Cortical auditory evoked responses from an implanted ear after 50 years of profound unilateral deafness

A male with unilateral deafness in the right ear since 8 years of age developed a sudden hearing loss in the left ear at age 63. A hearing aid was fitted in the left ear with limited benefit. The right ear received a cochlear implant (CI) 20 months later. Cortical auditory evoked potentials (CAEPs) and speech recognition scores (SRS) were measured in free-field three, six and nine months after implantation with the hearing aid alone, CI alone and bimodal condition (hearing aid and CI together). Three months after implantation the cortical responses for the two ears were similar, despite more than 50 years of unilateral auditory deprivation. CAEPs measured over time show evidence of binaural interaction and improvements in SRS.     

Cortical auditory evoked potential (CAEP) and behavioural measures of auditory function in a child with a single-sided deafness

Objectives: To study the changes in behavioural and cortical responses over time in a child with single-sided deafness fitted with a cochlear implant (CI).

Methods: Cortical auditory evoked potentials (CAEPs) in noise (+5?dB signal-to-noise ratio) were recorded and auditory skills were assessed using tests of sound localization, spatial speech perception in noise, and self-ratings of auditory abilities (Listening inventory for education, LIFE and Speech, spatial and qualities of hearing questionnaire, SSQ parental version). Measures were obtained prior to and after a CI fitting, including one, six, and 12 months after the CI switch on.

Results: Spatial speech recognition improved over time. At 12 months post-CI, word recognition scores were similar to those of normal hearing children. Signal-to-noise ratios for sentences decreased (i.e. improved) over time post-CI. Sound localization markedly improved at 12 months post-CI compared to baseline. Self-perception of difficulty scores decreased over time. Parental ratings of hearing abilities improved compared to baseline for all subscales. There were changes in the P1–N1–P2 complex at 12 months post-CI, which were clearer frontally across stimuli. Further research is needed to understand the significance of such changes after CI fitting for single-sided deafness.

Conclusion: Although the changes observed could reflect maturational changes, the clinically significant improvement in recognition of speech in noise and improved questionnaire results suggest that the CI was beneficial, consistent with the feedback from the participant.     

Plasma antidiuretic hormone in cases with the early onset of profound unilateral deafness

Objective

The p-ADH level in cases of juvenile unilateral profound deafness (JUPD) and the timecourse of the level were examined to investigate whether or not an increase of p-ADH is involved in the development of delayed endolymphatic hydrops (DEH) in JUPD.

Materials and methods

In 90 consecutive patients with unilateral profound or total sensorineural deafness with the onset in early childhood, pure-tone audiometric examination and the measurement of p-ADH and plasma osmolality (p-OSM) were followed up once or twice a year as far as possible. At every testing, we performed careful history-taking about episodic vertigo/dizziness, fluctuant hearing loss, and tinnitus in order to find out whether patients had experienced these clinical signs of the development of DEH.

Results

Means and standard deviation (S.D.) of p-ADH level and osmolality in all samples tested (n = 368) were 7.3 ± 7.0 pg/mL (0.7–52.0 pg/mL), and 288.6 ± 4.4 mOsm/L (273–306 mOsm/L), respectively. The mean of p-ADH level was much higher than those previously reported in children and adolescents. High levels of p-ADH (over 5.0 pg/mL) were often observed in subjects between 6 and 19 years of age, but not so frequently in subjects of 20 years of age or older. Long-term follow-up of p-ADH levels revealed that DEH frequently developed in cases with persistent elevation of p-ADH.

Conclusions

The elevation of p-ADH is likely to promote the development of DEH in cases of JUPD, although the underlying mechanism remains to be elucidated.     

Altered Cortical Activity in Prelingually Deafened Cochlear Implant Users Following Long Periods of Auditory Deprivation

Auditory stimulation during childhood is critical for the development of the auditory cortex in humans and with that for hearing in adulthood. Age-related changes in morphology and peak latencies of the cortical auditory evoked potential (CAEP) have led to the use of this cortical response as a biomarker of auditory cortical maturation including studies of cortical development after deafness and subsequent cochlear implantation. To date, it is unknown whether prelingually deaf adults, with early onset deafness (before the age of 2 years) and who received a cochlear implant (CI) only during adulthood, would display absent or aberrant CAEP waveforms as predicted from CAEP studies in late implanted prelingually deaf children. In the current study, CAEP waveforms were recorded in response to electric stimuli in prelingually deaf adults, who received their CI after the age of 21 years. Waveform morphology and peak latencies were compared to the CAEP responses obtained in postlingually deaf adults, who became deaf after the age of 16. Unexpectedly, typical CAEP waveforms with adult-like P1-N1-P2 morphology could be recorded in the prelingually deaf adult CI users. On visual inspection, waveform morphology was comparable to the CAEP waveforms recorded in the postlingually deaf CI users. Interestingly, however, latencies of the N1 peak were significantly shorter and amplitudes were significantly larger in the prelingual group than in the postlingual group. The presence of the CAEP together with an early and large N1 peak might represent activation of the more innate and less complex components of the auditory cortex of the prelingually deaf CI user, whereas the CAEP in postlingually deaf CI users might reflect activation of the mature neural network still present in these patients. The CAEPs may therefore be helpful in the assessment of developmental state of the auditory cortex.     

Desynchronisation of auditory steady-state responses related to changes in interaural phase differences: an objective measure of binaural hearing

Objective: Binaural processing can be measured objectively as a desynchronisation of phase-locked neural activity to changes in interaural phase differences (IPDs). This was reported in a magnetoencephalography study for 40?Hz amplitude modulated tones. The goal of this study was to measure this desynchronisation using electroencephalography and explore the outcomes for different modulation frequencies. Design: Auditory steady-state responses (ASSRs) were recorded to pure tones, amplitude modulated at 20, 40 or 80?Hz. IPDs switched between 0 and 180° at fixed time intervals. Study sample: Sixteen young listeners with bilateral normal hearing thresholds (≤25?dB HL at 125–8000?Hz) participated in this study. Results: Significant ASSR phase desynchronisations to IPD changes were detected in 14 out of 16 participants for 40?Hz and in 8, respectively 9, out of 13 participants for 20 and 80?Hz modulators. Desynchronisation and restoration of ASSR phase took place significantly faster for 80?Hz than for 40 and 20?Hz. Conclusions: ASSR desynchronisation to IPD changes was successfully recorded using electroencephalography. It was feasible for 20, 40 and 80?Hz modulators and could be an objective tool to assess processing of changes in binaural information.     

听力筛查转诊婴幼儿不同滤波条件短纯音诱发听性脑干反应的比较

目的 短纯音诱发听性脑干反应(ABR)是听力筛查转诊婴幼儿听力评估的重要方法,本研究比较滤波分别为30～1500 Hz与30～3000 Hz时不同频率短纯音ABR阈值之间的差异,总结两种滤波条件下ABR波形特点及对阈值判断的影响,以选择更优化的频率特异性ABR测试参数.方法 应用美国IHS公司SmartEP听觉诱发电位仪记录18例(22耳)2～33月龄婴幼儿短声、滤波为30～1500 Hz与30～3000 Hz短纯音ABR各频率反应阈.结果 0.5 kHz、1 kHz、2 kHz、4 kHz滤波为30～3000 Hz短纯音ABR反应阈比滤波为30～1500 Hz短纯音ABR反应阈高.0.5 kHz及2.0 kHz两种滤波条件下短纯音ABR反应阈之间差异具有统计学意义(t值分别为2.238及2.217,P值均＜0.05),其他频率两种滤波条件下反应阈之间差异无统计学意义(P值均＞0.05).同等刺激强度下,滤波为30～3000 Hz的ABR波形与30～1500 Hz相比不平滑,反应波曲线上会出现锯齿状细小的干扰波.结论 在用短纯音ABR反应阈评估婴幼儿听力时,30～1500 Hz可以作为更优化的滤波设置参数.

Abstract：

Objective Auditory brainstem responses (ABR) evoked by tone burst is an important method of hearing assessment in referral infants after hearing screening. The present study was to compare the thresholds of tone burst ABR with filter settings of 30 - 1500 Hz and 30 - 3000 Hz at each frequency,figure out the characteristics of ABR thresholds with the two filter settings and the effect of the waveform judgement, so as to select a more optimal frequency specific ABR test parameter. Methods Thresholds with filter settings of 30 - 1500 Hz and 30 -3000 Hz in children aged 2 -33 months were recorded by click,tone burst ABR. A total of 18 patients ( 8 male / 10 female), 22 ears were included. Results The thresholds of tone burst ABR with filter settings of 30 - 3000 Hz were higher than that with filter settings of 30 - 1500 Hz. Significant difference was detected for that at 0. 5 kHz and 2.0 kHz ( t values were 2.238 and 2. 217, P ＜ 0. 05 ), no significant difference between the two filter settings was detected at the rest frequencies tone evoked ABR thresholds. The waveform of ABR with filter settings of 30 - 1500 Hz was smoother than that with filter settings of 30 - 3000 Hz at the same stimulus intensity. Response curve of the latter appeared jagged small interfering wave. Conclusions The filter setting of 30 - 1500 Hz may be a more optimal parameter of frequency specific ABR to improve the accuracy of frequency specificity ABR for infants' hearing assessment.     

Cortical auditory evoked potential in assessment of neonates: a study about minimum level of responses in term and preterm newborns

IntroductionThe study of the threshold level of cortical auditory response in adults has been investigated in previous studies. Due to maturational issues, little is known about these responses in neonates. Technological advances with automatic analysis devices now allow investigation in specific populations. Thus, new studies are needed to establish the feasibility of using this auditory potential to identify the lowest levels of responses in children.ObjectiveVerify and compare latency and amplitude in 80 dBnNA and the minimum level of cortical auditory response in term and preterm neonates.MethodsA cross-sectional, comparative study involving 59 neonates, 35 full-term births and 24 preterm births, with positive results in the Neonatal Hearing Screening. The Hearlab system was used to investigate the P1i auditory potential with tone burst stimulus at frequencies of 500, 1000, 2000 and 4000 Hz. The minimum response level search ranged from 80 to 0 dBNA and was detected automatically. The results were compared between groups, evaluating the latency and amplitude in 80 dBNA and the minimum level of cortical auditory response.ResultsThe mean values obtained for the minimum level of cortical auditory response in term group were 26 ± 8.81; 26.14 ± 6.97; 29 ± 7.65 and 29.43 ± 7.04 dBNA and for preterm neonates of 31.96 ± 10.41; 34.13 ± 11.34; 33.64 ± 11.03 and 37.73 ± 11.92 dBNA, for the frequencies of 500, 1000, 2000 and 4000 Hz, respectively. There was a difference between groups for the latency of P1i at 4000 Hz and the minimum response levels at 500, 1000 and 4000 Hz, with higher values for preterm infants.ConclusionIt was possible to obtain latency and amplitude values at 80 dBnNA and the minimum level of cortical response in term and preterm newborns, with different results between groups, with higher values in those born preterm.     

Binaural interactions of electrically and acoustically evoked responses recorded from the inferior colliculus of guinea pigs

Binaural interactions within the inferior colliculus (IC) elicited by electric and acoustic stimuli were investigated in this study. Using a guinea pig model, binaural acoustic stimuli were presented with different time delays, as were combinations of binaural electric and acoustic stimuli. Averaged evoked potentials were measured using electrodes inserted into the central nucleus of the IC to obtain the binaural interaction component (BIC), computed by subtracting the sum of the two monaural responses from the binaural response. The BICs to acoustic-acoustic stimulation and electric-acoustic stimulation were found to be similar. The BIC amplitude increased with stimulus intensity, but the shapes of the delay functions were similar across the levels tested. The gross-potential data are thus consistent with the thesis that the central auditory system processes binaural electric and acoustic stimuli in a similar manner. These results suggest that the binaural auditory system can process combinations of electric and acoustic stimulation presented across ears and that evoked gross potentials may be used to measure such interaction.