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Introduction Cochlear implantation is an effective treatment method for severe to profound hearing loss. Many factors that may influence cochlear implantation success have been explained in previous studies. Apart from those, minor differences in size of normal cochlear nerves may affect postoperative performance. Objective To investigate whether the minor differences in cochlear nerve size in normal cochlear nerves affect postoperative cochlear implant performance. Methods 30 pediatric prelingually deaf patients who were treated with cochlear implantation were included in this study. From the reconstructed parasagittal magnetic resonance images, the diameter and cross-sectional area of the cochlear nerve on the ipsilateral and contralateral side were measured. Auditory evaluations were performed 1, 3, 6 and 12 months following the first fitting. All the analysis was performed by using EARS®, evaluation of auditory responses to speech tool. Correlation between cochlear nerve diameter, cross-sectional area and postoperative auditory perception was analyzed to determine whether variation in cochlear nerve size contributes to postoperative auditory performance. Results The mean diameter of the cochlear nerve on the ipsilateral side was 718.4 μm (504.5 − 904.3 μm) and mean cross sectional area was 0.015 cm2 (0.012 − 0.018 cm2). On the contralateral side the mean cochlear nerve diameter was 714.4 μm (502.6 − 951.4 μm) and mean cross sectional area was 0.014 cm2 (0.011 − 0.019 cm2). The correlation between the diameter and cross-sectional area of the ipsilateral and contralateral cochlear nerve revealed no significance. Mean score at first month monosyllable-trochee-polysyllable test, MTP1, was 0.17 (0.08 − 0.33), at 6th month with 6 words test, 6th month MTP6 was 0.72 (0.39 − 1.0), at 6th month with 12 words, 6th month MTP 12 was 0.46 (0.17 − 0.75) and at 12th month with 12 words, 12th month MTP12 was 0.73 (0.25 − 1.0). There was no correlation between the monosyllable-trochee-polysyllable test, values at any time with the diameter of the ipsilateral cochlear nerve. However, the first month MTP, 6th month MTP6 and 12th month MTP12 correlated with the cross-sectional area of the ipsilateral cochlear nerve. Conclusion Measuring the cross sectional area of the normal- appearing cochlear nerve may give important prognostic knowledge on cochlear implant outcomes. In patients with a larger cross sectional area the auditory performance was better and faster. Although normal appearing, slight differences on cross sectional area of the cochlear nerve may affect performance. Measuring the size of the cochlear nerve on parasagittal magnetic resonance images may provide beneficial information on the postoperative rehabilitation process. Resumo Introdução O implante coclear é um método de tratamento eficaz para a perda auditiva grave a profunda. Muitos fatores que podem influenciar o sucesso do implante coclear foram explicados em estudos anteriores. Além desses fatores, pequenas diferenças no tamanho dos nervos cocleares normais podem afetar o desempenho pós-operatório. Objetivo Investigar se pequenas diferenças no tamanho dos nervos cocleares normais afetam o desempenho pós-operatório do implante coclear. Método Foram incluídos neste estudo 30 pacientes pediátricos surdos pré-linguais, tratados com implante coclear. A partir de imagens de ressonância magnética parassagitais reconstruídas, foram medidos o diâmetro e a área de seção transversal do nervo coclear no lado ipsilateral e contralateral. As avaliações auditivas foram feitas 1, 3, 6 e 12 meses após a primeira adaptação. Todas as análises foram feitas com a ferramenta EARS® (do inglês evaluation of auditory responses to speech). A correlação entre o diâmetro do nervo coclear, a área transversal e a percepção auditiva pós-operatória foi analisada para determinar se a variação no tamanho do nervo coclear contribui para o desempenho auditivo pós-operatório. Resultados O diâmetro médio do nervo coclear no lado ipsilateral foi de 718,4 μm (504,5 a 904,3 μm) e a área da seção transversal média foi de 0,015 cm2 (0,012-0,018 cm2). No lado contralateral, o diâmetro médio do nervo coclear foi de 714,4 μm (502,6 a 951,4 μm) e a área da seção transversal média foi de 0,014 cm2 (0,011 a 0,019 cm2). A correlação entre o diâmetro e a área transversal do nervo coclear ipsilateral e contralateral não revelou qualquer significância. O escore médio do teste monosyllable-trochee-polysyllable no primeiro mês, denominado MTP1, foi de 0,17 (0,08-0,33), no sexto mês com teste de 6 palavras, MTP6, foi de 0,72 (0,39-1,0), no sexto mês com 12 palavras, MTP12, foi de 0,46 (0,17-0,75) e no 12° mês com 12 palavras, MTP12, foi de 0,73 (0,25-1,0). Não houve correlação entre os valores do teste monosyllable-trochee-polysyllable em qualquer momento com o diâmetro do nervo coclear ipsilateral. Entretanto, o teste monosyllable-trochee-polysyllable do primeiro mês, do 6° mês, e o do 12° mês correlacionaram-se com a área transversal do nervo coclear ipsilateral. Conclusão Medir a área da secção transversal do nervo coclear de aparência normal pode fornecer conhecimento prognóstico importante sobre os resultados do implante coclear. Em pacientes com área da secção transversal maior, o desempenho auditivo foi melhor e mais rápido. Embora o nervo coclear pareça normal, pequenas diferenças na área da secção transversal do nervo coclear podem afetar o desempenho, de forma que a medida do tamanho do nervo coclear nas imagens de ressonância magnética na projeção parassagital pode fornecer informações benéficas sobre o processo de reabilitação pós-operatória.

Objective Axenfeld-Rieger syndrome (ARS) type 3 is a rare autosomal dominant disease, characterized by anterior segment dysgenesis of the eye, hearing loss, and cardiac defects. ARS type 3 is highly associated with FOXC1 mutations, which induces developmental disorders of neural crest cells. Most studies about ARS patients focused on ophthalmologic findings, but details in their hearing loss have not yet been revealed. In this report, we investigated audiological and otological manifestations in the ARS type 3 patient who had the novel heterozygous FOXC1 mutation leading deletion at the forkhead DNA-binding domain. Methods and Results Pure tone audiometry showed bilateral sensorineural hearing loss (SNHL) and audiological examinations confirmed that major dysfunctions existed in the cochlea, rather than the spiral ganglion neurons and the cochlear nerve. CT and MRI revealed the hypoplastic cochlea at both sides. Given that the 6p25 deletion syndrome, lacking one allele of the FOXC1 gene, shows similar, but more severe cochlear malformations than the present case, the FOXC1 mutations might contribute to the hypoplasia and dysfunctions in the cochlea. Conclusion To our knowledge, this is the first report demonstrating that the ARS type 3 patient with the FOXC1 mutation has the hypoplasia and dysfunctions in the cochlea, which results in bilateral SNHL.

ZusammenfassungAusgewertet wurden 86 Patienten mit einem retrosigmoidal mikrochirurgisch resezierten Vestibularisschwannom im Tumorstadium Koos II–IV. Es zeigte sich, dass im Bereich des inneren Gehörgangs in über 2/3 der Fälle der Nervus cochlearis dem elektroneurographisch leicht zu identifizierenden Nervus facialis in immer wiederkehrenden ähnlichen Verlaufsmustern folgte. Ausgehend vom Fundus erleichterte dies die frühzeitige Identifizierung und damit den Kontinuitätserhalt des Nervus cochlearis im Verlauf des inneren Gehörgangs. Dies war vor allem dann von Bedeutung, wenn ein sicherer Funktionserhalt aufgrund der Tumorgröße oder -formation trotz intraoperativer Ableitung somatosensorischer Potenziale nicht sicher gewährleistet werden konnte, aber die Möglichkeit einer späteren Hörrehabilitation mit einem Cochleaimplantat bestehen bleiben sollte. Präoperative Magnetresonanztomographie(MRT)-Sequenzen ergaben zwar in einigen Fällen einen Hinweis auf die möglichen Nervenverläufe, die intraoperative Darstellung im inneren Gehörgang war der MRT aber überlegen.

Introduction Cryptococcus spp. is a fungus responsible for 600,000 deaths per year worldwide, mainly in immunosuppressed subjects. However, 20% of cases occur in immunocompetent subjects. Neuropathic disorders involving the auditory nerve have been reported, but vestibular disorders have never been described in detail. We report the case of an immunocompetent man, who presented audiovestibular disorders leading to a diagnosis of cryptococcal meningitis. Case report A 39-year-old man was referred for balance disorders and right sensorineural hearing loss. He presented right vestibulo-saccular impairment and bilateral absence of auditory brainstem responses. Brain MRI was suggestive of cryptococcal meningitis. A cystic lesion in the right flocculus compressed the vestibulocochlear nerve. During monthly follow-up, pure tone audiometry gradually improved and speech audiometry in silence returned to normal. Partial resynchronization of the auditory afferent pathways was observed only on the contralateral side to vestibulocochlear nerve compression, while complete recovery of saccular function was observed. Discussion Cryptococcal meningitis in immunocompetent subjects may be accompanied by lesions of the auditory and vestibular afferent pathways. Recovery of hearing and balance was observed in response to medical treatment and early vestibular rehabilitation.

Objectives Histologic reports of temporal bones of ears with vestibular schwannomas (VSs) have indicated findings of endolymphatic hydrops (ELH) in some cases. The main goal of this investigation was to test ears with VSs to determine if they exhibit electrophysiological characteristics similar to those of ears expected to experience ELH. Design Fifty-three subjects with surgically confirmed VS aged ≥18 and with normal middle ear status were included in this study. In addition, a second group of adult subjects (n = 24) undergoing labyrinthectomy (n = 6) or endolymphatic sac decompression and shunt (ELS) placement (n = 18) for poorly controlled vestibular symptoms associated with Meniere's disease (MD) participated in this research. Intraoperative electrocochleography (ECochG) from the round window was performed using tone burst stimuli. Audiometric testing and word recognition scores (WRS) were performed preoperatively. ECochG amplitudes, cochlear microphonic/auditory nerve neurophonic (ANN) in the form of the "ongoing" response and summation potential, were analyzed and compared between the two groups of subjects. In addition, to evaluate any effect of auditory nerve function, the auditory nerve score was calculated for each subject. Pure-tone averages were obtained using the average air conduction thresholds at 0.5, 1, and 2 kHz while WRS was assessed using Northwestern University Auditory Test No. 6 word lists. Results In the VS group the average pure-tone averages and WRS were 59.6 dB HL and 44.8%, respectively, while in the MD group they were 52.3 dB HL and 73.8%. ECochG findings in both groups revealed a reduced trend in amplitude of the ongoing response with increased stimulus frequency. The summation potential amplitudes of subjects with VS were found to be less negative than the MD subjects for nearly all test frequencies. Finally, the VS group exhibited poorer amounts of auditory nerve function compared to the MD group. Conclusions The current findings suggest cochlear pathology (e.g., hair cell loss) in both groups but do not support the hypothesis that VSs cause ELH.

Background and objective Vestibular schwannoma is a benign tumour that originates in the eighth cranial nerve. It is termed intralabyrinthine schwannoma (ILS) when it develops in the inner ear, this being a rare origin. We present our experience in the management of three patients with ILS. Materials and methods The results of tumour excision and cochlear implantation were evaluated in three patients with ILS: two intracochlear schwannomas (ICS) and one intravestibular schwannoma (IVS). Results Prior to surgery, all patients presented progressive sensorineural hearing loss and tinnitus. Complete tumour resection and cochlear implantation was possible in all patients, with favourable hearing rehabilitation. Conclusions The therapeutic approach will depend on tumour size, growth rate, degree of hearing loss and presence of vestibular symptoms. Cochlear implantation (CI) in patients with ILS is possible when the cochlear nerve is present and functional. CI in patients, whether or not preceded by tumour excision, is an option with good hearing results in selected patients.

Background High-resolution MR imaging enables the visualization of individual nerves in the internal auditory canal (IAC). Cochlear nerve deficiency (CND) is recognized as one of the major causes of sensory neural hearing loss (SNHL), especially in cases of unilateral hearing loss in childhood. Some patients with CND are thought to have accompanying vestibular nerve deficiency (VND). However, there have been few reports focusing on VND and vestibular function in these children. Aims The aim of this study was to evaluate the frequency of VND and vestibular dysfunction in children with unilateral SNHL caused by CND. Material and methods Thirty-eight children with unilateral SNHL, who were diagnosed with CND by 3 T-MRI, were evaluated for VND and underwent caloric testing and cervical vestibular evoked potential (cVEMP). Results Fourteen of 38 patients (37%) had VND, and eleven (29%) of the patients [ten of the patients (71%) with VND] had at least one vestibular dysfunction. The patients with VND had significantly worse hearing and an IAC of smaller diameter than did patients without VND. Conclusions and significance We should pay attention to VND as well as vestibular dysfunction in hearing loss patients with CND.

OBJECTIVE To study the auditory outcome of simultaneous translabyrinthine vestibular schwannoma (VS) resection and cochlear implantation (CI) after successful cochlear nerve preservation. STUDY DESIGN A retrospective case series and patient questionnaire. SETTING Quaternary referral center for skull base pathologies. PATIENTS Patients with small (

Objective To compare conventional method and compressed‐sensing (CS) accelerated 3D balanced fast field echo imaging (bFFE) of inner ear. Methods Twenty patients with suspected inner ear disease underwent CS accelerated 3D‐bFFE (CS‐bFFE) and conventional 3D‐bFFE (Con‐bFFE) by a 3T MRI. The overall image quality, motion artifacts, and image quality of specific structures of inner ear were assessed on ordinal scales by three radiologists who were blinded to the scan protocols. Kendall W test was used to evaluate interobserver agreement and Wilcoxon test was performed to compare the image quality and motion artifacts between CS‐bFFE and Con‐bFFE. Results The acquisition duration of CS‐bFFE (1 min 53 s) was 49% faster than Con‐bFFE. Three radiologists had good inter‐observer agreement of image quality (Kendall W value of 0.829 for CS‐bFFE and 0.815 for Con‐bFFE) and motion artifacts evaluation (Kendall W value of 0861 for CS‐bFFE and 0.707 for Con‐bFFE). The better overall image quality of CS‐bFFE was assessed (4.93 ± 0.23 for CS‐bFFE, 4.53 ± 0.70 for Con‐bFFE, Z = −2.254, p = 0.024). The image quality score of facial and cochlear nerve gained higher in CS‐bFFE (4.93 ± 0.23 for CS‐bFFE, 4.58 ± 0.64 for Con‐bFFE, Z = −2.094, p = 0.036). No significant difference of motion artifacts (p = 0.050) between CS‐bFFE and Con‐bFFE. Conclusions The CS‐bFFE improves image quality and reduces acquisition time significantly, and it is a feasible MRI protocol for inner ear imaging.

Neural stimulation with infrared radiation has been explored for brain tissue, peripheral nerves, and cranial nerves including the auditory nerve. Initial experiments were conducted at wavelengths between λ = 1850 and λ = 2140 nm and the radiant energy was delivered with square pulses. Water absorption of the infrared radiation at λ = 1860 nm is similar to absorption at wavelengths between λ = 1310 and λ = 1600 nm, which are in the radiation wavelength range used for the communication industry. Technology for those wavelengths has already been developed and miniaturized and is readily available. The possibility of the infrared light to evoke compound action potentials (CAP) in the cochlea at λ = 1,375, λ = 1,460, and λ = 1550 nm was explored and compared to that of λ = 1860 nm in guinea pigs. Furthermore, rise and fall times of the 100 μs long pulses were changed and four basic pulse shapes (square, triangular, ramp-up, and ramp-down) were explored in their ability to evoke a CAP. In animals with pure tone threshold averages (PTAs) above 70 dB SPL, the results show that the favorable wavelength is λ = 1460 nm to reach threshold for stimulation and λ = 1375 nm or λ = 1460 nm for obtaining maximum amplitude. The most favorable pulse shape is either ramp-up or triangular.

The traditional method of recording electrically evoked compound action potentials (ECAPs), as implemented in the MAESTRO clinical software (standard ART), requires manual adjustments during threshold determination through a specialist. The "FineGrain" research tool (FineGrain RT) uses a continuous stimulation paradigm combined with automatic ECAP threshold determination. The aim of this study was to compare the FineGrain RT with standard ART.ECAPs were recorded with standard ART and the FineGrain RT in paediatric cochlear implant recipients. Different stimulation rates were used for FineGrain ECAP recordings (40, 60, and 76 Hz).Thirteen children (6 - 19 years) participated in this study - nine were bilaterally and four unilaterally implanted, resulting in a total of twenty-two implanted ears.ECAP threshold determination success rates were similar between the two approaches (92% and 89%) and ECAP thresholds correlated well (r: 0.94,TheFineGrain research approach is a reliable replacement for standard ART in clinical practice.

Human hearing loss is often accompanied by comorbidities like tinnitus. This perception of phantom sounds without external stimulation is affecting up to 15% of the adult population and can lead to psychological disorders like depression. Animal studies in rodents could show that tinnitus may not only be a result of hearing loss due to cochlear hair cell damage but can also be a consequence of synaptopathy at the inner hair cells already induced by moderate sound traumata (hidden hearing loss). In this study we investigate the synaptopathy previously shown in mice in our animal model, the Mongolian gerbil, and relate it to behavioral signs of tinnitus in this species. Tinnitus was induced by a mild monaural acoustic trauma leading to a monaural noise induced hearing loss in the animals quantified by auditory brainstem response audiometry. Behavioral signs of tinnitus percepts were detected by measurement of pre-pulse inhibition of the acoustic startle response in a gap-noise paradigm in about two-thirds of the animals. 14 days after trauma the cochleae of traumatized and non-traumatized ears were isolated and inner hair cell synapses were counted within several spectral regions of the cochlea. In the here presented preliminary data inner hair cell synaptopathy was only found in animals with behavioral signs of tinnitus, independent of type of hearing loss. On the other hand, animals with apparent hearing loss but without behavioral signs of tinnitus showed a reduction in amplitudes of auditory brainstem response waves I/II (cochlear nerve and dorsal cochlear nucleus) but no significant changes in the number of synapses at the inner hair cells. We conclude – in line with the literature – that hearing loss is caused by damage to the inner and / or outer hair cells but that the development of tinnitus, at least in our animal model is closely linked to synaptopathy at the inner hair cells.

Sporadic vestibular schwannomas (VS) can be treated using radiation therapy, microsurgical resection or a wait‐and‐scan approach. In general, small VS are usually followed (wait‐and‐scan) until a significant amount of growth per year is seen. In a recent study, 212 cases of VS were observed over time; 66% showed growth, of which 30% were fast growing (doubling in size in a year). 1 Frischer et al examined cases of VS after radiosurgery (Gamma Knife), and found a tumour control rate of 92% after 5 years of follow‐up. 2 However, among patients with initial Gardner‐Robertson class 1 or 2 hearing, only 55% maintained serviceable hearing (class 1 or 2) after 2 years, and 34% after 10 years. Several other studies have reported similar results. 3 , 4 A recent meta‐analysis concluded that among patients who undergo microsurgical treatment with a hearing‐preserving technique, 35–49% still have serviceable hearing five years later. 5 The above‐mentioned findings support the conclusion that most VS will require treatment after some period of observation. However, the currently available treatment options carry a high risk of loss of serviceable hearing. Some authors believe that the possibility of cochlear implantation in the setting of VS should completely change the treatment strategy for this disease. 6 However, patient outcomes with cochlear implants (CI) show a wide variation—with some patients having no auditory perception, while others exhibit open‐set speech understanding. 7 The intraoperative testing of cochlear nerve function using electrically evoked brainstem response audiometry (eABR) provides a means of objectively assessing cochlear nerve conduction, and has been increasingly applied in this setting. 7 , 8 In the present study, we aimed to assess outcomes of patients undergoing VS resection and CI, and to develop a new scoring system to preoperatively identify suitable patients for this treatment course. Appropriate preoperative classification of patients can have important impacts on patient counseling and expectations.

Cochlear implants are considered the gold standard therapy for subjects with severe hearing loss and deafness. Cochlear implants bypass the damaged hair cells and directly stimulate spiral ganglion neurons (SGNs) of the auditory nerve. Hence, the presence of functional SGNs is crucial for speech perception in electric hearing with a cochlear implant. In deaf individuals, SGNs progressively degenerate due to the lack of neurotrophic support, normally provided by sensory cells of the inner ear. Adipose-derived stromal cells (ASCs) are known to produce neurotrophic factors. In a guinea pig model of sensory hearing loss and cochlear implantation, ASCs were autologously transplanted into the scala tympani prior to insertion of a cochlear implant on one side. Electrically evoked auditory brain stem responses (eABR) were recorded 8 weeks after cochlear implantation. At conclusion of the experiment, the cochleae were histologically evaluated. Compared to untreated control animals, transplantation of ASCs resulted in an increased number of SGNs and their peripheral neurites. In ASC-transplanted animals, mean eABR thresholds were lower and suprathreshold amplitudes larger, suggesting a larger population of intact auditory nerve fibers. Moreover, when compared to controls, amplitude-level functions of eABRs in ASC transplanted animals demonstrated steeper slopes in response to increasing interphase gaps (IPGs), indicative of better functionality of the auditory nerve. In summary, results suggest that transplantation of autologous ASCs into the deaf inner ear may have protective effects on the survival of SGNs and their peripheral processes and may thus contribute to long-term benefits in speech discrimination performance in cochlear implant subjects.

Összefoglaló. Bevezetés: A cochlearis implantátum egy műtétileg behelyezett elektromos eszköz, amely az akusztikus hanghullámokat elektromos jelekké alakítja, közvetlenül a hallóideget stimulálja, így segíti a súlyos fokú hallássérüléssel vagy teljes hallásvesztéssel élők életét. Cochlearis implantációt követően a legjobb rehabilitációs eredmény elérésének technikai feltétele többek között az esetre szabott elektródaválasztás és az elektródasor teljes, kontrollált, szövődménymentes bejuttatása a scala tympaniba, miközben a cochlea belső struktúrája a lehető legkisebb mértékben sérül. A rutin intraoperatív elektrofiziológiai tesztek fontos információt adnak a készülék működőképességéről és a hallóideg stimulációjáról, azonban nem hagyatkozhatunk rájuk az elektródasor cochleán belüli helyzetének igazolásában. Mivel előfordulhat, hogy a rendelkezésre álló elektrofiziológiai vizsgálatok eredménye megfelelő, és mégis rendellenes helyzetbe kerül az elektróda, az arany standardot a képalkotó vizsgálatok jelentik. Módszer: Közleményünkben egy modern, hibrid műtő által nyújtott technológiai háttér új alkalmazási területét mutatjuk be. Szimultán kétoldali cochlearis implantációt végeztünk Cochlear Nucleus Slim Modiolar típusú perimodiolaris elektródasorral, a belső fül fejlődési rendellenességével rendelkező betegen. Az intraoperatív képalkotást Siemens Artis pheno C-karos robot digitális szubtrakciós angiográfiás rendszer biztosította valós idejű átvilágító és volumentomográfiás funkcióval. Eredmények: Az intraoperatív képalkotás által dinamikusan követhető az elektródasor bevezetésének folyamata, ellenőrizhető az elektródasor statikus helyzete, így kiváltható a rutinnak számító posztoperatív képalkotó vizsgálat. A rendellenes helyzetbe kerülő elektródasor pozíciója egy ülésben korrigálható, az újból bevezethető, így elkerülhető az újabb altatással járó, bizonytalan kimenetelű revíziós műtét. Következtetés: A hibrid műtő jól kontrollált, minimálisan invazív eljárások elvégzését biztosítja. Különösen a hallószerv fejlődési rendellenessége vagy egyéb, az elektródának a cochleába vezetését nehezítő rendellenesség esetén javasolt a műtői képalkotó diagnosztika. Orv Hetil. 2021; 162(22): 878–883. Summary. Introduction: The cochlear implant is a surgically inserted electrical device that converts acoustic sound waves into electrical signals to stimulate the cochlear nerve, thus helps the rehabilitation of people with severe to total hearing loss. One of the most important technical conditions for achieving the best rehabilitation result after cochlear implantation is the personalized choice of electrodes. Additionally, it is vital that there is a complete, controlled, uncomplicated delivery of the electrode array to the scala tympani while minimizing damage to the inner structures of the cochlea. Routine electrophysiological tests provide important information about device functionality and auditory nerve stimulation. However, they probably do not show an abnormal position of the electrode array within the cochlea. Thus, imaging studies remain the gold standard. Method: In our paper, we present a novel application field of the modern technological background provided by a hybrid operating room. Simultaneous bilateral cochlear implantation was performed with cochlear implants with perimodiolar electrode array (Nucleus Slim Modiolar) in a patient with cochlear malformation. Intraoperative imaging was provided by a Siemens Artis pheno C-arm robot digital subtraction angiography system with real-time fluoroscopy and volume tomography function. Results: Intraoperative imaging ensures dynamic follow-up of the introduction and static determination of the position of the electrode array and replaces routine postoperative imaging. If the electrode array was inserted in an abnormal position, the revision can be performed in the same sitting. Also, the revision surgery with a potential risk of uncertain outcome, alongside additional anaesthesia, can be prevented. Conclusion: The hybrid operating room ensures that well-controlled, minimally invasive procedures are performed. Intraoperative imaging can be imperative in malformed cochleae and conditions that may complicate electrode insertion. Orv Hetil. 2021; 162(22): 878–883.

Introduction:To investigate the relationship between morphometric variants of the cochlear nerve (CN) and the hearing level. To investigate the confounding effects of age, sex, and audiometric variables on the relationship between CN morphometrics and hearing loss, if present.Methods:Audiological data and magnetic resonance imaging findings of 127 patients with asymmetrical sensorineural hearing loss (ASNHL) were reviewed retrospectively. According to pure tone average (PTA) frequencies of each ear, difference above 25 dB were accepted as ASNHL. The vertical (Vd) and horizontal diameters (Hd) and the cross-sectional area (CSA) of the CN were measured.Results:The difference in CSA and Vd between ears showed a negative correlation with age. The mean CSA was 1.57 in AE and 1.60 in NE. Mean Hd was 1.00 in AE and 1.00 NE. Mean Vd was 1.40 in AE and 1.50 in NE. There was no correlation between the difference ratios of thresholds and CN diameter parameters. There was no significant correlation of CSA, Vd, and Hd with PTA thresholds at each frequency.Conclusion:Aging is associated with losses in Vd diameter and CSA. The degree of hearing loss was not correlated with the morphometric features of the CN. The morphometry of the CN should be interpreted together with the etiology of hearing loss.

Cochlear nerve deficiency is one of the known causes of congenital sensorineural hearing loss. Management of hearing loss in children with cochlear nerve deficiency poses a multidimensional challenge. The absent or hypoplastic cochlear nerve may prevent electrical stimulation from reaching the brainstem and the auditory cortex. A deficient cochlear nerve can be associated with other inner ear malformations, which may diminish the success of cochlear implantation in those children. Promising results in adults after auditory brainstem implantation led to the expansion of candidacy to include the pediatric populations who were contraindicated for CIs. To review the outcomes of cochlear implantation versus that of auditory brainstem implantation in children with various conditions of the auditory nerve. This retrospective chart review study comprised two pediatric groups. The first group consisted of seven ABI recipients with cochlear nerve aplasia and the second group consisted of another seven children with cochlear nerve deficiencies who underwent CI surgery. The participants’ auditory skills and speech outcomes were assessed using different tests selected from the Evaluation of Auditory Responses to Speech (EARS) test battery. There were some individual variations in outcomes depending on the status of the auditory nerve. The mean CAP score of the ABI group was 2.87, while the mean SIR score was 0.62. On the other hand, the mean CAP score of the CI group was 1.29, while the mean SIR score was 0.42. Our results are in good agreement with the reported auditory perception and speech and language development outcomes of pediatric auditory brainstem implantation. We added to the growing body of literature on the importance of verifying and identifying the status of the cochlear nerve in the decision-making process of the surgical management of those pediatric groups.

Electrocochleography (ECochG) is an electrophysiological technique that records electrical potentials generated by different components of the inner ear and peripheral cochlear nerve in response to acoustic stimulation. ECochG responses can be analyzed into (1) cochlear microphonics (CM), (2) auditory nerve neurophonics, (3) summating potential, and (4) compound action potential. Over the past few decades, there have been ongoing refinements in technique and updates in the understanding of recorded potentials. Historically, ECochG found its main application in the diagnostic evaluation of Meniere’s disease (MD). However, in the last decade, the focus has shifted towards cochlear implantation (CI). In patients with residual hearing after CI, combined electric and acoustic stimulation has resulted in improved hearing and speech outcomes. Despite efforts to mitigate trauma during electrode insertion, hearing preservation rates vary after surgery. During implantation, real-time ECochG offers an opportunity to measure frequency specific CMs elicited from a localized region in the cochlea as the surgeon inserts the electrode array. In extracochlear ECochG recordings, the recording electrode can be placed on the promontory, the stapes, or the tympanic membrane. Intracochlear ECochG can be performed by inserting a recording electrode into the cochlea or by using one of the CI electrodes as the recording electrode. The loss of intraoperative ECochG signal may indicate cochlear trauma from electrode insertion, but the association between intraoperative ECochG changes and cochlear trauma remains controversial. The ability to monitor cochlear trauma during CI electrode placement holds promise to improve hearing preservation outcomes, modify surgical techniques, and change electrode design. The goal of this review is to provide a comprehensive overview of the electrophysiology and history of ECochG, discuss its recent applications in CI, and explore the ongoing research in this expanding field.

FEASIBILITY AND EFFECTIVENESS OF RETROSIGMOID APPROACH IN VESTIBULAR SCHWANNOMA SURGERYPurpose: To assess the feasibility and effectiveness of the lateral suboccipital retrosigmoid approach in the surgical management of vestibular schwannoma.Materials and Methods: We conducted a prospective hospital-based case series conducted on 356 patients during the period from May 2018 to May 2020 in collaboration with the neurosurgery department, "Sohag University hospital", and "Tokyo Medical University Hospital". Patients included who were undergoing surgical intervention for vestibular schwannoma (VS) through retrosigmoid approach. All patients in our study were followed up for a minimum of four months. For each patient intraoperative tumor resection volume was recorded, postoperative complications, facial and cochlear nerve functions were assessed.Results: Enrolled in this study 356 cases, the majority (54.8%) of patients were females; while (45.2%) were males were included with a mean age (42.57 ± 12.3) years. We achieved a mean follow-up of 6.2 months; ranging (4-9 months). Postoperative scoring of facial nerve function was a good outcome in 79.4%, fair outcome in 17.5%, and poor outcome in 3.1%.Conclusion: We assessed the results of surgery using a retrosigmoid approach in 356 patients with VS. Surgical management of VS using retrosigmoid approach is safe and effective but after the advancement of microsurgical techniques like drilling and neurophysiological monitoring especially for seventh and eighth cranial nerves, the possibility of preserving the facial and cochlear functions became more feasible with excellent results.

Permanent threshold elevation after noise exposure or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of the synapses between sensory cells and auditory nerve fibers. Silencing these neurons is likely to degrade auditory processing and may contribute to difficulties understanding speech in noisy backgrounds. Reduction of suprathreshold ABR amplitudes can be used to quantify synaptopathy in inbred mice. However, ABR amplitudes are highly variable in humans, and thus more challenging to use. Since noise-induced neuropathy preferentially targets fibers with high thresholds and low spontaneous rate and because phase locking to temporal envelopes is particularly strong in these fibers, measuring envelope following responses (EFRs) might be a more robust measure of cochlear synaptopathy. A recent auditory model further suggests that modulation of carrier tones with rectangular envelopes should be less sensitive to cochlear amplifier dysfunction and, therefore, a better metric of cochlear neural damage than sinusoidal amplitude modulation. In this study, we measure performance scores on a variety of difficult word-recognition tasks among listeners with normal audiograms and assess correlations with EFR magnitudes to rectangular versus sinusoidal modulation. Higher harmonics of EFR magnitudes evoked by a rectangular-envelope stimulus were significantly correlated with word scores, whereas those evoked by sinusoidally modulated tones did not. These results support previous reports that individual differences in synaptopathy may be a source of speech recognition variability despite the presence of normal thresholds at standard audiometric frequencies. NEW & NOTEWORTHY Recent studies suggest that millions of people may be at risk of permanent impairment from cochlear synaptopathy, the age-related and noise-induced degeneration of neural connections in the inner ear. This study examines electrophysiological responses to stimuli designed to improve detection of neural damage in subjects with normal hearing sensitivity. The resultant correlations with word recognition performance are consistent with a contribution of cochlear neural damage to deficits in hearing in noise abilities.

The auditory brainstem implant (ABI) was originally developed to provide rehabilitation of retrocochlear deafness caused by neurofibromatosis type 2 (NF2). Recent studies of the ABI have investigated outcomes in non-NF2 cohorts, such as patients with cochlear nerve aplasia or cochlear ossification and more recently, intractable tinnitus. New technologies that improve the ABI-neural tissue interface are being explored as means to improve performance and decrease side effects. Innovative discoveries in optogenetics and bioengineering present opportunities to continually evolve this technology into the future, enhancing spatial selectivity of neuronal activation in the cochlear nucleus and preventing side effects through reduction in activation of non-target neuronal circuitry. These advances will improve surgical planning and ultimately improve patients’ audiological capabilities. ABI research has rapidly increased in the 21st century and applications of this technology are likely to continually evolve. Herein, we aim to characterize ongoing clinical, basic science, and bioengineering advances in ABIs and discuss future directions of this technology.

Vestibular schwannomas (VS) are benign tumors that originate from the nerve sheath of one of the two vestibular nerves. VS can have a severe impact on everyday life of the patient and may lead to symptoms such as vertigo, hearing loss (e.g., as sudden deafness), deafness, and tinnitus. Treatment concepts include observational waiting with regular imaging control (“wait and scan”), radiotherapy, or surgical resection. Depending on the size of the tumor and status of functional hearing, the surgical approach may be retrosigmoidal, transtemporal, retrolabyrinthine, or translabyrinthine. The translabyrinthine approach always results in complete deafness due to opening of the bony labyrinth. If the nerve structure of the cochlear nerve is preserved, hearing rehabilitation with a cochlear implant (CI) may be successful. In this article the surgical technique for microsurgical resection of VS using a translabyrinthine approach with simultaneous cochlear implantation under intraoperative monitoring of the cochlear nerve by electrical stimulation is presented.

To investigate changes in DTI (Diffusion Tensor Imaging) parameters in brainstem subcortical auditory pathways after Gamma Knife Radiosurgery (GKR) in patients with intracanalicular vestibular schwannoma (ICVS) and to analyze the relationship between tumor volume and ADC (apparent diffusion coefficient) and FA (fractional anisotropy) values.Seventeen patients with ICVS were evaluated before and after GKR. ADC and FA values of the lateral lemniscus (LL) and inferior colliculus (IC) and tumor volume were calculated. Patients who responded to GKR were classified as Group 1 and those who did not respond adequately as Group 2. The relationship between ADC and FA values and changes in tumor volume were analyzed.Tumor volume significantly decreased after GKR. ADC values obtained from the tumor increased after GKR (p:0.002). There was no significant difference in LL and IC before and after GKR in terms of FA and ADC values (n:17). There was a positive correlation between response to treatment and contralateral LL ADC values after GKR (p=0.005, r:0.652). There was a negative correlation between contralateral IC FA values after GKR and response to treatment (p=0.017, r: -0.568). There was a significant difference between Groups 1 and 2 in regards to contralateral LL ADC (p=0.03) and IC FA values (p=0.017).Since the cochlear nerve and subcortical auditory pathways have low regeneration potential after nerve damage, ADC and FA changes in LL and IC may be explained with the presence of intracanalicular tumors prior to GKR. Since GKR does not cause additional damage to the subcortical auditory pathways at the brainstem level, we think that GKR is a noninvasive treatment method that can be used safely in patients with ICVS.İntrakanaliküler vestibüler schwannomlu (ICVS) olgularda Gamma Knife Radyocerrahisi (GKR) sonrası beyin sapı subkortikal işitsel yollarda DTG (Difüzyon Tensör Görüntüleme) parametrelerinde değişiklik olup olmadığını araştırmak ve tümör hacmi ile ADC (görünür difüzyon katsayısı) ve FA (görünür difüzyon katsayısı) değerleri arasındaki ilişkiyi analiz etmek.ICVS’li 17 hasta radyocerrahi öncesi ve sonrası değerlendirildi. Lateral lemniscus (LL) ve inferior kollikulus (IC) ADC ve FA değerleri ve tümör hacmi hesaplandı. Radyocerrahi tedavisine yanıt verenler Grup 1, yeterli yanıt vermeyenler ise Grup 2 olarak sınıflandırıldı. ADC ve FA değerleri ile tümor hacim değişiklikleri arasındaki ilişki analiz edildi.Radyocerrahi sonrası tümör hacmi belirgin azalmıştı. GKR sonrası tümörden elde edilen ADC de-ğerleri arttı (p:0,002). GKR öncesi ve sonrası LL ve IC’de FA ve ADC değerleri (n:17) açısından anlamlı farklılık saptanmadı. Tedaviye yanıt ile GKR sonrası kontralateral LL ADC değerleri arasında pozitif korelasyon mevcuttu (p=0,005, r:0,652). GKR sonrası kontralateral IC FA değerleri ile tedaviye yanıt arasında negatif korelasyon saptandı (p=0,017, r:-0,568). Grup 1 ile Grup 2 arasında kontralateral LL ADC (p=0,03) ve IC FA değerleri (p=0,017) açısından anlamlı fark vardı.Kohlear sinir ve subkortikal işitme yolakların düşük rejenerasyon potansiyeli sahip olması nedeniyle LL ve IC’deki ADC ve FA değişiklikleri mevcut olan intrakanaliküler tümör varlığı ile açıklanabilir. Radyocerrahi, beyin sapı düzeyinde subkortikal işitme yollarına ek hasar vermediğinden dolayı GKR’nin ICVS’li hastalarda güvenle kullanılabilecek noninvaziv bir tedavi yöntemi olduğunu düşünüyoruz.

OBJECTIVE To analyze the changes of cochlear nerve diameter and the presence of a cochlear nerve deficit at a high-frequency region and investigate their effects on cochlear implant (CI) performance in postlingual deaf adults. STUDY DESIGN Retrospective. SETTING Tertiary care academic center. PATIENTS Eighty-three postlingual deaf adults with no labyrinthine anomalies or cognitive deficits who received a CI with perimodiolar electrodes from a single manufacturer. MAIN OUTCOMES AND MEASURES We evaluated the changes of cochlear nerve diameter and the presence of a "tail sign," defined as identifiable nerve fibers originating from the far basal turn of the cochlea, which represents the presence of cochlear nerve at a high-frequency region in magnetic resonance imaging, on monosyllabic word recognition scores. RESULTS The cochlear nerve diameter showed a positive correlation with word recognition scores (maximum diameter, R2 = 0.26, p

Objectives Describe the effect of preoperative sudden hearing loss (SHL) on likelihood of hearing preservation (HP) after surgical resection of vestibular schwannoma (VS). Study design Retrospective chart review. Setting Tertiary referral center. Patients Adult patients (≥18 years) who underwent retrosigmoid VS resection for HP between February 2008 and December 2018 were reviewed. All patients had preoperative word recognition score (WRS) of at least 50%. Similarly, HP was defined as postoperative WRS of more than or equal to 50%. Regression analysis was used to describe the effect of SHL on HP, accounting for tumor size, and preoperative hearing quality. Interventions All patients underwent retrosigmoid VS resection for HP. Main outcome measures WRS of at least 50%. Results Of 160 patients who underwent retrosigmoid VS resection during the study period, 153 met inclusion criteria. Mean tumor size was 14.0 (±6) mm. Hearing was preserved in 41.8% (n = 64). Forty patients (26.1%) had a history of preoperative SHL. Among 138 patients (90.2%) in whom the cochlear nerve was anatomically preserved during surgery, HP was achieved in 61.8% of those with SHL (21 of 34) and 41.3% of those without SHL (43 of 104) (p = 0.0480). On univariate and multivariate analysis (accounting for tumor size and preoperative hearing quality), SHL was a significant positive predictor of HP (odds ratio 2.292, p = 0.0407 and odds ratio 2.778, p = 0.0032, respectively). Conclusion In patients with VS and retained serviceable hearing, SHL is an independent predictor of HP after retrosigmoid microsurgical resection when the cochlear nerve is preserved.

Smith–Lemli–Opitz syndrome (SLOS) is an autosomal recessive multiple congenital malformation and intellectual disability syndrome resulting from variants in DHCR7. Auditory characteristics of persons with SLOS have been described in limited case reports but have not been systematically evaluated. The objective of this study is to describe the auditory phenotype in SLOS. Age- and ability-appropriate hearing evaluations were conducted on 32 patients with SLOS. A subset of 21 had auditory brainstem response testing, from which an auditory neural phenotype is described. Peripheral or retrocochlear auditory dysfunction was observed in at least one ear of 65.6% (21) of the patients in our SLOS cohort. The audiometric phenotype was heterogeneous and included conductive, mixed, and sensorineural hearing loss. The most common presentation was a slight to mild conductive hearing loss, although profound sensorineural hearing loss was also observed. Abnormal auditory brainstem responses indicative of retrocochlear dysfunction were identified in 21.9% of the patients. Many were difficult to test behaviorally and required objective assessment methods to estimate hearing sensitivity. Individuals with SLOS are likely to have hearing loss that may impact communication, including speech and language development. Routine audiologic surveillance should be conducted to ensure prompt management of hearing loss.

Management of small vestibular schwannomas (VSs) remains controversial. When surgery is chosen, the preservation of facial and cochlear nerve function is a priority. In this report, we introduce and evaluate a technique to anatomically preserve the vestibular nerves to minimize manipulation and preserve the function of the facial and cochlear nerves. The vestibular nerve preservation technique was prospectively applied to resect small VS tumors in patients with serviceable preoperative hearing (American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B). Clinical and radiological data were recorded and analyzed. Ten patients met the inclusion criteria. The mean (SD) age was 40.4 (12.5) years. Follow-up ranged from 6 weeks to 2 years. The maximum tumor diameter parallel to the internal auditory canal ranged from 10 to 20 mm (mean, 14.9 (3.1) mm). There were three Koos grade 3 and seven Koos grade 2 tumors. Gross total resection was achieved in all cases. Both the facial and cochlear nerves were anatomically preserved in all cases. Postoperatively, 7 patients (70%) remained in the AAO-HNS class A or B hearing category. None of the patients had new vestibular symptoms, and all had House–Brackmann grade 1 facial function. Nervus intermedius dysfunction was observed in 1 patient preoperatively, which worsened postoperatively. Two patients had new nervus intermedius symptoms postoperatively. Improvement of facial nerve and hearing outcomes is feasible through the intentional preservation of the vestibular nerves in the resection of small VSs. Longer follow-up is required to rule out tumor recurrence.

Hearing is one of our most important means of communication. Disabling hearing loss (DHL) is a long-standing, unmet problem in medicine, and in many elderly people, it leads to social isolation, depression, and even dementia. Traditionally, major efforts to cure DHL have focused on hair cells (HCs). However, the auditory nerve is also important because it transmits electrical signals generated by HCs to the brainstem. Its function is critical for the success of cochlear implants as well as for future therapies for HC regeneration. Over the past two decades, cell transplantation has emerged as a promising therapeutic option for restoring lost auditory nerve function, and two independent studies on animal models show that cell transplantation can lead to functional recovery. In this article, we consider the approaches most likely to achieve success in the clinic. We conclude that the structure and biochemical integrity of the auditory nerve is critical and that it is important to preserve the remaining neural scaffold, and in particular the glial scar, for the functional integration of donor cells. To exploit the natural, autologous cell scaffold and to minimize the deleterious effects of surgery, donor cells can be placed relatively easily on the surface of the nerve endoscopically. In this context, the selection of donor cells is a critical issue. Nevertheless, there is now a very realistic possibility for clinical application of cell transplantation for several different types of hearing loss.

Cochlear implantation (CI) is a safe and beneficial surgery for children with congenital inner ear malformations, with the exception of cochlear nerve aplasia. The combination of microtia with middle and inner ear abnormalities is extremely uncommon and sufficiently severe to make a surgical approach to the cochlea difficult. We report herein the case of a 2-year-old girl who presented with profound bilateral sensorineural hearing loss, congenital aural atresia, microtia, and inner ear malformations. High-resolution computed tomography revealed poor development of the bilateral middle ear spaces, absence of the incus and stapes, aberrant courses of facial nerves, aplastic lateral semicircular canals, and covered round windows. With intraoperative imaging assistance, sequential bilateral CI was performed using a transmastoid approach with no complication. We propose that CI is feasible in patients with severe external and middle ear malformations. However, major malformations increase the risk of complications. As the facial nerve and cochlea are difficult to locate due to the lack of important anatomical landmarks, detailed planning and adequate preparation, including review of the preoperative imaging data, and the use of facial nerve monitoring and intraoperative imaging are very important. In addition, experienced surgeons should perform CI to ensure the success of the operation.

Background An electrical potential not previously reported—electrical cochlear response (ECR)—observed only in implanted patients is described. Its amplitude and growth slope are a measurement of the stimulation achieved by a tone pip on the auditory nerve. The stimulation and recording system constructed for this purpose, the features of this potential obtained in a group of 43 children, and its possible clinical use are described. The ECR is obtained by averaging the EEG epochs acquired each time the cochlear implant (CI) processes a tone pip of known frequency and intensity when the patient is sleeping and using the CI in everyday mode. The ECR is sensitive to tone pip intensity level, microphone sensitivity, sound processor gain, dynamic range of electrical current, and responsiveness to electrical current of the auditory nerve portion involved with the electrode under test. It allows individual evaluation of intracochlear electrodes by choosing, one at the time, the central frequency of the electrode as the test tone pip frequency, so the ECR measurement due to a variable intensity tone pip allows to establish the suitability of the dynamic range of the electrode current. Results There is a difference in ECR measurements when patients are grouped based on their auditory behavior. The ECR slope and amplitude for the Sensitive group is 0.2 μV/dBHL and 10 μV at 50 dBHL compared with 0.04 μV/dBHL and 3 μV at 50dBHL for the Inconsistent group. The clinical cases show that adjusting the dynamic range of current based on the ECR improved the patient’s auditory behavior. Conclusions ECR can be recorded regardless of the artifact due to the electromyographic activity of the patient and the functioning of the CI. Its amplitude and growth slope versus the intensity of the stimulus differs between electrodes. The relationship between minimum ECR detection intensity level and auditory threshold suggests the possibility of estimating patient auditory thresholds this way. ECR does not depend on the subject’s age, cooperation, or health status. It can be obtained at any time after implant surgery and the test procedure is the same regardless of device manufacturer.

Introduction Good hearing in pilots, including central auditory skills, is critical for flight safety and the prevention of aircraft accidents. Pure tone audiometry alone may not be enough to assess hearing in the members of this population who, in addition to high noise levels, routinely face speech recognition tasks in non-ideal conditions.Objective To characterize the frequency-following response (FFR) of a group of military pilots compared with a control group.Methods Twenty military pilots in the Study Group and 20 non-pilot military personnel, not exposed to noise in their work, in the Control Group, all with normal hearing, aged between 30 and 40 years old, completed a questionnaire to assess their hearing habits, and their FFRs were measured with a /da/ syllable (duration 40 milliseconds, speed 10.9/s), at 80 dB NA in the right ear. All procedures were approved by the ethical committee of the institution. Statistical analysis was performed using the t-Student or Mann-Whitney tests for quantitative variables, and the Fisher or chi-squared tests for qualitative variables, and a value of p Results There was no significant difference between the groups regarding auditory habits. In the FFR, wave amplitudes A (p = 0.01) and C (p = 0.04) were significantly lower in the Study Group.Conclusion Working as a military pilot can be a crucial factor in determining an individual's typical FFR pattern, demonstrated in the present study by statistically significant reductions in the amplitudes of the A and C waves.

OBJECTIVE Objective measurements may assist in indicating cochlear implants and in predicting outcomes of cochlear implantation surgery. Using electrically evoked compound action potentials (ECAP), information about the function of the auditory nerve can be obtained by analyzing responses to electrical stimulation transmitted and derived by the recording electrode. The aim of this study was to determine whether ECAP characteristics differ depending on the stimulated intracochlear region and the size of the cochlea. STUDY DESIGN Retrospective cohort study. SETTING University Medical center, tertiary academic referral center. PATIENTS Patients undergoing cochlear implant surgery between 2015 and 2018. INTERVENTION Cochlear implantation with FLEXsoft electrode arrays (length 31.5 mm, 12 stimulating channels). MAIN OUTCOME MEASURES The cochlear duct length (CDL) and the cochlear coverage (CC) were measured using a new computed tomography-based software and correlated to the postoperative speech performance. Additionally, ECAP were measured and associated to the CDL. RESULTS A total of 59 ears of 53 cochlear implant users with a mean age of 63.6 (SD 14.9) years were included. The mean estimated CDL was 35.0 (SD 2.2) mm. The mean CC was 90.3% (SD 5.5%). A total of 4,873 ECAP were measured. A statistically significant, moderate, negative correlation between the ECAP slope and the site of stimulation was found (r = -0.29, 95% confidence interval: -0.32 to -0.27, p

Animal models of noise-induced hearing loss (NIHL) show a dramatic mismatch between cochlear characteristic frequency (CF, based on place of innervation) and the dominant response frequency in single auditory-nerve-fiber responses to broadband sounds (i.e., distorted tonotopy, DT). This noise trauma effect is associated with decreased frequency-tuning-curve (FTC) tip-to-tail ratio, which results from decreased tip sensitivity and enhanced tail sensitivity. Notably, DT is more severe for noise trauma than for metabolic (e.g., age-related) losses of comparable degree, suggesting that individual differences in DT may contribute to speech intelligibility differences in patients with similar audiograms. Although DT has implications for many neural-coding theories for real-world sounds, it has primarily been explored in single-neuron studies that are not viable with humans. Thus, there are no noninvasive measures to detect DT. Here, frequency following responses (FFRs) to a conversational speech sentence were recorded in anesthetized male chinchillas with either normal hearing or NIHL. Tonotopic sources of FFR envelope and temporal fine structure (TFS) were evaluated in normal-hearing chinchillas. Results suggest that FFR envelope primarily reflects activity from high-frequency neurons, whereas FFR-TFS receives broad tonotopic contributions. Representation of low- and high-frequency speech power in FFRs was also assessed. FFRs in hearing-impaired animals were dominated by low-frequency stimulus power, consistent with oversensitivity of high-frequency neurons to low-frequency power. These results suggest that DT can be diagnosed noninvasively. A normalized DT metric computed from speech FFRs provides a potential diagnostic tool to test for DT in humans. A sensitive noninvasive DT metric could be used to evaluate perceptual consequences of DT and to optimize hearing-aid amplification strategies to improve tonotopic coding for hearing-impaired listeners.

Loss of auditory-nerve (AN) afferent cochlear innervation is a prevalent human condition that does not affect audiometric thresholds and therefore remains largely undetectable with standard clinical tests. AN loss is widely expected to cause hearing difficulties in noise, known as “hidden hearing loss,” but support for this hypothesis is controversial. Here, we used operant conditioning procedures to examine the perceptual impact of AN loss on behavioral tone-in-noise (TIN) sensitivity in the budgerigar (Melopsittacus undulatus; of either sex), an avian animal model with complex hearing abilities similar to humans. Bilateral kainic acid (KA) infusions depressed compound AN responses by 40–70% without impacting otoacoustic emissions or behavioral tone sensitivity in quiet. Surprisingly, animals with AN damage showed normal thresholds for tone detection in noise (0.1 ± 1.0 dB compared to control animals; mean difference ± SE), even under a challenging roving-level condition with random stimulus variation across trials. Furthermore, decision-variable correlations (DVCs) showed no difference for AN-damaged animals in their use of energy and envelope cues to perform the task. These results show that AN damage has less impact on TIN detection than generally expected, even under a difficult roving-level condition known to impact TIN detection in individuals with sensorineural hearing loss (SNHL). Perceptual deficits could emerge for different perceptual tasks or with greater AN loss but are potentially minor compared with those caused by SNHL.SIGNIFICANCE STATEMENTLoss of auditory-nerve (AN) cochlear innervation is a common problem in humans that does not affect audiometric thresholds on a clinical hearing test. AN loss is widely expected to cause hearing problems in noise, known as “hidden hearing loss,” but existing studies are controversial. Here, using an avian animal model with complex hearing abilities similar to humans, we examined for the first time the impact of an experimentally induced AN lesion on behavioral tone sensitivity in noise. Surprisingly, AN-lesioned animals showed no difference in hearing performance in noise or detection strategy compared with controls. These results show that perceptual deficits from AN damage are smaller than generally expected, and potentially minor compared with those caused by sensorineural hearing loss (SNHL).

Objective Loss of spiral ganglion neurons (SGN) is permanent and responsible for a substantial number of patients suffering from hearing impairment. It can derive from the degeneration of SGNs due to the death of sensory hair cells as well as from auditory neuropathy. Utilizing stem cells to recover lost SGNs increasingly emerges as a possible therapeutic option, but access to human SGNs is difficult due to their protected location within the bony impacted cochlea. Aim of this study was to establish a reliable and practicable approach to access SGNs in the human temporal bone for possible stem cell and gene therapies. Methods In seven human temporal bone specimen a transcanal approach was used to carefully drill a cochleostomy in the lateral second turn followed by insertion of a tungsten needle into the apical modiolus to indicate the spot for intramodiolar injections. Subsequent cone beam computed tomography (CBCT) served as evaluation for positioning of the marker and cochleostomy size. Results The apical modiolus could be exposed in all cases by a cochleostomy (1.6 mm2, standard deviation ±0.23 mm2) in the lateral second turn. 3D reconstructions and analysis of CBCT revealed reliable positioning of the marker in the apical modiolus, deviating on average 0.9 mm (standard deviation ±0.49 mm) from the targeted center of the second cochlear turn. Conclusion We established a reliable, minimally invasive, transcanal surgical approach to the apical cochlear modiolus in the human temporal bone in foresight to stem cell-based and gene therapy of the auditory nerve.

Objective Hearing loss is a highly penetrant phenotype in NLRP3 (Nod-Like-Receptor-Pyrin containing 3) gene-related autoinflammatory disorders. A recent study revealed potential medical treatment of hearing loss with anakinra (anti-interleukin 1 receptor antagonist) in selected cases. However, for severely aggravated hearing loss not responsive to anakinra, cochlear implantation (CI) would be the last resort for hearing rehabilitation. Outcome of CI is not clearly elucidated yet in this emerging type of hearing loss related to NLRP3-related autoinflammatory disorders, which has a systemic nature and ubiquitous distribution of resident macrophages involving the spiral ganglion neuron and the cochlear nerve. Here, we report the successful outcome of CI in NLRP3-related autoinflammatory disorder. Patients Three subjects representing each type of NLRP3-related autoinflammatory disorder: chronic infantile, neurological, cutaneous, and articular syndrome; Muckle-Wells syndrome; and DFNA34, who underwent CI for auditory rehabilitation, were recruited. Interventions Phenotypes as well as genotypes were reviewed in the subjects. Main outcome measures Audiologic performances before/after CI over time were evaluated. Results All three subjects showed excellent audiological outcomes with rapid improvement of speech perception test result reaching plateau at 3 months after CI, although distribution of the disease predicted poor outcome based on theoretical analysis. Conclusions This is the first report to present outcome of CI among subjects with a confirmed NLRP3 genetic etiology and resultant systemic inflammation, and suggests that CI is a viable treatment option in this disease entity.

Clinical application of electrically-evoked intracochlear auditory brainstem responses (eABRs) for evaluation of brainstem maturity or aging changes has not been well investigated.We compare the eV latencies of intraoperative eABR measurements in one-year-olds, infants, children, adults, and the elderly, with the goal of investigating the changes in the brainstem auditory pathway due to development and aging.We studied 58 ears of 51 patients who underwent cochlear implantation between 2013 and 2019 using MED-EL's Concerto or Synchrony implants with Flex28 or Flex soft electrodes. EABRs were recorded during cochlear implantation. The stimuli were delivered by the MED-EL Maestro to the apical, middle, and basal turn electrodes at stimulus levels 1000, 800, and 600 cu, with a pulse width of 30 µs.In eABRs recorded from electrodes installed at both the mastoid and nape, there was no difference in latency between age groups within each stimulus level.ABR latency was not affected by development after age one and aging of the brainstem auditory pathway. Our study will be useful as a control in identifying abnormal eABR wave configurations in patients with cochlear malformations, cochlear nerve deficiencies, or auditory neuropathy, regardless of age.

Congenital aural atresia (CAA) is usually accompanied by an anomalous course of facial nerves, which may run over the round window niche toward the promontory in some cases of CAA. Very rarely, cochlear malformation might coexist at the same ear which has CAA, in which case cochlear implantation can be difficult due to anomalous facial nerve. Herein we present a case of cochlear implantation performed in a child who had CAA along with cochlear hypoplasia and cochlear nerve aplasia. The mastoid segment of facial nerve was displaced anteriorly, running over the round window niche. The surgery was done successfully using the round window approach without facial nerve injury.

Background: The spread of excitation (SOE) and auditory nerve recovery function (REC) are objective measures recorded by neural response telemetry and may interfere in cochlear implant (CI) stimulation. Objective: To analyze and correlate SOE with the refractory periods in subjects with pre- and postlingual deafness implanted with different electrode arrays. Methods: This was a retrospective study of 323 ears separated by perimodiolar or straight arrays and by pre- or postlingually deaf recipients. Measures were collected intraoperatively on electrode 11. The SOE width was measured in millimeters at the 0.75 point of the curve, and the relative (tau) and absolute (t0) refractory periods were measured in microseconds. Results: There was a statistical correlation between the SOE and the t0 in the patients with postlingual deafness implanted with the perimodiolar array. The SOE width was statistically different between the straight and perimodiolar arrays and between the pre- and postlingual groups in the perimodiolar array. Tau was statistically different between the pre- and postlingual groups with the straight array and the t0, between the pre- and postlingual groups with the perimodiolar array. Neural response threshold and amplitude of the neural response were not statistically different among groups. Conclusion: There was a correlation between SOE width and t0 only in patients with acquired deafness. The findings suggest that different factors influence SOE and REC, considering SOE is different according to the electrode array and REC being different according the onset of deafness.

Objective Cochlear implantation in children with inner ear malformations has been shown to be beneficial. The aims of this study are to evaluate open set word recognition outcomes among children with cochlear implants who have cochlear malformations, and to further assess if either the lateral wall (LW) or perimodiolar (PM) electrode arrays confer any performance outcome advantages. Study design Retrospective case series. Setting Tertiary referral center. Patients Pediatric cochlear implant recipients with cochlear malformations who were implanted at our institution within the last 10 years and had speech perception scores were eligible for inclusion in the study. Potential participants were excluded if they had less than 1 year of listening experience with the cochlear implant or suspected cochlear nerve deficiency. Intervention None. Main outcome measure Most recent consonant-nucleus-consonant word score. Results ANOVA analysis demonstrated that the type of cochlear malformation was significantly associated with speech perception outcome (p = 0.006). Those with IP2 malformations had significantly better word recognition outcomes than the remaining cochlear malformations. Array type (LW or PM) was not associated with better word recognition outcomes in long-term follow-up of patients with IP2 malformations (p = 0.13). Conclusions In children who have cochlear malformations, cochlear implantation results in varying word recognition outcomes based on the type of malformation. While the participants in this study demonstrated postoperative open set word recognition skills, those with IP2 malformations demonstrated the most benefit. Electrode type was not found to significantly impact outcomes in this cohort.

The indications for cochlear implantation have gradually expanded as advancements in technology have evolved, resulting in improved audiologic outcomes for both adult and children. There remains a significant underutilization of cochlear implant technology in the United States, and recognition of the potential benefits of cochlear implantation for non-traditional indications is critical for encouraging the evolution of candidacy criteria. Adult cochlear implantation candidacy has progressed from patients with bilateral profound sensorineural hearing loss (SNHL) to include patients with greater degrees of residual hearing, single-sided deafness and asymmetric hearing, and atypical etiologies of hearing loss (eg, vestibular schwannoma, Ménière’s disease, and otosclerosis). Indications for pediatric cochlear implantation have similarly evolved from children with bilateral severe to profound SNHL to implanting children at a younger age, including those with residual hearing, asymmetric hearing loss, inner ear malformations, as well as cochlear nerve deficiency. In this editorial, the literature investigating cochlear implantation for nontraditional indications is reviewed with an aim to use the best available evidence to encourage the evolution of candidacy criteria.

Hearing loss caused by noise exposure, ototoxic drugs, or aging results from the loss of sensory cells, as reflected in audiometric threshold elevation. Animal studies show that loss of hair cells can be preceded by loss of auditory-nerve peripheral synapses, which likely degrades auditory processing. While this condition, known as cochlear synaptopathy, can be diagnosed in mice by a reduction of suprathreshold cochlear neural responses, its diagnosis in humans remains challenging. To look for evidence of cochlear nerve damage in normal hearing subjects, we measured their word recognition performance in difficult listening environments and compared it to cochlear function as assessed by otoacoustic emissions and click-evoked electrocochleography. Several electrocochleographic markers were correlated with word scores, whereas distortion product otoacoustic emissions were not. Specifically, the summating potential (SP) was larger and the cochlear nerve action potential (AP) was smaller in those with the worst word scores. Adding a forward masker or increasing stimulus rate reduced SP in the worst performers, suggesting that this potential includes postsynaptic components as well as hair cell receptor potentials. Results suggests that some of the variance in word scores among listeners with normal audiometric threshold arises from cochlear neural damage. NEW & NOTEWORTHY Recent animal studies suggest that millions of people may be at risk of permanent impairment from cochlear synaptopathy, the age-related and noise-induced degeneration of neural connections in the inner ear that “hides” behind a normal audiogram. This study examines electrophysiological responses to clicks in a large cohort of subjects with normal hearing sensitivity. The resultant correlations with word recognition performance are consistent with an important contribution cochlear neural damage to deficits in hearing in noise abilities.

Objective This study reports two potential biomarkers of the physiological status of the cochlear nerve (CN) in cochlear implant users. Design This project represents a complementary analysis on a subset of electrophysiological data from our recently published study. This study compared changes in N1 latency and stimulation level (i.e., N1 latency offset and stimulation level offset) with increasing interphase gap of a biphasic pulse between children with cochlear nerve deficiency and children with normal-sized CNs. Results Children with cochlear nerve deficiency showed smaller N1 latency offsets and larger stimulation level offsets than children with normal-sized CNs at all electrode locations tested. Conclusions The N1 latency and stimulation level offsets differ in two patient populations with different physiological statuses of the CN. These parameters may be useful for evaluating CN function in individual cochlear implant patients.

This review highlights our current understanding of the impact of unilateral hearing loss and single-sided deafness in children, offering insight into diagnosis and management. Children with unilateral hearing loss develop an aural preference toward their better hearing ear, leading to difficulties with spatial navigation, balance, speech/language skills, and quality of life when compared with typical hearing peers. Cochlear nerve aplasia and cytomegalovirus are among the most common etiologies for unilateral hearing loss, which has important implications for treatment. Hearing rehabilitation relies upon early correction of hearing loss with an appropriate auditory prosthesis. In children with single-sided deafness, cochlear implants are the only intervention that potentially offers restoration of bilateral hearing, and studies continue to refine candidacy protocols. Unilateral hearing loss has important consequences for children. Recent studies emphasize the importance of early diagnosis and investigate ways to appropriately restore bilateral hearing in these children.

Objectives To examine the effect of aging on electrically evoked compound action potential (eCAP) growth functions and their relationship with speech recognition in noise in cochlear implant (CI) users. Background Aging typically leads to difficulty understanding speech in background noise. Previous research has explored cognitive and central auditory mechanisms contributing to these age-related changes. However, it is likely that the peripheral auditory system may also play a role. One challenge is separating the effects of aging on cochlear structures from the effects of aging on the auditory nerve in humans. CI users provide a unique way to address this issue, as intracochlear electrical stimulation bypasses surviving hair cells and activates the auditory nerve directly. Studies in animal models suggest that age-related loss of spiral ganglion cells could lead to shallower eCAP growth functions and/or increased eCAP thresholds and potentially negatively impact speech recognition. Methods Ten younger and 10 older postlingually deafened, adult CI recipients participated in this study. eCAP amplitude-intensity functions were recorded from a mid-array electrode and fit using linear functions. Speech recognition in noise was assessed using the Quick Speech-in-Noise (QuickSIN) test. Results Older CI users had significantly shallower eCAP growth functions and higher eCAP thresholds than younger CI users. eCAP growth functions were not correlated with speech recognition in noise. Conclusion Results of this study suggest that older adults may have poorer neural survival, resulting in higher eCAP thresholds and shallower eCAP growth functions. These findings expand our understanding of mechanisms underlying age-related changes in the peripheral auditory system.

Single-sided deafness (SSD) is a condition where an individual has non-functional hearing in one ear and receives no clinical benefit from amplification in that ear, with the contralateral ear possessing normal audiometric function. Cochlear implant presents a good choice in rehabilitation of SSD. The presence of a deficient cochlear nerve (CN) has been linked to poor performance with cochlear implants. CN can be measured by imaging techniques. The objective of this study was to compare CN diameter in patients who had a history of single-sided deafness because of sudden hearing loss. Retrospective study where radiologist was blind designed. 53 SSD patients who had a history of sudden hearing loss and MRI at least 5 years after the sudden hearing loss were included in this retrospective study. High-resolution 3-D constructive interference in steady state (CISS)-sequence magnetic resonance (MRI) images was review by the neurotology-experienced blind radiologist. Vertical, horizontal and area measurements of cochlear nerve between the deaf and the normal ear were made. There was no statistically significant difference between the normal ear and deaf ear of the subjects in terms of cochlear nerve vertical diameter, horizontal diameter and area. (respectively, p = 0.250; p = 0.183; p = 0.874) The numbers of remaining cochlear neurons and spiral ganglion cells in the implanted deaf ears are critical and evidence was not found for spiral ganglion cell loss in the sudden hearing loss deaf ear with SSD in MRI. In the light of all these findings, implantation would be a good choice for rehabilitation in postlingual SSD regardless of auditory deprivation duration.

Akbulut, Ahmet Alperen/0000-0002-3273-6632; KARA, Eyyup/0000-0002-4015-4560; Kara, Halide Cetin/0000-0002-6747-7212; Karakol, Sare Nur/0000-0002-3481-5342; Aydin, Kubra/0000-0003-2746-1555 WOS:000531858400018 PubMed ID: 32209515 OBJECTIVES: To evaluate the functions of cochlear structures and the distal part of auditory nerve as well as dead regions within the cochlea in individuals with normal hearing with or without tinnitus by using electrophysiological tests. MATERIALS and METHODS: Nine individuals (ages: 21-59 years) with normal hearing with tinnitus were included in the study group. Thirteen individuals (ages: 25-60 years) with normal hearing without tinnitus were included in the control group. Immitancemetric examination, pure-tone audiometry (125Hz-16kHz), speech audiometry in quiet and noise environments, transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), threshold equalizing noise (TEN test (500Hz-4kHz), and ECochG tests, Beck Depression Questionnaire, Tinnitus Handicap Questionnaire, and Visual Analog Scale were performed. RESULTS:In the study group, three patients were found to have a minimal depression and six were found to have a mild depression. In pure-tone audiometry, the threshold (6-16 kHz) in the study group was significantly higher than that of the control group at all frequencies. In the study group, lower performance scores were obtained in speech discrimination in noise in both ears. In the control group, no dead region was detected in the TEN test whereas 75% of subjects in the study group had dead regions. DPOAE and TEOAE responses between study and control group subjects were not different. In the ECochG test, subjects in the study group showed an increase In the summating potential/action potential (SP/AP) ratio in both ears. CONCLUSION: Determination of the SP/AP ratio in patients with tinnitus may be useful in diagnosing hidden hearing loss. Detection of dead regions in 75% of patients in the TEN test may indicate that inner hair cells may be responsible for tinnitus.

Previous studies have demonstrated that some species of odontocetes can be conditioned to reduce hearing sensitivity when warned of an impending intense sound; however, the underlying mechanisms remain poorly understood. In the present study, conditioned hearing attenuation was elicited in two bottlenose dolphins by pairing a 10-kHz tone (the conditioned stimulus) with a more intense tone (the unconditioned stimulus) at 28 kHz. Testing was performed in air, with sounds presented via contact transducers. Hearing was assessed via noninvasive measurement of monaural auditory nerve responses (ANR) and binaural auditory brainstem responses (ABR). ABRs/ANRs were measured in response to 40-kHz tone bursts, over 2 to 3-s time intervals before and after the conditioned and unconditioned stimuli. Results showed reductions in ABR/ANR amplitude and increases in latency after pairing the warning and more intense tones. Monaural ANRs from the left and right ears were attenuated by similar amounts when the warning and more intense sounds were preferentially applied to the right ear. The data support a neural mechanism operating at the level of the cochlea and/or auditory nerve and suggest the involvement of neural projections that can affect the contralateral ear.

Hearing or/and balance impairments may be caused by disorders of the labyrinthine artery (LA) and their branches. Most findings regarding the LA anatomy have been acquired through investigation of the cerebellopontine angle (CPA) in animal or adult human specimens. Eighty-eight CPAs and LAs of human fetuses were investigated using angio-techniques and microdissections. We found 15 intricate forms of distribution of LA. The LA usually originated from the extra-meatus loop in the anterior inferior cerebellar artery (AICA). The distribution of its terminal branches was 53.42% uni-arterial, 44.31% bi-arterial, and 2.27% tri-arterial systems. In the uni-arterial system, the LA described an anterior superior path to the cochlear nerve (CN) and originated its terminal branches in the gap between CN and the inferior part of the vestibular nerve. In the bi-arterial system, the anterior LA was located anterior and superior to the CN while the posterior LA appeared posterosuperior to the superior part of the vestibular nerve. In the tri-arterial system, the terminal branches originated directly from the AICA loop. Our results provide anatomical support to explain how compressions in the LA branches inside the internal acoustic meatus, as evoked by Schwannomas in the VII and VIII nerves, can lead to hearing and balance loss. The zone of the posterior vestibular nerve appeared to be a "safe area" for invasive procedures in these specimens.

Objective Intraoperative far-field auditory brainstem response (ABR) and direct cochlear nerve action potential monitoring using neural response imaging (NRI) are techniques for monitoring the cochlear nerve during vestibular schwannoma (VS) surgery. A new paradigm has developed where the cochlear nerve is anatomically preserved during tumor removal to facilitate cochlear implantation in select circumstances. This report describes the use of an unmodified commercial cochlear implant (CI) to elicit electrically-evoked direct cochlear nerve and far-field ABR monitoring to evaluate the status of the cochlear nerve during tumor resection in real time. Patients Adult female with unilateral, sporadic VS. Intervention(s) Cochlear implantation followed by translabyrinthine resection of VS in single operation. Main outcome measures During tumor resection intra-cochlear electrodes were used to deliver electrical stimulation and measure NRI or the cochlear nerve action potential. Electrically-evoked ABR (eABR) was measured using surface electrodes and wave V was monitored (far-field ABR) during surgery. Results A 61-year-old female was evaluated for a unilateral, enlarging intracanalicular VS with asymmetric SNHL. The patient opted for microsurgery and due to her bilateral hearing loss was a candidate for CI. Cochlear implantation with an unmodified, commercially available lateral wall electrode was performed. The remainder of the approach and tumor resection was performed under continuous eABR and NRI monitoring. Gross total resection was achieved with intact eABR and NRI at the conclusion of the case. Changes in ABR and NRI consistently recovered after modifying dissection strategy. The patient reported auditory percepts with her cochlear implant postoperatively. Conclusions This report demonstrates the feasibility of using real-time NRI and eABR with a CI to facilitate preservation of the cochlear nerve during VS microsurgery. Using this method to mitigate cochlear nerve trauma during microsurgery may preserve the option of CI for hearing rehabilitation.