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

Abstract

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. Copyright © 2007 John Wiley & Sons, Ltd.     

Averaged evoked auditory responses in the chronically implanted cat

Averaged evoked auditory responses from chronically implanted dural electrodes over the midectosylvian gyrus were evaluated in eight cats. The effects of the distribution of electrodes and levels of alertness were observed for each animal and the entire group. Changes in duration, rise and decay times, and repetition rates were also analyzed. Data from these experiments suggested a large variability in the amplitude and latency of the response. On the other hand, they also suggested a stable reproducible threshold of detectability — a point where the response disappeared upon further reduction in sound pressure levels. This characteristic of the evoked system served as a reliable measurement of an evoked auditory threshold and appeared as a potential means for evaluating relative changes of auditory function within the same animal.     

Plasticity in the adult human central auditory system: evidence from late-onset profound unilateral deafness.

Experience-related changes in central nervous system (CNS) activity have been observed in the adult brain of many mammalian species, including humans. In humans, late-onset profound unilateral deafness creates an opportunity to study plasticity in the adult CNS consequent to monaural auditory deprivation. CNS activity was assessed by measuring long-latency auditory evoked potentials (AEPs) recorded from teens and adults with late-onset (post-childhood) profound unilateral deafness. Compared to monaurally stimulated normal-hearing subjects, the AEPs recorded from central electrode sites located over auditory cortical areas showed significant increases in inter-hemispheric waveform cross-correlation coefficients, and in inter-hemispheric AEP peak amplitude correlations. These increases provide evidence of substantial changes from the normal pattern of asymmetrical (contralateral > ipsilateral amplitude) and asynchronous (contralateral earlier than ipsilateral) central auditory system activation in the normal-hearing population to a much more symmetrical and synchronous activation in the unilaterally deaf. These cross-sectional analyses of AEP data recorded from the unilaterally deaf also suggest that the changes in cortical activity occur gradually and continue for at least 2 years after the onset of hearing loss. Analyses of peak amplitude correlations suggest that the increased inter-hemispheric symmetry may be a consequence of changes in the generators producing the N (approximately 100 ms peak latency) potential. These experience-related changes in central auditory system activity following late-onset profound unilateral deafness thus provide evidence of the presence and the time course of auditory system plasticity in the adult brain.     

正常耳与聋耳电诱发听性脑干反应实验动物的研究

目的 通过耳蜗外电刺激探讨正常听力与致聋家猫耳蜗EABR检测效果的差异性.方法 选取听力正常家猫,行蜗外EABR检测,刺激电极置于圆窗龛6点和12点方向,分别记录EABR;联合应用卡那霉素和利尿酸钠制备重度耳聋实验动物模型,行蜗外圆窗龛6点方向的EABR检测,比较不同耳蜗外位点及致聋前后EABR的差异.结果 圆窗龛6点方向时EABR阈值为529+27μA,Ⅲ波及Ⅳ波潜伏期为2.16+0.12ms,2.91+0.14ms,12点方向时阈值为545+44μA,Ⅲ波及Ⅳ波潜伏期为2.18±0.13ms,2.93±0.10ms,两者无统计学差异(P＞0.05);致聋前EABR阈值为525+23μA,Ⅲ波及Ⅳ波潜伏期为2.16±0.11ms,2.89±0.14ms,致聋后EABR阈值为558+37μA,Ⅲ波及Ⅳ波潜伏期为2.17±0.09ms,2.91±0.12ms,致聋前后阈值及波潜伏期相比均无统计学差异.结论 刺激电极位点位于圆窗龛6点和12点方向时,EABR阈值及Ⅲ、Ⅳ波潜伏期无统计学差异,但6点方向时波形更容易引出;聋耳EABR波形形态与正常耳EABR形态相似,致聋前与致聋后EABR阈值、Ⅲ波及Ⅳ波潜伏期相比均无统计学差异.     

Cortical auditory responses according to hearing rehabilitation in unilateral hearing loss

ObjectiveTo assess the impact of rehabilitation systems (CROS: Contralateral Routing of Signal; BAHA: Bone-Anchored Hearing Aid; CI: cochlear implant) on cortical auditory evoked potentials (CAEP) and auditory performance in unilateral hearing loss.Subjects and methodTwenty-one adults with unilateral hearing loss, using CROS (n = 6), BAHA (n = 6) or CI (n = 9), were included. Seven normal-hearing subjects served as controls. CAEPs were recorded for a (/ba/) speech stimulus; for patients, tests were conducted with and without their auditory rehabilitation. Amplitude and latency of the various CAEP components of the global field power (GFP) were measured, and scalp potential fields were mapped. Behavioral assessment used sentence recognition in noise, with and without spatial cues.ResultsOnly CI induced N1 peak amplitude change (P < 0.05). CI and CROS increased polarity inversion amplitude in the contralateral ear, and frontocentral negativity on the scalp potential map. CI improved understanding when speech was presented to the implanted ear and noise to the healthy ear, and vice-versa.ConclusionCochlear implantation had the greatest impact on CAEP morphology and auditory performance. A longitudinal study could analyze progression of cortical reorganization.     

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.     

Imaging assessment of profound sensorineural deafness with inner ear anatomical abnormalities

Objective: : To explore the value of a combined computed tomography(CT) and magnetic resonance imaging(MRI) in evaluating profound sensorineural deafness patients before cochlear implant(CI) surgery.Methods: A retrospective analysis of 1012 cases of profound sensorineural deafness that received CI was performed.Results: A total of 96 cases were diagnosed with inner ear abnormalities including large vestibular aqueduct syndrome(LVAS, n ? 61), Michel deformity(n ? 3), cochlear incomplete partition I(n ? 2), cochlear incomplete partition II(n ? 6), cochlear hypoplasia with vestibular malformation(n ? 3), cochlear ossification(n ? 3), bilateral internal auditory canal obstruction(n ? 5) and internal auditory canal stenosis(n ? 2).Conclusion: High resolution CT(HRCT) can display bony structures while MRI can image the membranous labyrinth in preoperative evaluation for cochlear implantation. The combination of these two modalities provides reliable anatomical information regarding the bony and membranous labyrinths, as well as the auditory nerve.     

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.     

Bilateral acute profound deafness after MMR vaccination--report of a case

In April 1989 the MMR vaccination program had started, and until October, 1989, 630,000 children received vaccination. In is, however, well known that many children developed various complication including aseptic meningitis after vaccination, and the MMR vaccination program has discontinued. This report described a case of bilateral acute profound deafness most likely due to MMR vaccination. The cause of this deafness was presumed to be mumps vaccination. The bases of the presumption are as follows: the meningitis after MMR vaccination was elicited by PCR method to be caused by mumps vaccine, and the complication of CNS after measles vaccination occurs within 14 days after injection, while the onset of vomiting and gait disturbance of the case was 24 days after vaccination.     

Usefulness of measuring electrically evoked auditory brainstem responses in children with inner ear malformations during cochlear implantation

Conclusions: EABR is a reliable and effective way of objectively confirming device function and implant-responsiveness of the peripheral auditory neurons up to the level of the brainstem in cases of inner ear malformation. Objective: To investigate the usefulness of measuring the intra-operative electrically evoked compound action potential (ECAP) and electrically evoked auditory brainstem response (EABR) in patients with and without congenital inner ear anomalies during cochlear implantation. Method: Thirty-eight consecutive children (40 ears) aged 5 or younger with congenital profound hearing loss. Twenty-four (25 ears) lacked congenital inner ear anomalies. The 14 patients (15 ears) with a malformation had common cavities (four ears), incomplete partition type I (three ears), cochlea hypoplasia type III (three ears), enlarged vestibular aqueduct (four ears), and cochlear nerve canal stenosis (one ear). Main outcome measures are ECAP and EABR responses. Results: Of the 25 ears lacking any malformation, 21, three, and one showed ‘Good’, ‘Variable’, and ‘No’ ECAP responses, respectively, and 24 and one showed ‘Good’ and ‘Variable’ intra-cochlear responses, respectively. Of the 15 ears with a malformation, two showed ‘Good’ ECAP responses, nine had ‘Variable’ ECAP responses, and four showed ‘No’ ECAP responses. Moreover, five showed ‘Good’ EABR responses and 10 showed ‘Variable’ EABR responses.     

Clinical application of auditory nerve responses recorded from the ear canal.

The practicality of recording auditory nerve responses in the routine practice of an otologist is demonstrated. Such recordings are particularly useful when the course of treatment requires a distinction between central or peripheral disorders. They are also helpful when it is difficult to obtain a valid audiogram. The electrical recordings from the auditory nerve can, in combination with standard audiological, otological and neurological examinations, present a more accurate picture of the patient's condition.     

Bone-anchored hearing aids in unilateral inner ear deafness: an evaluation of audiometric and patient outcome measurements.

OBJECTIVE: To evaluate the benefit of a bone-anchored hearing aid contralateral routing of sound hearing aid (BAHA CROS hearing aid) in 29 patients with unilateral inner ear deafness. STUDY DESIGN: Prospective clinical follow-up study. SETTING: Tertiary referral center. PATIENTS: Thirty patients were recruited. There were 19 patients with a history of acoustic neuroma surgery and 11 patients with unilateral inner ear deafness due to other causes; 1 patient was excluded. The first 21 patients had also participated in a previous evaluation. INTERVENTION: Audiometric measurements were taken before intervention, when fitted with a conventional CROS, and after BAHA implementation. Patients' subjective benefit was quantified with four different hearing aid-specific instruments: the Abbreviated Profile of Hearing Aid Benefit, the Glasgow Hearing Aid Benefit Profile, the International Outcome Inventory for Hearing Aids, and the Single-Sided Deafness questionnaire. MAIN OUTCOME MEASURES: The same instruments were used at a mean long-term follow-up of 1 year after BAHA implantation. RESULTS: Sound localization in an audiologic test setting was no different from chance level. The main effect of the BAHA CROS that was found was the "lift the head shadow" effect in the speech-in-noise measurements. All instruments also showed positive results in favor of the BAHA CROS at long-term follow-up. CONCLUSIONS: The poor sound-localization results in an audiologic test setting illustrated the inability of patients with unilateral inner ear deafness to localize sounds. The speech-in-noise measurements demonstrated the efficacy of the BAHA CROS to lift the head shadow. Patients were still satisfied at 1-year follow-up, according to the four instruments.