Cochlear nerve deficiency（CND） is a rare inner ear malformation characterized by a hypoplastic or absent cochlear nerve, resulting in variable hearing loss or total deafness, depending on the quantity of nerve fibers present. About 18% of congenital hearing loss are associated with CND. It is a disease of uncertain cause. The outcome of auditory implant in CND patients varies widely. This article will discuss the related issues of CND.
Humans ; Cochlear Nerve/abnormalities* ; Cochlear Implants ; Child ; Cochlear Implantation/methods* ; Deafness ; Hearing Loss

Objective:To explore the value of high resolution computed tomography（HRCT） combined with Magnetic Resonance Imaging（MRI） in the diagnosis of inner ear malformation. Methods:HRCT and MRI data of 82 patients with inner ear malformations were analyzed retrospectively. HRCT MPR and CPR reconstruction of the inner ear structure, facial nerve canal and oblique sagittal MRI reconstruction of the internal auditory canal were performed. The inner ear malformations were classified, the conditions of facial nerve canal and cochlear nerve were evaluated. The association between inner ear malformation and cochlear nerve dysplasia were analyzed by Chi-square test with continuity correction. Results:Among the 82 patients with inner ear malformations,there were 49 cases of bilateral symmetry, 11 cases of bilateral asymmetry and 22 cases of unilateral inner ear malformations. Respectively, the most prevalent types were IP-Ⅱ（42.96%）, dilatation of atrium aqueduct（18.31%） and malformations of atrium and semicircular canal 19.72%. Out of 50 cases of cochlear malformations,only 3 were isolated cochlear malformations, and the rest were accompanied by other malformations of varying degrees. In the 67 ears examined by MRI, 26（38.81%） had cochlear nerve deficiency（CND）, and the incidence of CND varied with different types of inner ear malformations. Out of 142 ears, 28（19.72%） had abnormalities of the facial nerve canal. Conclusion:HRCT combined with MRI can accurately distinguish the types of inner ear malformation and effectively evaluate the facial nerve canal and cochlear nerve, and further provides the important finger and Guide value for the clinician to formulate the reasonable treatment and the operation plan.
Humans ; Ear, Inner/diagnostic imaging* ; Magnetic Resonance Imaging/methods* ; Retrospective Studies ; Female ; Male ; Tomography, X-Ray Computed/methods* ; Child ; Adolescent ; Adult ; Child, Preschool ; Cochlear Nerve/diagnostic imaging* ; Facial Nerve/abnormalities* ; Cochlea/abnormalities* ; Infant ; Young Adult

Objective:This study aims to investigate the mechanism and potential effects of two exposures to 100 dB sound pressure level（SPL） broadband white noise, with a 14-days interval, on the myelin sheath of the cochlear auditory nerve in mice. The research provides experimental evidence for understanding the pathophysiological processes of noise-induced hearing loss and hidden hearing loss. Methods:Fifteen 6-week-old male C57BL/6J mice with normal hearing thresholds were randomly divided into three groups: a control group（no noise exposure）, a single noise exposure group, and a double noise exposure group. The single noise exposure group was exposed to 100 dB SPL white noise for 2 hours, and ABR thresholds were measured 1 day（P1） and 14 days（P14） after the exposure. The double noise exposure group was exposed to the same conditions of 100 dB SPL white noise for 2 hours, followed by a second identical exposure 14 days later. ABR thresholds were measured 1 day（P15） and 14 days（P28） after the second exposure. The cochleae of all three groups were then collected for immunofluorescence observation of the basilar membrane and transmission electron microscopy to observe changes in the structure of the auditory nerve myelin sheath. Results:In the single noise exposure group, ABR thresholds at all frequencies were significantly elevated compared to the control group at P1. There were no significant changes in ABR thresholds at any frequency at P14. In the double noise exposure group, ABR thresholds at all frequencies were significantly elevated compared to the control group at P15 and P28（P<0.001）. After the first noise exposure, immunofluorescence observation revealed no significant weakening of the auditory nerve myelin sheath signal; transmission electron microscopy showed no significant changes in myelin sheath morphology. However, after the second noise exposure, immunofluorescence observation revealed a weakening of the myelin sheath signal, and transmission electron microscopy showed thinning of the myelin sheath, disruption of the lamellar structure, and separation from the axon, indicating demyelination. Conclusion:Two exposures to 100 dB SPL broadband white noise can lead to damage to the auditory nerve myelin sheath in mice, whereas a single exposure does not cause significant changes.
Animals ; Male ; Myelin Sheath/pathology* ; Mice ; Cochlear Nerve/pathology* ; Mice, Inbred C57BL ; Noise/adverse effects* ; Hearing Loss, Noise-Induced/physiopathology* ; Cochlea ; Evoked Potentials, Auditory, Brain Stem

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.
Female ; Male ; Humans ; Middle Aged ; Neuroma, Acoustic/surgery* ; Action Potentials ; Evoked Potentials, Auditory, Brain Stem ; Cochlea ; Cochlear Nerve

Objective: To explore the value of electrically evoked auditory brainstem response (EABR) monitoring combined with brainstem auditory evoked potential (BAEP) and compound action potential (CAP) monitoring during vestibular schwannoma resection for the protection of the cochlear nerve. Methods: Clinical data from 12 patients with vestibular schwannomas who had useful hearing prior to surgery were analyzed at the PLA General Hospital from January to December 2021. Among them, there were 7 males and 5 females, ranging in age from 25 to 59 years. Before surgery, patients underwent audiology assessments (including pure tone audiometry, speech recognition rate, etc.), facial nerve function evaluation, and cranial MRI. They then underwent vestibular schwannoma resection via the retrosigmoid approach. EABR, BAEP, and CAP were simultaneously monitored during surgery, and patients' hearing preservation was observed and analyzed after surgery. Results: Prior to surgery, the average PTA threshold of the 12 patients ranged from11 to 49 dBHL, with a SDS of 80% to 100%. Six patients had grade A hearing, and six patients had grade B hearing. All 12 patients had House-Brackman grade I facial nerve function prior to surgery. The MRI indicated tumor diameters between 1.1 and 2.4 cm. Complete removal was achieved in 10/12 patients, while near-total removal was achieved in 2/12 patients. There were no serious complications at the one-month follow-up after surgery. At the three-month follow-up, all 12 patients had House-Brackman grade I or II facial nerve function. Under EABR with CAP and BAEP monitoring, successful preservation of the cochlear nerve was achieved in six of ten patients (2 with grade B hearing, 3 with grade C hearing, and 1 with grade D hearing). Successful preservation of the cochlear nerve was not achieved in another four patients (all with grade D hearing). In two patients, EABR monitoring was unsuccessful due to interference signals; however, Grade C or higher hearing was successfully preserved under BAEP and CAP monitoring. Conclusion: The application of EABR monitoring combined with BAEP and CAP monitoring during vestibular schwannoma resection can help improve postoperative preservation of the cochlear nerve and hearing.
Male ; Female ; Humans ; Adult ; Middle Aged ; Neuroma, Acoustic/complications* ; Hearing/physiology* ; Evoked Potentials, Auditory, Brain Stem/physiology* ; Cochlear Nerve ; Hearing Loss, Sensorineural/etiology* ; Retrospective Studies ; Postoperative Complications/prevention & control*

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.
Child, Preschool ; Female ; Humans ; Infant ; Male ; Cochlea ; Cochlear Implantation/methods* ; Cochlear Implants ; Cochlear Nerve ; Electric Stimulation ; Evoked Potentials, Auditory/physiology*

Mice ; Animals ; Spiral Ganglion/physiology* ; Cochlea/physiology* ; Neurons

PURPOSE: Auditory nerve injury is one of the most common nerve injury complications of skull base fractures. However, there is currently a lack of auxiliary examination methods for its direct diagnosis. The purpose of this study was to find a more efficient and accurate means of diagnosis for auditory nerve injury. METHODS: Through retrospectively analyzing the results of brainstem auditory evoked potential (BAEP) and high-resolution CT (HRCT) in 37 patients with hearing impairment following trauma from January 1, 2018 to July 31, 2020, the role of the two inspection methods in the diagnosis of auditory nerve injury was studied. Inclusion criteria were patient had a clear history of trauma and unilateral hearing impairment after trauma; while exclusion criteria were: (1) severe patient with a Glasgow coma scale score ≤5 because these patients were classified as severe head injury and admitted to the intensive care unit, (2) patient in the subacute stage admitted 72 h after trauma, and (3) patient with prior hearing impairment before trauma. According to Goodman's classification of hearing impairment, the patients were divided into low/medium/severe injury groups. In addition, patients were divided into HRCT-positive and negative groups for further investigation with their BAEP results. The positive rates of BEAP for each group were observed, and the results were analyzed by Chi-square test (p < 0.05, regarded as statistical difference). RESULTS: A total of 37 patients were included, including 21 males and 16 females. All of them were hospitalized patients with GCS score of 6-15 at the time of admission. The BAEP positive rate in the medium and severe injury group was 100%, which was significantly higher than that in the low injury group (27.27%) (p < 0.01). The rate of BEAP positivity was significantly higher in the HRCT-positive group (20/30, 66.7%) than in the HRCT-negative group (1/7, 14.3%) (p < 0.05). Twenty patients (54.05%) were both positive for BEAP and HRCT test, and considered to have auditory nerve damage. Six patients (16.22%) were both negative for BEAP and HRCT test, and 10 patients (27.03%) were BAEP-negative but HRCT-positive: all the 16 patients were considered as non-neurological injury. The rest 1 case (2.70%) was BAEP-positive but HRCT-negative, which we speculate may have auditory nerve concussion. CONCLUSION By way of BAEP combining with skull base HRCT, we may improve the accuracy of the diagnosis of auditory nerve injury. Such a diagnostic strategy may be beneficial to guiding treatment plans and evaluating prognosis.
Cochlear Nerve ; Evoked Potentials, Auditory, Brain Stem/physiology* ; Female ; Hearing Loss ; Humans ; Male ; Retrospective Studies ; Skull Base/diagnostic imaging* ; Tomography, X-Ray Computed

Objective: To analyze the temporal bone CT and inner ear magnetic resonance imaging characteristics of cochlear implant patients with no cochlear nerve display in the inner auditory canal under MRI. To retrospectively analyze the long-term hearing and speech rehabilitation effects of such patients after cochlear implant. And to analyze the correlation between the results of imaging examinations and the postoperative effects of cochlear implant patients with this type of cochlear nerve deficiency. Methods: A total of 88 children with cochlear nerve deficiency, who underwent cochlear implantation in Shandong Provincial ENT Hospital from May 2014 to October 2018, were enrolled. Patients with cochlear malformations were excluded,only the patients with cochlear nerve deficiency whose cochlear structure was normal and no cochlear nerve displayed in inner auditory canal under MRI were enrolled. There were 64 patients, including 4 bilaterally implanted, 68 ears in total, with an average age of (2.8±1.7) years (range 1-6 years) at the time of implantation. The implanted product was Cochlear, including 24RECA and 512 models. All patients underwent inner ear magnetic resonance imaging and temporal bone CT scan before operation. Auditory speech function assessments were performed at 12 months, 24 months, and 36 months after surgery, including categories of auditory performance (CAP), speech intelligibility rating (SIR) and hearing aid threshold test. The imaging evaluation content included the width of the cochlear nerve canal of temporal bone CT, the width of the internal auditory canal, the width of the auditory nerve at the cerebellopontine angle of the inner ear MRI, and the ratio of the facial nerve to the width of the auditory nerve at the cerebellopontine angle. The correlations between the results of postoperative hearing aid hearing threshold, CAP, SIR and imaging results were analyzed. Results: Among the 64 cases of cochlear nerve not shown under MRI, 56 ears with CT data showed that the width of the cochlear nerve canal in temporal bone CT was (0.72±0.30) mm (mean±standard deviation, the same below), and the width of the internal auditory canal was (4.07±1.10) mm; 66 ears with MRI data showed that the diameter of the auditory nerve at the cerebellopontine angle of the inner ear MRI was (1.58±0.27) mm, the diameter of the facial nerve was (1.57±0.27) mm, and the ratio of the diameter of the facial nerve to the auditory nerve was (1.02±0.23). The average hearing thresholds at 12, 24, and 36 months after surgery were (46.8±2.5) dB HL, (40.7±0.8) dB HL, and (36.8±1.5) dB HL, respectively. The preoperative and postoperative CAP scores at 12, 24 and 36 months were (1.0±1.0), (3.8±1.4), (4.5±1.4) and (5.1±0.7) points, respectively. The preoperative and postoperative SIR scores at 12, 24, and 36 months were (1.1±0.3), (1.9±0.9), (2.5±0.9), and (2.9±0.6) points, respectively. The hearing threshold at 24 months after surgery was negatively correlated with the width of the internal auditory canal of temporal bone CT (r=-0.349, P=0.037), and the hearing threshold at 36 months after surgery was positively correlated with the ratio of the diameter of the facial nerve to the auditory nerve at the cerebellopontine angle of the inner ear MRI (r=0.740, P=0.001). Conclusions: Children with cochlear implants whose cochlear nerves are not shown on MRI can benefit from cochlear implantation, and their speech and auditory functions can improve significantly after surgery. The width of the internal auditory canal in the temporal bone CT and the ratio of the diameter of the facial nerve to the auditory nerve at the cerebellopontine angle of the inner ear MRI may be related to the long-term hearing threshold after surgery.
Child ; Child, Preschool ; Cochlear Implantation ; Cochlear Implants ; Cochlear Nerve/diagnostic imaging* ; Hearing Loss, Sensorineural/surgery* ; Humans ; Infant ; Magnetic Resonance Imaging ; Prognosis ; Retrospective Studies ; Speech Intelligibility

Animals ; Apoptosis ; Cochlea ; Estrogens/pharmacology* ; Mice ; Mice, Inbred C57BL ; Neurons ; Spiral Ganglion