Background: The GJB2 gene, mapping to chromosome 13q12, encodes a gap junction protein, connexin 26, and is responsible for certain forms of congenital deafness, such as DFNB1 and DFNA3. Mutations of this gene are responsible for about one half of severe autosomal recessive non-syndromic deafness. Methods: To determine whether GJB2 mutations are major causes of deafness in Chinese cochlear implant recipients, we enrolled 115 cochlear implant recipients for mutation screening. Results: The results showed that 36.5% (42/115) of all cochlear implant recipients and 41% (41/100) of non-syndromic deafness patients exhibit GJB2 mutations; only 1 inner ear malformation patient was detected with GJB2 mutations. The present study found 11 different variations in the GJB2 gene. Conclusion: The 235delC mutation was the most prevalent mutation, found in 18.3% (42/230 alleles) of all cochlear implant recipients and 21.0% (42/200 alleles) of the non-syndromic deafness group. Only 0.6% of GJB2 mutations were detected in the inner ear malformation group. The novel 187G→T mutations are likely to be pathological mutations.

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.

Objective: The present study was aimed to examine the relationship between psychophysical performance in temporal and spectral resolution and Mandarin tone recognition in noise by cochlear-implant (CI) listeners. Design: Seventeen Nucleus-24 implant users, 10 postlingually deafened and 7 prelingually deafened, participated in the experiments. A 3-interval, forced-choice procedure was used to measure gap detection and pure-tone frequency discrimination at 250 to 4,000 Hz in octave steps. A 4-alternative forced-choice procedure was used to measure Mandarin tone recognition in quiet and in noise. Signal-to-noise ratios (SNRs) varied from +10 to –10 dB. All stimuli were delivered to the clinical processor via a speaker in a sound free field. The obtained data were compared to data collected from normal-hearing control subjects, as well as cochlear-implant users who performed similar tasks using single-electrode stimulation via a research interface. Results: Postlingually-deafened CI subjects generally performed better than prelingually-deafened subjects. The average gap detection threshold was 30 ms with a range from 4 to 128 ms. The average frequency difference limen was 100 Hz with a range from 12 to 192 Hz, regardless of the standard frequency. The average tone recognition was 80% correct in quiet, which dropped to 55% at +10 dB SNR and essentially chance performance at –5 dB SNR. In comparison, the normal-hearing control subjects maintained essentially perfect performance over this SNR range. Only frequency discrimination at 1,000 Hz was significantly correlated with tone recognition in quiet but all psychophysical measures were correlated to tone recognition in noise. Conclusions: The present result suggests that the CI users can rely on either temporal or spectral cues to perform tone recognition in quiet, but need both cues for tone recognition in noise. Future CI processors need to extract and encode these acoustic cues to achieve better performance in tone perception and production.

OBJECTIVETo summarize and analyze the etiology, surgical indications, operation methods and outcomes of cochlear implantation.METHODS533 cases (534 ears) with severe and profound hearing loss received cochlear implant, 489 were pre-lingual deafness and 38 cases were post-lingual deafness. Their ages at implant, 1 to approximately 3 were 167, approximately 5 were 77, approximately 7 were 73, approximately 14 were 136, approximately 17 were 28, >17 were 52. 76 cases (14. 3%) were found the middle and inner ear malformations. That included Mondini 26 in cases, Common cavity in 10 cases and Large vestibule aqueduct syndrome in 20 cases. The average pure tone threshold were 105.5 dB HL, ABR threshold were >95 dB nHL and 40 Hz threshold in 500 Hz were 101.7 dB. The devices they used were Nucleus 22M in 27 ears, 24M in 308 ears, 24R Contour in 131 ears and 24R ST in 21 ears; Med El C40+ in 44 ears; Clarion CI in 3 ears. Facial recess approach was performed in normal cases, and in Common cavity cases horizontal semicircular canal approach was used. Preoperative hearing and speech evaluations were done in most cases.RESULTSIn 26 Mondini case, gusher were happened in 20 cases. The insertion depth in normal cases: Nucleus were 30 bands, Med El were 31 mm. In Mondini cases, Nucleus were 28 bands. In Common cavity cases, Nucleus were 26 bands. Of 533 cases, The average of open set sentences discrimination of post-lingual deafness was 70%, the satisfaction rate of questionnaire for pre-lingual deafness under 17 years old was 94.7%.CONCLUSIONSCochlear implant is a useful method to restore the hearing of the patients with severe and profound hearing loss. It is important for the outcomes with proper preoperative assessment, surgery and postoperative speech and hearing evaluations.

OBJECTIVE:To investigate tone recognition and electrode discrimination in prelingually deafened children with the Nucleus device, and to develop guidelines for customized mapping in the implant users.METHODS:Fourteen prelingually deafened children with cochlear implants participated in this study. Tone recognition was measured with a four-alternative, forced choice procedure from 25 consonant-vowel syllables, each of which had four tonal variations. Electrode discrimination was measured using a same-difference procedure on 7 pairs of electrodes covering the entire electrode array.RESULTS:Tone recognition ranged from 35% to 99% correct with a mean of 62.8% and standard deviation of 14.7% in these users. Electrode discrimination had the mean threshold of 3.4 +/- 0.9, with the best performance from the middle electrodes (E 14 and E 17) at 2.6 and the followed performance at the most apical electrode (E 20).CONCLUSION:The results showed significant individual differences from both tone recognition and electrode discrimination, but there is significant correlation between them.

OBJECTIVE:To investigate the attenuation of cisplatin-induced toxicity in the spiral ganglion neuron (SGNC) by the localized expression of the neurotrophin-3 (NT-3) and glial cell line-derived nerutrophic factor (GDNF) via HSV-Amplicon.METHODS:We constructed the HSV-Amplicon vectors, which could express the NT-3 and GDNF under separate transcriptional control. Helper virus-free amplicon stocks were assessed in vitro for their capacity in the cultured inner ear cells. The ELISA was used to detect the production of NT-3 and GDNF. Three groups of mice were injected with cisplatin (8 mg/kg), followed by instillation of HSVnt-3myc/gdnf, HSVnt-3myc/lac or HSVlac. The numbers of SGNC were analyzed 4 weeks later.RESULTS:The HSVnt-3myc/gdnf transduction resulted in production of NT-3 up to 11.44 micro g/ml and GDNF up to 1.79 ng/ml in cultured medium over 48 h. There were significant differences among three groups (P < 0.01). Cochleae transduced with HSVnt-3myc/gdnf and HSVnt-3myc/lac harbored from the mice had greater number of surviving SGNC. The ratio of SGNC survival (%) in HSVnt-3myc/gdnf, HSVnt-3myc/lac and HSVlac was 88%, 77% and 22%, respectively.CONCLUSION:The transduction of NT-3/GDNF by HSV-Amplicon greatly attenuated SGNC the cisplatin-induced ototoxicity in mice.