies of auditory brainstem evoked responses (ABR) and slow vertex responses (SVR) were obtained during the progress of adrenoleukodystrophy in a 6-year-old boy. This child was normal until 5 years of age. His illness began with a gait disturbance, dysarthria, and hearing difficulty. Later, spastic paralysis, serious deafness, and blindness appeared. He died of respiratory failure 2 years after the onset.The ABR was normal at onset but changed to an abnormal pattern. Initially, there was lengthening of the wave V-I interpeak interval. This was followed by the disappearance of the later components as his general condition deteriorated. At the terminal stage, only a prolonged wave I was recordable. The postmortem pathology revealed demyelination of auditory nerves and remarkable neuronal loss in the auditory pathways of the brainstem; in addition, there was a variety of extensive degeneration throughout the cerebrum, in particular the complete degeneration of the white matter with secondarily occurring ganglionic cell changes. These data suggest that degeneration of the brainstem from rostral to caudal levels occurred.     

Measurement of auditory brainstem responses evoked by electrical stimulation with a cochlear implant

Auditory brainstem responses evoked by electrical stimulation with a Nucleus/Cochlear implant can be measured if care is taken to prevent stimulus artefacts. A simple procedure is described which relies upon a passive LCR filter to prevent the radiofrequency carrier from entering the input of the recording amplifier. The filter simply prevents saturation of the amplifier by the carrier.