[Measurement of electrical evoked middle latency response in cochlear implantation operation].

OBJECTIVE: To establish the method of conducting electrical evoked middle latency response (EMLR) monitoring in cochlear implantation operation and further to assess the neural response of auditory pathway under electrical stimulation. METHODS: Twenty cases of cochlear implantation subjects were investigated in this study. Fourteen cases were pre-lingual deaf and 6 were post-lingual deaf. The surface recording electrodes were placed on the patients under general anesthesia, with language processor connected to the triggering port of the auditory evoked potential device. After the electrode was implanted, the electrode No.3 was selected to conduct. The electrically evoked auditory nerve compound active potentials (ECAP) were firstly tested in all patients, thereafter the EABR mode was selected, and the stimulation parameters were changed to EMLR mode with monopole biphasic, alternation stimulation, pulse width from 50 to 100 µs, the stimulation intensity decreased or increased from 20 CL above the strength of the ECAP threshold to the reaction threshold with a step of 5CL. To evaluate the correlation between the ECAP thresholds and EMLR, another 6 cases of normal hearing healthy subjects were recruited to record their short-sound evoked auditory middle-latency response (AMLR), as the control of morphology and latency of MLR by electrical stimulation. RESULTS: The typical AMLR waveforms could be recorded by the composition of five waves in the 6 cases of normal hearing healthy subjects, with an average response threshold of (12.5±8.6) dBnHL, close to the behavioral audiometric threshold (10.8±7.3) dBHL. The EMLR waveforms could be recorded in 20 patients, which was similar to the AMLR waveforms. However, the wave latency and wave interval shortened. There were lower volatility and longer latency in pre-lingual deaf than post-lingual deaf. The EMLR threshold (140.55±9.92) CL was significantly lower than the ECAP threshold (160.75±13.34) CL (t=10.467, P<0.01), a positive correlation between the thresholds was detected (r=0.763, P<0.01). CONCLUSIONS: We successfully established the method of EMLR monitoring in cochlear implantation surgery. The EMLR threshold is lower than the ECAP threshold but it is close to the behavioral audiometric threshold; EMLR can provide neural response information closer to the auditory center, and can serve as an effective objective method to evaluate the effect of hearing rehabilitation.

[Efficacy in patients with outer and middle ear deformities of using bone-anchored hearing aids].

OBJECTIVE: To evaluate the efficacy and satisfaction of bone-anchored hearing aids (BAHA) in patients with outer and middle ear deformities. METHODS: Seven patients with bilateral microtia and aural atresia, and three patients with unilateral microtia and bilateral middle ear malformation were fitted with soft-band BAHA for a few months, followed by receiving unilateral BAHA implantation. Mean pure-tone thresholds and speech audiometry tests results were compared among patients without hearing aid, with soft-band BAHA, and with implanted BAHA. Scores from the BAHA users' questionnaires and Glasgow children's benefit inventory (GCBI) were used to measure patient satisfaction and subjective health benefit. RESULTS: The mean pure-tone thresholds of the patients were (64.8 ± 5.9) dBHL for those without hearing aid, (30.2 ± 3.7) dBHL for those with soft-band BAHA, and (20.3 ± 3.9) dBHL for those with implanted BAHA. The average decline in pure-tone threshold was (36.2 ± 8.0) dBHL for those with soft-band BAHA, and an additional decline of (12.2 ± 3.4) dBHL was achieved with implanted BAHA. The average gains in speech discrimination scores (SDS) were (3.00 ± 1.07)% for those without hearing aids and (89.39 ± 5.83)% for those with implanted BAHA in sound field of 45dBHL. SDS were (57.55 ± 10.30)% for those without hearing aids and (91.19 ± 4.16)% for those with implanted BAHA in sound field of 65dBHL. The average gains in SDS were (88.21 ± 6.86)% and (38.04 ± 7.56)% tested with 45dBHL and 65dBHL respectively. Sound reception thresholds (SRT) without hearing aids were (63.1 ± 5.9) dBHL and (24.7 ± 3.5) dBHL for those with implanted BAHA. The average gains in SRT was (39.6 ± 6.2) dBHL. The BAHA application questionnaire demonstrated excellent patient satisfaction. The general benefit score was 35.59 ± 14.35. CONCLUSION: BAHA remains one of the most reliable methods of auditory rehabilitation and improves quality of life for patients with ear deformities.

Application of intraoperative round window electrocochleography for screening the patients with auditory neuropathy.

BACKGROUND: Most patients with auditory neuropathy (AN) could receive good even the best effects after cochlear implantation. How to diagnose AN objectively and accurately is very important. In this study, we screened the patients with AN according to the presence or absence of compound action potential (CAP) of intraoperative round window electrocochleography (RW ECochG). METHODS: Intraoperative RW ECochG was performed on 32 patients with profound sensorineural deafness, who had normal cochlea during cochlear implantation surgery under general anesthesia in the standard operating room. The cochlear microphonic (CM) and CAP of RW ECochG was observed and recorded. RESULTS: The presence of CM but the absence of CAP of RW ECochG occurred in 12 among the 32 patients. They were suspected to suffer from AN. The rest patients who had CM and CAP of RW ECochG were thought not to suffer from AN. CONCLUSION: Application of intraoperative RW ECochG during the cochlear implantation surgery may objectively and accurately screen the patients with AN, and can give a meaningful clue for implanted device working.

Development of the computerized Mandarin pediatric lexical tone and disyllabic-word picture identification test in noise (MAPPID-N).

MAPPID-N was developed to assess the speech-recognition abilities in noise of Mandarin-speaking children on disyllabic words, and lexical tones in monosyllabic words, in a picture-identification test format. Twenty-six normal-hearing children aged four to nine years listened repeatedly to the test materials where noise was spatially mixed with or separated from speech, in different signal-to-noise (SNR) ratios, to obtain performance-SNR functions and SNR for 50% correct scores (SNR-50%). SNR-50% improved with age only when noise was spatially separated from speech but not when noise was mixed with speech, suggesting the improvement with age in the use of intensity and timing cues differences between the two ears. The homogeneity of the test items was improved by adjusting the intensity levels of individual test items to align their SNR-50% to the mean SNR-50% level.

Lexical tone and word recognition in noise of Mandarin-speaking children who use cochlear implants and hearing aids in opposite ears.

The benefits of bimodal hearing (cochlear implant and hearing aid in opposite ears) in children are well documented in English-speaking populations (Ching et al., 2000; Holt et al., 2005) but not much evidence has been reported from populations using tonal languages. The lexical tones in tonal languages are heavily loaded with semantic and grammatical information, which are essentially represented by the fundamental frequency (F0) and low-order harmonics of the speech signal. This unique linguistic feature means that tonal language-speaking CI recipients may achieve more bimodal benefits than their non-tonal language peers may. Twenty Mandarin-speaking children using the Nucleus 24 cochlear implant system and a hearing aid on the non-implant ear were assigned to either one of the two groups to investigate the head-shadow and binaural redundancy effects. A computerized speech test - MAPPID-N (Yuen et al., 2007) was used to present Mandarin lexical tones in monosyllabic words, and disyllabic words with a four- and eight-alternative forced choice picture-identification task, respectively. Individualized signal-to-noise ratio was used to capture the speech scores in the 30%-70% range and was fixed throughout the CI alone and bimodal experimental conditions. Hearing aid fitting was optimized before the first test phase, which was followed by the second test phase after three months. Significant head shadow but not binaural redundancy benefits were observed, suggesting that subjects have not yet developed central binaural processing abilities to improve speech recognition when speech and noise are mixed, in the bimodal condition, in this group of Mandarin-speaking paediatric CI recipients. No subject experienced any degradation of performance in the bimodal versus the CI-only test condition. This may be the first study that demonstrated the bimodal benefits in CI paediatric recipients speaking tonal language, particularly in lexical tone perception. Hearing aid amplification for the non-implant ear should be a standard for the paediatric tonal-language CI population.

Auditory pre-attentive processing of Chinese tones.

BACKGROUND: Chinese tones are considered important in Chinese discrimination. However, the relevant reports on auditory central mechanisms concerning Chinese tones are limited. In this study, mismatch negativity (MMN), one of the event related potentials (ERP), was used to investigate pre-attentive processing of Chinese tones, and the differences between the function of oddball MMN and that of control MMN are discussed. METHODS: Ten subjects (six men and four women) with normal hearing participated in the study. A sequence was presented to these subjects through a loudspeaker, the sequence included four blocks, a control block and three oddball blocks. The control block was made up of five components (one pure tone and four Chinese tones) with equiprobability. The oddball blocks were made up of two components, one was a standard stimulus (tone 1) and the other was a deviant stimulus (tone 2 or tone 3 or tone 4). Electroencephalogram (EEG) data were recorded when the sequence was presented and MMNs were obtained from the analysis of the EEG data. RESULTS: Two kinds of MMNs were obtained, oddball MMN and control MMN. Oddball MMN was obtained by subtracting the ERP elicited by standard stimulation (tone 1) from that elicited by deviant stimulation (tone 2 or tone 3 or tone 4) in the oddball block; control MMN was obtained by subtracting the ERP elicited by the tone in control block, which was the same tone as the deviant stimulation in the oddball block, from the ERP elicited by deviant stimulation (tone 2 or tone 3 or tone 4) in the oddball block. There were two negative waves in oddball MMN, one appeared around 150 ms (oddball MMN 1), the other around 300 ms (oddball MMN 2). Only one negative wave appeared around 300 ms in control MMN, which was corresponding to the oddball MMN 2. We performed the statistical analyses in each paradigm for latencies and amplitudes for oddball MMN 2 in discriminating the three Chinese tones and reported no significant differences. But the latencies and amplitudes for control MMN in discriminating the three tones all were significantly different. CONCLUSIONS: There are evident waveforms for oddball and control MMN obtained in normal hearing persons, indicating that the change of Chinese tones could be detected in the pre-attentive stage. Because control MMN can eliminate reflects for physical characteristics of sound, it is the genuine memory-based pre-attentive processing. Since control MMN can reflect the differences of Chinese tones processing better than oddball MMN, it is more sensitive in evaluating pre-attentive processing in Chinese tones discrimination.

[Establishment and rudimentary application of the method of recording auditory brainstem responses electrically stimulated via round-window niche in cochlear implants].

OBJECTIVE: To establish the method of recording auditory brainstem responses electrically stimulated via round-window niche in cochlear implants. METHODS: Self-made platinum iridium alloy as a spherical electrode stimulation electrode, modified cochlear implants connected to in vitro speech processor as a electro-stimulator and evoke potential instrument for Bio-logic Navigator Pro, 17 cochlear implant patients with various ages and of different causes, including auditory neuropathy (2 cases), ossified cochlea (1 case), inner ear malformation (5 cases), leukodystrophy (1 case), unknown and reason (8 cases) were investigated during cochlear implant surgery. Before cochlear implantation, stimulation electrode was placed in the round-window niche while charge balanced biphasic constant current was used as electrical stimulation via round window niche, and then electrically evoked auditory brainstem response was recorded. RESULTS: Electrically evoked auditory brainstem response waveforms were clearly recorded in all 17 cases. The latencies of III and V waves were (2.12 +/- 0.18) ms and (4.18 +/- 0.19) ms respectively, with threshold as (220.0 +/- 16.04) CL. The waveforms of the 2 patients with auditory neuropathy, 5 patients with inner ear malformation, 1 patient with ossified cochlea and 1 patient with leukodystrophy were well differentiated. CONCLUSIONS: Monitoring electrically evoked auditory brainstem response was an objective nerve electrophysiological testing method that accurately reflects function completeness of auditory pathway. It had important value for helping making the judgment whether patients could acquire auditory response after cochlear implantation. This method was safe and gave high emission of auditory response, therefore should be spread widely.

[Local response caused by implant after cochlear implantation].

OBJECTIVE: To approach the incidence rate, symptoms, etiologies, correlating reasons, consequences and treatments of local responses caused by implant after cochlear implantation and to provide reference for the future works. METHODS: From 1995 to 2007 there were 997 cases adopted cochlear implantation in Peding Union Medical College Hospital. Ten cases experienced local responses were analyzed retrospectively. RESULTS: The incidence of local response was 1.003%. There were 6 males and 4 females. The ages were between 13 months to 8 years old. The average age was 34 months. The devices mainly were made by Cochlear and Med-EL companies. The mainly symptoms and signs were local swellings, complaint of pruritus after ear, decrease of sound legibility and so on. Onset frequencies of this disease was 1 to 8 times. The bacterium cultured of displacing liquids was negative. But the IgE was detected in 2 cases. Results showed the patients were midrange status of hypersensitivity. Positive conservative treatments must be done including antibiotics, antihistamines, necessarily using immunotherapy. CONCLUSIONS: Besides local infection of bacteria, the allergy caused by silicone of implant coupled be a reason. Although the diagnose of this disease was difficult, but the screening of source of hypersensitivity was necessary before operation. It was recurrent attacks and maybe liable by kindred patients. Onset age was more below 4 years old. The patch test should be done again when the symptoms were occurrence after operation. If severe secondary infection was occurred and the states could not be well controlled the devices in the body must be explanted immediately. When the conditions were stable reimplantation could be experienced by non-sensibilisinogen devices.

Speech recognition and temporal amplitude modulation processing by Mandarin-speaking cochlear implant users.

OBJECTIVES: Fundamental frequency (F0) information is important to Chinese tone and speech recognition. Cochlear implant (CI) speech processors typically provide limited F0 information via temporal envelopes delivered to stimulating electrodes. Previous studies have shown that English-speaking CI users' speech performance is correlated with amplitude modulation detection thresholds (AMDTs). The present study investigated whether Chinese-speaking CI users' speech performance (especially tone recognition) is correlated with temporal processing capabilities. DESIGN: Chinese tone, vowel, consonant, and sentence recognition were measured in 10 native Mandarin-speaking CI users via clinically assigned speech processors. AMDTs were measured in the same subjects for 20- and 100-Hz amplitude modulated (AM) stimuli presented to a middle electrode at five stimulation levels that spanned the dynamic range. To further investigate the CI users' sensitivity to temporal envelope cues, AM frequency discrimination thresholds (AMFDTs) were measured for two standard AM frequencies (50 and 100 Hz), presented to the same middle electrode at 30% and 70% dynamic range with a fixed modulation depth (50%). RESULTS: Results showed that AMDTs significantly improved with increasing stimulation level and that individual subjects exhibited markedly different AMDT functions. AMFDTs also improved with increasing stimulation level and were better with the 100-Hz standard AM frequency than with the 50-Hz standard AM frequency. Statistical analyses revealed that both mean AMDTs (averaged for 20- or 100-Hz AM across all stimulation levels) and mean AMFDTs (averaged for the 50-Hz standard AM frequency across both stimulation levels) were significantly correlated with tone, consonant, and sentence recognition scores, but not with vowel recognition scores. Mean AMDTs were also significantly correlated with mean AMFDTs. CONCLUSIONS: These preliminary results, obtained from a limited number of subjects, demonstrate the importance of temporal processing to CI speech recognition. The results further suggest that CI users' Chinese tone and speech recognition may be improved by enhancing temporal envelope cues delivered by speech processing algorithms.

[Analysis of genetic mutation in patients with nonsyndromic hearing loss received cochlear implant].

OBJECTIVE: To investigate the prevalence of mutations of the gap junction protein (GJB) 2 and mitochondria 12SrRNA in patients with nonsyndromic hearing loss who received cochlear implant. METHODS: Genomic DNA was extracted from the peripheral blood samples obtained from 100 Chinese patients who had received cochlear implantation, 96 with prelingual hearing loss and 4 with postlingual hearing loss, all very severe. Sixteen of the 100 patients had the history of application of aminoglycosides, among which 12 were with prelingual hearing loss and 4 with postlingual hearing loss. PCR was performed and the products were sequenced by automated DNA sequencer. RESULTS: GJB2 mutations were detected in 34 of the 100 cochlear implant recipients (34%), all with prelingual hearing loss, among which 27 (27%) had 235delC mutation. Among the 16 patients who had used aminoglycosides, two had the mutation A1555G, and one carried the mitochondrial genetic mutation delT961Cn. CONCLUSION: Mutation of GJB2 gene is the major cause of deafness in cochlear implant recipients, with a high frequency of 235delC mutation. Mitochondria genetic mutation A1555G is the common form of mutation in postlingual deafness with a history of aminoglycoside injection.

[Screening of SLC26A4 (PDS) gene mutation in cochlear implant recipients with inner ear malformation].

OBJECTIVE: To determine the prevalence of SLC26A4 (PDS) gene mutations in cochlear implant recipients with inner ear malformation, and the correlation between SLC26A4 (PDS) gene mutation and inner ear malformation and intra-operative testing of the electrically evoked auditory nerve compound action potentials (ECAP). METHODS: Peripheral blood samples were collected from 48 cochlear implant recipients with temporal bone malformation and 50 healthy controls. Genomic DNA was extracted from the blood; PCR and direct sequencing were used to detect the mutations of SLC26A4 (PDS) gene. During the implantation of artificial cochlea the 48 recipients underwent intraoperative neural response telemetry (NRT) to measure the electrically evoked auditory nerve compound action potentials (ECAP). RESULTS: SLC26A4 (PDS) mutations were detected in 70.3% (26/37) of the patients with enlarged vestibular aqueduct (EVA), and 18.2% (2/11) of the patients with other malformations of inner ear. Fifteen different mutations were identified, 8 of which had never been previously reported. The IVS7-2A>G mutation was the most prevalent mutation of SLC26A4 (PDS) gene, accounting for 45.9% (17/37) in the EVA patients. No association was detected between SLC26A4 mutation and ECAP. CONCLUSION: Mutations in the SLC26A4 (PDS) gene is a major cause of EVA, with IVS7-2A>G as the most common mutation form.

Cochlear function after selective spiral ganglion cells degeneration induced by ouabain.

BACKGROUND: Ouabain, a cardiac glycoside that specifically binds to Na/K-ATPase and inhibits its activity, was applied to gerbils to develop a method for studying auditory neuropathy. METHODS: Ouabain was applied to the round window of the cochlea in each gerbil by using a piece of gelfoam with 3 microl or 24 microl (1 mmol/L) ouabain solution. The changes of the threshold of auditory brainstem response, cochlear function round window electrocochleography, as well as the morphological changes of the spiral ganglion cells of the cochlea were observed after application of ouabain for 24 hours or 96 hours. RESULTS: In ouabain treated gerbils, auditory brainstem response and compound action potential thresholds showed either elevation or no response at all. However, the thresholds of cochlear microphonic and distortion product otoacoustic emissions were not affected. Degeneration and necrosis of some spiral ganglion cells in ears with applications of ouabain (24 hours, 3 microl, 1 mmol/L; 96 hours, 24 microl, 1 mmol/L ouabain). The number of spiral ganglion cells was decreased (24 hours, 3 microl, 1 mmol/L ouabain) or near to a total loss (96 hours, 24 microl, 1 mmol/L ouabain). CONCLUSIONS: These results indicate a high degree of independence between the spiral ganglion cells and the outer hair cell systems in the cochlear transduction mechanism. The method used in this study would provide a valuable tool for studying auditory neuropathy.

[Cochlear implantation in patients with ossified cochleas].

OBJECTIVE: The ossified cochlea was no longer an absolute contra-indication to cochlear implantation but it was still a challenge even for the experienced otologist. To report the condition of cochlear implantation and the hearing results of 31 cases of cochlear ossification. METHODS: Retrospective analysis of cochlear implantation of 720 cases of cochlear implantation from May 1995 to July 2005 in Peking Union Medical College Hospital. RESULTS: Thirty-one cochlear ossification patients was found from all the 720 surgeries which included 27 mild cases and 4 severe ones, 14 males, 17 females. And the age of operation was 1. 4 - 59. 0 years old , mean age was 13. 2 years old. All of them had cochlear implanted through mastoid-facial recess. There was no complications during or post the operations. And the hearing threshold was about 40 dB in the sound field, the results were similar to those without cochlear ossification. CONCLUSIONS: Although it was difficult of cochlear implantation in cochlear ossification patients, but in most cases especially mild ones all the electrodes could be implanted after clearing the ossified tissue, and had few damage to the electrodes. Now it was possible to practice in the partial cochlea ossification.

[Cochlear implantation in patients with otitis media-related diseases].

OBJECTIVE: To evaluate the indications, surgical techniques and complications of cochlear implantation in patients with otitis media-related diseases. METHODS: Retrospective study of the data collected from patients receiving cochlear implantation. Totally 866 cases of cochlear implantation were performed in Peking Union Medical College Hospital from May 1995 to February 2006. Among which, 41 patients with otitis media-related diseases were grouped into 5 types: chronic secretory otitis media (13 cases), silent (subclinical) otitis media (18 cases), dry eardrum perforation (1 case), bilateral cholesteatoma of middle ear (2 cases) and middle ear granuloma (7 cases). Seven cases were accompanied with deformities of middle ear and (or) inner ear. Pedicled aponeurosis of occipitofrontalis muscle was transplanted to cover and protect the inserted electrodes and facial nerve in a patient with bilateral cholesteatoma after radical mastoidectomy. RESULTS: All the 41 patients with otitis media-related diseases were successfully implanted in one stage or staged operations and followed up uneventfully for 5 months to 6 years and 11 months. All implant devices had worked normally and all patients had performed well. CONCLUSIONS: Patients with chronic secretory otitis media, silent (subclinical) otitis media, middle ear granuloma or dry ear-drum perforation could be operated in one stage or staged procedures safely and effectively. Patients with bilateral cholesteatoma could be implanted after radical removal of related lesions. Pedicled aponeurosis of occipitofrontalis muscle could be transplanted in cases of mastoid bowl to cover and protect the inserted electrodes and the exposed facial nerve and with easy access to observe the mastoid cavity. Active suppurative otitis media was contraindicated for cochlear implantation. Long-term following-up was essential for better evaluation of the outcomes of cochlear implantation in patients with otitis media-related diseases.

[High prevalence of connexin-26 (GJB2) mutation in cochlear implant recipients].

OBJECTIVE: To determine the prevalence of GJB2 gene mutations in patients undergoing cochlear implantation. METHODS: We enrolled 115 cochlear implant recipients for mutation screening. Genomic DNA was extracted from the blood of all patients, amplified in PCR and analyzed for single strand conformation polymorphism (SSCP) or direct sequencing to detect mutations of GJB2 gene. RESULTS: The result shows that the GJB2 mutations are detected in 36.5% (42/115) of the cochlear implant recipients, and especially 41% (41/100) of the non-syndromic deafness patients, only 1 inner ear malformation patient was detected with GJB2 mutations. This study found 11 different variations in the GJB2 gene. The 235delC mutation was the most prevalent mutation accounting for 18.3% (41/230) in all cochlear implant recipients and 21% (42/200) in non-syndromic deafness group. 187G > T and 230G > A mutations were novel mutation of GJB2 gene in the Chinese population. CONCLUSION: Mutations in the GJB2 gene were a major cause of deafness in cochlear implant recipients, the carrier frequency of 235delC mutation was highest.

[Voice analysis in pre-lingual cochlear implant adults].

OBJECTIVE: To observe voice characteristic of pre-lingual cochlear implant adults for cochlear implantation and phoniatrics. METHODS: 3s-sustained voice of vowel [ a: ] of 28 pre-lingual cochlear implant adults, 18 pre-lingual deafness adults and 10 adults with normal hearing were analyzed. Specifically, the Voice analyses include fundamental frequency, first formant, second formant, frequency perturbation quotient (FPQ), amplitude perturbation quotient (APQ) and harmonic noise ratio (HNR). The outcomes of 3 groups were compared. RESULTS: The fundamental frequency was lower in cochlear implant group [(175.42+/-25. 31) Hz] than that in deafness group [(210.84+/-54.300) Hz] (P = 0.02). The position of formant of cochlear implant group [F2 = (1264. 64 +/- 152.19) Hz] was more access to normal than that of normal hearing group[ F2 = (1422.44 +/- 232. 37) Hz, P = 0. 02]. FPQ of cochlear implant group (2.09 +/- 1.15) was more access to normal than that of deafness group (5.32+/-4.29, P=0.006). The voice of cochlear implanted and deafness adults were much more different individually. CONCLUSIONS: In the aspect of acoustic characteristic of voice, pre-lingual cochlear implant adults could benefit cochlear implantation finitely. As speech perception of pre-lingual cochlear implant adults was far worse than that of children and post-lingual cochlear implant adults, the general outcome of pre-lingual cochlear implant adults was very limited. Cochlear implant of those candidate should be cautious.