Electrococleografía en implante coclear / Electrocochleography in cochlear implant

La electrococleografía es una técnica electrofisiológica desarrollada en modelos animales hace más de 90 años. En la actualidad se utiliza en la práctica clínica en audiolo-gía y otoneurología, ya que permite evaluar la función coclear, a través del registro del potencial microfónico coclear, y la funcionalidad del nervio auditivo por medio del registro del potencial de acción compuesto. Debido al avance de la tecnología de los implantes cocleares, actualmente existe la posibilidad de realizar mediciones clínicas a tiempo real con electrococleografía intraoperatoria, por lo que se puede monitorizar la función auditiva residual durante la inserción de los electrodos del implante coclear. En este artículo se presenta una revisión narrativa del uso y aplicación clínica de la electrococleografía en la evaluación de pacientes con implante coclear para predecir el desempeño auditivo y la percepción del habla. La literatura muestra que la electroco-cleografía es una técnica que se encuentra, plenamente, vigente para evaluar la función auditiva en pacientes usuarios de implantes cocleares. Si bien las respuestas cocleares han demostrado ser un buen predictor de los umbrales perceptuales auditivos y del habla en silencio en adultos, aún es una técnica que requiere más desarrollo para ser una herramienta clínica que permita predecir el habla en ruido y la función auditiva en niños y adultos mayores.

Electrocochleography is an electrophysiological technique developed in animal models more than 90 years ago. It is currently used in clinical practice in audiology and otoneurology, since it allows the evaluation of cochlear function, through the recording of the cochlear microphonic potentials, and the functionality of the auditory nerve by means of compound action potential recordings. Due to the advancement of cochlear implant technology, there is currently the possibility of real-time clinical measurements with intraoperative electrocochleography, so that residual hearing function can be monitored during the insertion of the cochlear implant electrodes. This article presents a narrative review of the use and clinical application of electrocochleography in the evaluation of patients with cochlear implants to predict auditory performance and speech perception. The literature shows that electrocochleography is a technique that is fully in force to assess hearing function in patients who use cochlear implants. Although cochlear responses have been shown to be a good predictor of auditory perceptual thresholds and speech in quiet in adults, it is still a technique that requires further development to become a clinical tool for predicting speech in noise and auditory function in children and older adults.

Application of cochlear nerve action potential monitoring in the resection of vestibular schwannomas / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the application of cochlear nerve action potential (CNAP) monitoring in the resection of vestibular schwannoma, especially evaluating its significance for hearing preservation. Methods: From April 2018 to December 2021, 54 patients with vestibular schwannoma who underwent resection via retrosigmoid approach were collected in Chinese PLA General Hospital. Before surgery, all patients had effective hearing (AAO-HNS grade C or above). Brainstem auditory evoked potential (BAEP) combined with CNAP monitoring was performed during surgery. The CNAP monitoring was combined with continuous monitoring and cochlear nerve mapping. And patients were divided into hearing preservation group and non-preserved group according to postoperative AAO-HNS grade. SPSS 23.0 software was used to analyze the differences of CNAP and BEAP parameters between the two groups. Results: A total of 54 patients completed intraoperative monitoring and data collection, including 25 males (46.3%) and 29 females (53.7%), aged 27-71 years with an average age of 46.2 years. The maximum tumor diameter were (18.1±5.9) mm (range 10-34 mm). All tumors were totally removed with preserved facial nerve function (House-Brackmann grade I-II). The hearing preservation rate of 54 patients was 51.9% (28/54). During surgery, the V wave extraction rate of BAEP waveform was 85.2% (46/54) before tumor resection, 71.4% (20/28) in the hearing preservation group after tumor resection, and disappeared in the hearing preservation group (0/26). CNAP waveform was elicited in 54 patients during operation. Differences were found in the distribution of CNAP waveforms after tumor resection. The waveforms of the hearing-preserving group were triphasic and biphasic, while those in the non-preserving group were low-level and positive. For hearing preservation group, the amplitude of N1 wave after tumor resection was significantly higher than that before tumor resection[14.45(7.54, 33.85)μV vs 9.13(4.88, 23.35)μV, P=0.022]; However, for the non-preserved group, the amplitude of N1 wave after tumor resection was significantly lower than that before tumor resection [3.07(1.96, 4.60)μV vs 6.55(4.54, 9.71)μV, P=0.007]; After tumor resection, the amplitude was significantly higher than that of the unreserved group [14.45(7.54, 33.85)μV vs 3.07(1.96, 4.60)μV, P<0.001]. Conclusions: BAEP combined with CNAP monitoring is conducive to intraoperative hearing protection, and the application of cochlear nerve mapping can prompt the surgeon to avoid nerve injury. The waveform and N1 amplitude of CNAP after tumor resection have a certain value in predicting postoperative hearing preservation status.

Characteristics of responsiveness of cochlear nerve to electrical stimulation in patients with cochlear nerve deficiency / 中华耳鼻咽喉头颈外科杂志

Objectives: This study aimed to evaluate the responsiveness of cochlear nerve to electrical stimulation in patients with cochlear nerve deficiency(CND), to compare their results with those measured in implanted children with normal-sized cochlear nerves, and to investigate the characteristics of the cochlear nerve injury of children with CND. Methods: Participants were children who underwent cochlear implantation at Shandong Provincial ENT Hospital from January 2012 to January 2020, including CND group and control group. The CND group included 51 subjects (male:20; female: 31) who were diagnosed with CND and had normal cochlea. For the CND group, four children had been bilaterally implanted, the mean implantation age was (2.7±1.5) years old. The control group included 21 subjects (male:10; femal:11) who had normal-sized cochlear nerve and normal cochlea. For the control group, all children had been unilaterally implanted except one, and the mean implantation age was (3.0±1.9)years old. Three subjects in the CND group used CI422 electrode arrays, and all the other subjects used CI24RECA/CI512 electrode arrays. The electrically evoked compound action potentials (ECAP) had been tried to record for each electrode using Custom Sound EP software (v. 4.3, Cochlear Ltd.) at least six months post first activation. Furthermore, ECAP amplitude growth functions (AGF) were measured at multiple electrode locations across the electrode array. Generalized linear mixed effect models with the subject group and electrode location as the fixed effects and subjects as the random effect were used to compare results of ECAP measurements. Results: In the control group, ECAP could been recorded at all electrodes (100%), but it could only be recorded in 71% (859/1 210) electrodes in the CND group. Additionally, the percentage of electrodes with measurable ECAP decreased from electrode 1 to electrode 22 in the CND group. Compared to the control group, the ECAP thresholds significantly increased, the ECAP amplitudes and AGF slopes significantly decreased, and the ECAP latency significantly increased in the CND group (P<0.01). GLMM showed that the stimulating site had a significant effect on the ECAP threshold, maximum amplitude, and AGF slope (P<0.01), but had no significant effect on the ECAP latency (P>0.05) in the CND group. However, the stimulating site had no significant effects on the ECAP measurements in the control group. Furthermore, the functional status of cochlear nerve varied greatly among CND group. From electrode 1 to electrode 22, the ECAP thresholds gradually increased, the ECAP maximum amplitudes and AGF slopes gradually decreased in the CND group. Conclusion: Compared with patients with normal-sized cochlear nerve, not only the number of residual spinal ganglion neurons reduce,but also the function of spinal ganglion neurons damages in CND patients. The degree of cochlea nerve deterioration varies greatly among CND patients. Generally, the deterioration of cochlear nerve tends to increase from the basal to the apical site of the cochlea.

Application of intraoperative CT-assisted positioning in difficult cases of cochlear implantation / 临床耳鼻咽喉头颈外科杂志

Objective:To report the experience of using CT-guided cochlear implant surgery in difficult cases such as severe inner ear deformities and anatomical abnormalities, and to discuss the application value of intraoperative CT-assisted localization in difficult cases of cochlear implant surgery. Methods:Retrospectively analyzed the clinical data of 23 cases of difficult cochlear implant surgery cases completed by our team with the assistance of intraoperative CT, and collected their medical data, including preoperative imaging manifestations, surgical conditions, and intraoperative imaging images for evaluation. Results:During the study period, 23 difficult cases（27 ears） underwent cochlear implantation under the guidance of intraoperative CT, and 4 cases were bilaterally implanted. Including 6 cases of incomplete segmentation type Ⅰ（IP-Ⅰ）, 1 case of incomplete segmentation type Ⅱ（IP-Ⅱ）, 10 cases of incomplete segmentation type Ⅲ（IP-Ⅲ）, 3 cases of common cavity deformity（CC） and 3 cases of cochlear ossification after meningitis. Facial nerve anatomy was abnormal in 9 cases, cerebrospinal fluid "blowout" was serious in 14 cases, electrode position was abnormal in 3 cases requiring intraoperative adjustment of electrode position, anatomical difficulties required intraoperative CT to assist in finding anatomical landmarks in 2 cases, and electrodes were not fully implanted in 3 cases. Conclusion:When faced with difficult cases with challenging and complex temporal bone anatomy, intraoperative CT can accurately evaluate the electrode position and provide intraoperative anatomical details, allowing immediate adjustment of the electrode position if necessary, providing safety guarantee for difficult cases of cochlear implant surgery and ensure accurate implantation of electrodes.

Cochlear electrode array misplacement into the superior semicircular canal: a case report and literature review / 临床耳鼻咽喉头颈外科杂志

Electrode array misplacement is a rare complication of cochlear implant. This article reports an 11-year-old boy who was mistakenly implanted the cochlear electrode array into the superior semicircular canal during the initial cochlear implant. After the diagnosis was confirmed, he underwent a second cochlear implant and the electrode array were successfully implanted into the cochlea. This article conducted a systematic review of the literature on electrode array misplacement, and the causes of electrode array misplacement were analyzed from different implantation position.

Single-cell transcriptomic atlas of mouse cochlear aging

Progressive functional deterioration in the cochlea is associated with age-related hearing loss (ARHL). However, the cellular and molecular basis underlying cochlear aging remains largely unknown. Here, we established a dynamic single-cell transcriptomic landscape of mouse cochlear aging, in which we characterized aging-associated transcriptomic changes in 27 different cochlear cell types across five different time points. Overall, our analysis pinpoints loss of proteostasis and elevated apoptosis as the hallmark features of cochlear aging, highlights unexpected age-related transcriptional fluctuations in intermediate cells localized in the stria vascularis (SV) and demonstrates that upregulation of endoplasmic reticulum (ER) chaperon protein HSP90AA1 mitigates ER stress-induced damages associated with aging. Our work suggests that targeting unfolded protein response pathways may help alleviate aging-related SV atrophy and hence delay the progression of ARHL.

Aligned Organization of Synapses and Mitochondria in Auditory Hair Cells / 神经科学通报·英文版

Recent studies have revealed great functional and structural heterogeneity in the ribbon-type synapses at the basolateral pole of the isopotential inner hair cell (IHC). This feature is believed to be critical for audition over a wide dynamic range, but whether the spatial gradient of ribbon morphology is fine-tuned in each IHC and how the mitochondrial network is organized to meet local energy demands of synaptic transmission remain unclear. By means of three-dimensional electron microscopy and artificial intelligence-based algorithms, we demonstrated the cell-wide structural quantification of ribbons and mitochondria in mature mid-cochlear IHCs of mice. We found that adjacent IHCs in staggered pairs differ substantially in cell body shape and ribbon morphology gradient as well as mitochondrial organization. Moreover, our analysis argues for a location-specific arrangement of correlated ribbon and mitochondrial function at the basolateral IHC pole.

The complete and two-turn cochlear duct length among Filipinos

Objective@#This study aims to measure the complete and two-turn cochlear duct lengths in a Filipino population using archived CT scan images.

Preliminary observation on the differential expression of metformin in preventing noise-induced hearing loss in inner ear protein group of rats / 中华劳动卫生职业病杂志

Objective: To study the protective effects of metformin on noise-induced hearing loss (NIHL) and its differential protein omics expression profile. Methods: In January 2021, 39 male Wistar rats were randomly divided into control group, noise exposure group and metformin+noise exposure group, with 13 rats in each group. Rats in the noise exposure group and metformin+noise exposure group were continuously exposed to octave noise with sound pressure level of 120 dB (A) and center frequency of 8 kHz for 4 h. Rats in the metformin+noise exposure group were treated with 200 mg/kg/d metformin 3 d before noise exposure for a total of 7 d. Auditory brainstem response (ABR) was used to test the changes of hearing thresholds before noise exposure and 1, 4, 7 d after noise exposure in the right ear of rats in each group. Tandem mass tag (TMT) quantitative proteomics was used to identify and analyze the differentially expressed protein in the inner ear of rats in each group, and it was verified by immunofluorescence staining with frozen sections. Results: The click-ABR thresholds of right ear in the noise exposure group and metformin+noise exposure group were significantly higher than those in the control group 1, 4, 7 d after noise exposure (P<0.05) . The click-ABR threshold of right ear in the metformin+noise exposure group were significantly lower than that in the noise exposure group (P<0.05) . Compared with the noise exposure group, 1035 up-regulated proteins and 1145 down-regulated proteins were differentially expressed in the metformin+noise exposure group. GO enrichment analysis showed that the significantly differentially expressed proteins were mainly involved in binding, molecular function regulation, signal transduction, and other functions. Enrichment analysis of KEGG pathway revealed that the pathways for significant enrichment of differentially expressed proteins included phosphatidylinositol 3-kinase-protein kinase B (PI3K-Akt) signaling pathway, focal adhesion, diabetic cardiomyopathy, mitogen, and mitogen-activated protein kinase (MAPK) signaling pathway. Immunofluorescence experiments showed that compared with the noise exposure group, the fluorescence intensity of insulin-like growth factor 1 receptor (IGF1R) in the metformin+noise exposure group was increased, and the fluorescence intensity of eukaryotic translation initiation factor 4E binding protein 1 (eIF4EBP1) was decreased. Conclusion: Noise exposure can lead to an increase in rat hearing threshold, and metformin can improve noise-induced hearing threshold abnormalities through multiple pathways and biological processes.

The Complete and two-turn cochlear duct length among Filipinos

Objective: This study aims to measure the complete and two-turn cochlear duct lengths in a Filipino population using archived CT scan images.Methods:                Design: Retrospective Review of Records               Setting: Tertiary Government Training Hospital               Participants: CT Scan Images of 255 patientsCochlear images of patients who underwent cranial, facial, orbital, paranasal sinus and temporal bone CT scans from January 2019 to December 2019 were analyzed. Coronal oblique images from 3D multiplanar reconstructions were obtained and a single linear measurement ('A' value) was used as the spiral coefficient to calculate the complete cochlear duct length (CDL) and two-turn length (2TL).Results: A total of 510 cochlear images were obtained from the CT scan images of 255 subjects (143 males, 112 females aged 1 to 81 years; mean age = 47 years). The mean 'A' value was 8.81 mm (SD = 0.20). The mean complete cochlear duct length was 32.68 mm (31.01 mm - 35.50 mm; SD = 0.834) while the mean two-turn cochlear duct length was 29.61 mm (28.14 mm - 32.08 mm; SD = 0.732). The complete and two-turn cochlear duct lengths in males were found to be significantly longer than in females (p = .001). No significant difference was found between cochlear measurements for left and right ears.Conclusion: The mean complete cochlear duct length among Filipinos in our study measures 32.68 mm while the mean two-turn cochlear duct length measures 29.61mm. Both complete and two-turn cochlear duct lengths were longer among Filipino males than among females.

Prestin-Mediated Frequency Selectivity Does not Cover Ultrahigh Frequencies in Mice / 神经科学通报·英文版

In mammals, the piezoelectric protein, Prestin, endows the outer hair cells (OHCs) with electromotility (eM), which confers the capacity to change cellular length in response to alterations in membrane potential. Together with basilar membrane resonance and possible stereociliary motility, Prestin-based OHC eM lays the foundation for enhancing cochlear sensitivity and frequency selectivity. However, it remains debatable whether Prestin contributes to ultrahigh-frequency hearing due to the intrinsic nature of the cell's low-pass features. The low-pass property of mouse OHC eM is based on the finding that eM magnitude dissipates within the frequency bandwidth of human speech. In this study, we examined the role of Prestin in sensing broad-range frequencies (4-80 kHz) in mice that use ultrasonic hearing and vocalization (to >100 kHz) for social communication. The audiometric measurements in mice showed that ablation of Prestin did not abolish hearing at frequencies >40 kHz. Acoustic associative behavior tests confirmed that Prestin-knockout mice can learn ultrahigh-frequency sound-coupled tasks, similar to control mice. Ex vivo cochlear Ca2+ imaging experiments demonstrated that without Prestin, the OHCs still exhibit ultrahigh-frequency transduction, which in contrast, can be abolished by a universal cation channel blocker, Gadolinium. In vivo salicylate treatment disrupts hearing at frequencies <40 kHz but not ultrahigh-frequency hearing. By pharmacogenetic manipulation, we showed that specific ablation of the OHCs largely abolished hearing at frequencies >40 kHz. These findings demonstrate that cochlear OHCs are the target cells that support ultrahigh-frequency transduction, which does not require Prestin.

Research progress of the regulation of cochlear sensitivity to noise by circadian rhythm / 生理学报

High level noise can damage cochlear hair cells, auditory nerve and synaptic connections between cochlear hair cells and auditory nerve, resulting in noise-induced hearing loss (NIHL). Recent studies have shown that animal cochleae have circadian rhythm, which makes them different in sensitivity to noise throughout the day. Cochlear circadian rhythm has a certain relationship with brain-derived neurotrophic factor and glucocorticoids, which affects the degree of hearing loss after exposure to noise. In this review, we summarize the research progress of the regulation of cochlear sensitivity to noise by circadian rhythm and prospect the future research direction.

Manejo del tinnitus con estimulador de sonido con especificidad frecuencial / Treatment of tinnitus with sound stimulator with frequency specificity

Introducción: el tinnitus tiene efectos deletéreos sobre la calidad de vida de un paciente. Cuando la lesión está a nivel coclear, se puede usar acondicionamiento acústico para su tratamiento. Objetivo: determinar el cambio en la percepción del tinnitus antes y después de la intervención terapéutica. Metodología: se planteó un estudio de serie de casos. Pacientes con tinnitus no pulsátil de moderado a catastrófico tratados con estimulador REVE 134™. Se incluyeron pacientes que no mejoraron luego de 3 meses con tratamiento médico. Se les practicó microaudiometría (67 frecuencias) para definir la región coclear afectada. Se excluyeron pacientes con umbrales audiométricos > 60 dB, aquellos con lesiones retrococleares y quienes no desearon participar. Las variables de desenlace fueron Tinnitus Handicap Inventory (THI), escala visual análoga (EVA) y Tinnitus Reaction Questionnaire (TQR), que se midieron pretratamiento y a los 3 y 6 meses postratamiento. Resultados: se incluyeron 11 pacientes (hombres = 5, mujeres = 6). En 5 casos el tinnitus fue bilateral y en 6, unilateral. Los valores pretratamiento fueron THI = 61,4 ± 27,4, EVA = 6,9 ± 2,7 y TQR = 43,2 ± 31,9 (Kolmogorov-Smirnov, p > 0,05). Hubo mejoría estadísticamente significativa con el tratamiento, THI (3 meses = 30,6 ± 21,1; 6 meses = 19 ± 19,2), EVA (3 meses = 5,6 ± 2,3; 6 meses = 3,5 ± 2,0), TQR (3 meses = 25,6 ± 20,0; 6 meses = 14,3 ± 19,9); ANOVA de medidas repetidas (p = 0,007, p = 0,027, p = 0,037; respectivamente). Conclusión: el tratamiento con REVE 134™ fue efectivo en pacientes con tinnitus no pulsátil de moderado a catastrófico.

Introduction: tinnitus can affect the quality of life of a patient. Acoustic stimulation can be used as treatment when the cause of tinnitus is located in the cochlea. Objective: To determine changes in tinnitus perception before and after therapeutic intervention. Methodology: We performed a case series study. Patients with nonpulsatile tinnitus, with no improvement with medical therapy, and moderate to catastrophic grade were treated with the REVE 134™ system. A microaudiometry (67 frequencies) was performed to determine the cochlear regions affected. Patients with auditory thresholds >60 dB, retrocochlear pathologies and who did not want to participate in the study were excluded. The variables studied were Tinnitus Handicap Inventory (THI), Visual Analog Scale (VAS) and Tinnitus Reaction Questionnaire (TQR), that were measured before, three and six months after treatment. Results: 11 patients (male: 5, women: 6) were included. In 5 of them, tinnitus was bilateral and in 6, unilateral. Pretreatment values were: THI = 61.4 ± 27.4, VAS = 6.9 ± 2.7 and TQR = 43.2 ± 31.9 (Kolmogorov-Smirnov, p > 0.05). We found improvement in tinnitus perception with the therapy, and this values had statistical significance (THI: 3rd month = 30.6 ± 21.1; 6th month = 19 ± 19.2), VAS (3rd month = 5.6 ± 2.3; 6th month = 3.5 ± 2.0), TQR (3rd month = 25.6 ± 20.0; 6th month =14.3 ± 19.9); repetitive measures of ANOVA (p = 0.007, p = 0.027, p = 0.037; respectively). Conclusion: Treatment with REVE 134™ was effective in patients with moderate to catastrophic tinnitus.

Cochlea cell-specific marker expression upon in vitro Hes1 knockdown

NOTCH pathway proteins, including the transcriptional factor HES1, play crucial roles in the development of the inner ear by means of the lateral inhibition mechanism, in which supporting cells have their phenotype preserved while they are prevented from becoming hair cells. Genetic manipulation of this pathway has been demonstrated to increase hair cell number. The present study aimed to investigate gene expression effects in hair cells and supporting cells after Hes1-shRNA lentivirus transduction in organotypic cultures of the organ of Corti from postnatal-day-3 mice. Forty-eight hours after in vitro knockdown, Hes1 gene expression was reduced at both mRNA and protein levels. Myo7a (hair cell marker) and Sox2 (progenitor cell marker) mRNA levels also significantly increased. The modulation of gene expression in the organ of Corti upon Hes1 knockdown is consistent with cell phenotypes related to lateral inhibition mechanism interference in the inner ear. The lentivirus-based expression of Hes1-shRNA is a valuable strategy for genetic interference in the organ of Corti and for future evaluation of its efficacy in protocols aiming at the regeneration of hair cells in vivo.

Design of Scalable Model of Cochlear Scala Tympani / 中国医疗器械杂志

For cochlear implant training and robotic cochlear implant experiments, the design method of scalable scala tympani model was proposed. The mathematical model of the cochlea was used as the central curve of scala tympani channel. Referring to the clinical anatomy data, the contour of the scala tympani cross-section was approximated as an ellipse. The profile was placed along the central curve, and the angle was adjusted to determine the position and orientation of the profile in three dimensions such that the central curve passes through its center. The data was imported into Matlab to generate a three-dimensional mathematical model of scala tympani, which can be expanded by setting different scale factors. The virtual scala tympani model was generated in SolidWorks, and the 2:1 fully transparent scala tympani model were fabricated by 3D printing to replace the specimen for experiment.

The effect of large-conductance calcium-activated potassium channels on the migration of pericytes in the mice of senile cochlear stria vascularis / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate whether large conductance calcium-activated potassium channel (BK(Ca)) was involved in the migration of pericytes (PC) in the mice of senile cochlear stria vascularis capillaries PC. Methods: C57BL/6J mice were divided into 3-month (n=10) and 12-month groups (n=10). Auditory brainstem response (ABR) was used to test the hearing threshold of each group. The immunofluorescence was used to detect the expression changes of osteopontin (OPN) and β-BK(Ca) channels on cochlear stria vascularis PC. The morphological changes of perivascular cells in cochlea were observed by transmission electron microscope (TEM). Cell experiment: The PC, which were in the stria vascularis of the cochlea were primary cultured and identified. A cell senile model was made with D-gal. The appropriate intervention concentration of low galactose (D-gal) was determined by CCK8. β-galactosidase (SA-β-gal) staining was used to evaluate the cell decrept level. The change of BK(Ca) channels current on PC were recorded by whole cell patch clamp technique. The expression of BK(Ca) channels on PC was detected by immunofluorescence. The migration and invasion ability of two groups were detected by using Scratch test and Transwell. The levels of OPN and β-BK(Ca) channels were detected by Western blot. SPSS 22.0 software was used to analyze the data. Results: The ABR threshold in the 12-month group was higher than 3-month group (t=12.66, P<0.01). In the 12-month group, the expression of β-BK(Ca) channel was lower and the expression of OPN was increased (t=14.64, P<0.01; t=20.73, P<0.01). In TEM, cochlear stria vascularis PC were tightly connected to endothelial cells in 3-month group, while PC were loosely connected to endothelial cells or PC soma were separated from the capillary in 12-month group. Cell experiment: The positive rate of PC in the primary cultured cochlear stria vascularis is above 95%. Compared with the SA-β-gal stained cells in the control group, the positive rate of 15 mg/ml D-gal intervention PC was 85% (t=36.90, P<0.01). Whole cell patch clamp BK(Ca) channels current decreased in the D-gal group compared with the young group PC (t=12.18, P<0.05). The OPN expression in the senile group was higher than control group (t=16.30, P<0.01), while the β-BK(Ca) channels expression was decreased (t=11.98, P<0.01; t=15.72, P<0.05), and migration ability raised (t=7.91, P<0.01;t=7.59, P<0.01). After intervened of BK(Ca) channels specific blocker IBTX in the D-gal group, the expression of OPN and migration were increased (t=4.26, P<0.05; t=5.88, P<0.01; t=21.97, P<0.01). Conclusion: PC migration capacity were increased during the senile period, and the expression of β-BK(Ca) channel was decreased. The administration of IBTX, a specific blocker of BK(Ca) channel, at the cell level could increase the migration capacity, suggesting that BK(Ca) might be involved in the migration of PC in the stria vascularis of the aging cochlea.

Effect of microvascular pericytes of cochlear stria vascularis on endothelial cell permeability in C57BL/6J mice / 中华耳鼻咽喉头颈外科杂志

Objective: To study the changes in the permeability of the blood labyrinth barrier of the aging cochlea in mice, and to establish a non-contact co-culture model of endothelial cells (EC) and pericytes (PC) to furtherly investigate the cochlear stria vascularis microvascular pericytes impact on the permeability of endothelial cells. Methods: C57BL/6J mice were divided into two groups, three months old as young group, 12 months old as senile group. Cell experiment was divided into four groups, EC group, EC+PC co-culture group, D-gal+EC group and D-gal+EC+PC co-culture group. Auditory brainstem response (auditory brain response, ABR) was used to detect the auditory function of the two groups of mice. Evans blue staining was applied to detect the permeability of the cochlear blood labyrinth barrier of the two groups of mice. Transmission electron microscopy was used to observe the ultrastructure of blood labyrinth barrier endothelial cells, pericytes and tight junctions in the two groups of mice. Immunohistochemistry was used to detect the expression levels of tight junction proteins in the stria vascularis of the cochlea of the two groups of mice. Transwell chamber was used to detect the permeability of endothelial cells. Western blot and immunofluorescence technology were used to detect the expression level of tight junction protein on endothelial cells. SPSS 20.0 software was used to analyze the data. Results: Compared with the young group, the ABR threshold of the aging group was significantly increased, the latency of wave I was prolonged (t=10.25, P<0.01;t=5.61, P<0.05), the permeability of the cochlear blood labyrinth barrier was increased and the expression of tight junction protein on the vascular stria was decreased (P<0.05). The cochlear ultrastructure showed that the cochlear vascular stria microvascular lumen was deformed, the basement membrane thickened and the tight junction gap between endothelium enlarged. The positive rate of ECs and PCs in primary culture was more than 95%. The cells induced by 15 g/L D-gal were determined to be senescent cells. Compared with EC group, the expression of tight junction protein in endothelial cells of D-gal+EC group decreased（t=7.42，P<0.01；t=13.19，P<0.05）and the permeability increased (t=11.17, P<0.01). In the co-culture group, the expression of tight junction protein between endothelial cells in EC+PC co-culture group and D-gal+EC+PC co-culture group increased and the permeability decreased. Conclusions: In aging mice, the permeability of cochlear blood labyrinth barrier will increase and the level of tight junction protein will decrease; in aging state, cochlear vascular stria microvascular pericytes may affect endothelial cell permeability by regulating the expression of tight junction protein.

Effect of electrode array type and insertion technique on the insertion force: in vitro cochlear model study / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the effect of insertion technique and electrode array type on the insertion force of electrode array, and to provide a basis for further optimizing electrode design and facilitating mini-invasive electrode insertion. Methods: Three types of electrode array from Nurotron (Standard Electrode, Slim-medium Electrode, Slim-long Electrode) were studied. from July 2019 to December 2019. These electrode arrays were inserted into the phantom models of the cochlea, manually or robot-assisted(medium speed and low speed). The real-time force during electrode array insertion was recorded by ATI Nano 17 Ti sensors and was analyzed by accessory software. Origin 2020b software was used for statistical processing. Results: The insertion force of all electrode arrays progressively increased with the insertion depth. With the manual technique, the peak force of slim-medium electrode insertion was significantly smaller than that of the standard electrode insertion((71.0±16.6) mN vs (140.9±52.7) mN, Z=3.683, P<0.01), and the peak force of the slim-long electrode insertion was between the peak force of standard electrode and slim-medium electrode(P>0.05). No difference was found in the force variation of insertion among the three electrodes(P>0.05). With medium-speed and low-speed robotic assistance, the peak force characteristics of three electrodes were similar to those with the manual technique, but the force variation of standard electrode insertion ((83.9±9.7) mN/s) at medium speed was significantly larger than that of the slim-long electrode insertion ((69.2±4.0)mN/s), and the force variation of the standard electrode insertion at low speed was significantly greater than the other two electrodes. For the same electrode, robot-assisted insertion presented significantly lower peak force and force variation than manual insertion for each type of electrode array. But there was no difference in the peak force and force variation between two-speed levels of robot assistance (P>0.05). Conclusions: The insertion force of the electrode array will be lower when a slim electrode array or robot technique is applied. Long electrode array might make manual insertion difficult or less precise. Robot assistance has advantage on force control during electrode array insertion.

Use of scanning electron microscopy in the cochlea of guinea pigs / Microscopia eletrônica de varredura em cócleas de cobaias

Abstract Introduction: The use of electron microscopy in the study of the inner ear has allowed us to observe minute details of the hair cells, especially in ototoxicity studies; however, the preparation of this material is a difficult and delicate task. In an attempt to simplify the handling of these materials, two agents, toluidine blue and ethylenediamine tetra-acetic acid were tested, in addition to the elimination of osmium tetroxide during the preparation of albino guinea pig cochleae. We also tested the applicability of these methodologies in an ototoxicity protocol. Objective: To verify the quality of the images obtained with and without the use of ethylenediamine tetra-acetic acid, toluidine blue and osmium tetroxide in the preparation of cochleae of albino guinea pigs for the scanning electron microscopy. Methods: Three groups of cochleae were used. In Group 1, 10 cochleae were prepared with the usual methodology, dissecting the optical capsule without decalcification and using osmium tetroxide as a post-fixative agent. In Group 2, we prepared 10 cochleae decalcified with ethylenediamine tetra-acetic acid, injecting toluidine blue in the endolymphatic space to facilitate the identification of the organ of Corti. In Group 3, we used 4 cochleae of guinea pigs that received 3 doses of cisplatin (7.5 mg/kg, D1-D5-D6), two prepared according to the methodology used in Group 1 and two with that used in Group 2. Scanning electron microscopy images were obtained from the organ of Corti region of the basal turn of each cochlea. Results: The organ of Corti was more easily identified with the use of toluidine blue. The dissection of the cochlea was more accurate in the decalcified cochleae. The quality of the images and the preservation of the organ of Corti obtained with the two methodologies were similar. Conclusion: The proposed modifications resulted in images of similar quality as those observed using the traditional methodology.

Resumo Introdução: O emprego da microscopia eletrônica no estudo da orelha interna permitiu observar detalhes minuciosos das células ciliadas especialmente em estudos de ototoxicidade. Entretanto, o preparo desse material é trabalhoso e delicado. Para simplificar a manipulação desses materiais, testou-se o uso de dois agentes, azul de toluidina e ácido etilenodiamino tetra-acético, além da retirada do tetróxido de ósmio na preparação de cócleas de cobaias albinas. Testamos também a aplicabilidade dessas metodologias em um protocolo de ototoxicidade. Objetivo: Verificar a qualidade das imagens obtidas com e sem o uso de ácido etilenodiamino tetra-acético, azul de toluidina e tetróxido de ósmio na preparação de cócleas de cobaias albinas para a microscopia eletrônica de varredura. Método: Foram utilizados três grupos de cócleas. No Grupo 1 preparou-se 10 cócleas com a metodologia usual, dissecando a cápsula ótica sem descalcificac¸ão e utilizando tetróxido de ósmio como pós-fixador. No Grupo 2 preparamos 10 cócleas descalcificadas com ácido etilenodiamino tetra-acético, injetando azul de toluidina no espac¸o endolinfático para facilitar a identificação do órgão de Corti. No Grupo 3 utilizamos 4 cócleas de cobaias que receberam 3 doses de cisplatina (7,5 mg/kg, D1-D5-D6), duas preparadas com a metodologia do Grupo 1 e duas com a do Grupo 2. Foram obtidas imagens da microscopia eletrônica de varredura da região do órgão de Corti do giro basal de cada cóclea. Resultados: O órgão de Corti foi mais facilmente identificado com o azul de touidina. A dissecção da cóclea foi mais precisa nas cócleas descalcificadas A qualidade das imagens e a preservac¸ão do órgão de Corti obtidas com as duas metodologias foi similar. Conclusão: As modificações propostas resultaram em imagens de qualidade similar as observadas com o uso da metodologia tradicional.