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

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

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

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

Preliminary application of combined auditory monitoring technique in resection of vestibular neurinoma / 中华耳鼻咽喉头颈外科杂志

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.

Brainstem auditory evoked potential combined with high resolution cranial base CT can optimize the diagnosis of auditory nerve injury / 中华创伤杂志(英文版)

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.

The imaging characteristics and prognosis of patients with cochlear implants whose cochlear nerves are not shown on MRI / 中华耳鼻咽喉头颈外科杂志

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.

The Effects of Riluzole on Cisplatin-induced Ototoxicity

Abstract Introduction Riluzole (2-amino-6-trifluoromethoxy benzothiazole) is known as a neuroprotective, antioxidant, antiapoptotic agent. It may have beneficial effects on neuronal cell death due to cisplatin-induced ototoxicity. Objective To evaluate the effect of riluzole on cisplatin-induced ototoxicity in guinea pigs. Methods Twenty-four guinea pigs, studied in three groups, underwent auditory brainstem response evaluation using click and 8 kHz tone burst stimuli. Subsequently, 5 mg/kg of cisplatin were administered to all animals for 3 days intraperitoneally (i.p.) to induce ototoxicity. Half an hour prior to cisplatin, groups 1, 2 and 3 received 2 ml of saline i.p., 6 mg/kg of riluzole hydrochloride i.p., and 8 mg/kg of riluzole hydrochloride i.p., respectively, for 3 days. The auditory brainstem responses were repeated 24 hours after the last drug administration. The cochleae were analyzed by transmission electron microscopy (TEM). Results After drug administiration, for 8,000 Hz stimulus, group 1 had significantly higher threshold shifts when compared with groups 2 (p < 0.05) and 3 (p < 0.05), and there was no significant difference in threshold shifts between groups 2 and 3 (p > 0.05). Transmission electron microscopy findings demonstrated the protective effect of riluzole on the hair cells and the stria vascularis, especially in the group treated with 8 mg/kg of riluzole hydrochloride. Conclusion We can say that riluzolemay have a protective effect on cisplatin- induced ototoxicity. However, additional studies are needed to confirm these results and the mechanisms of action of riluzole.

Stem-cell therapy for hearing loss: are we there yet? / Terapia com células-tronco para perda auditiva: já chegamos lá?

Abstract Introduction: Mammalian hair cells and auditory neurons do not show regenerative capacity. Hence, damage to these cell types is permanent and leads to hearing loss. However, there is no treatment that re-establishes auditory function. Regenerative therapies using stem cells represent a promising alternative. Objective: This article aims to review the current literature about the main types of stem cells with potential for application in cell therapy for sensorineural hearing loss, the most relevant experiments already performed in animals, as well as the advances that have been recently made in the field. Methods: Research included the databases PubMed/MEDLINE, Web of Science, Science Direct and SciELO, as well as gray literature. Search strategy included the following main terms: "stem cells", "hair cells" and "auditory neurons". Additionally, the main terms were combined with the following secondary terms: "mesenchymal", "iPS", "inner ear", "auditory". The research was conducted independently by three researchers. Results: Differentiation of stem cells into hair cells and auditory neurons has a high success rate, reaching up to 82% for the first and 100% for the latter. Remarkably, these differentiated cells are able to interact with hair cells and auditory neurons of cochlear explants through formation of new synapses. When transplanted into the cochlea of animals with hearing loss, auditory restoration has been documented to date only in deafferented animals. Conclusion: Advances have been more prominent in cases of auditory neuropathy, since partial improvement of auditory nerve conditions through cell-based therapy may increase the number of patients who can successfully receive cochlear implants.

Resumo Introdução: Nos mamíferos, as células ciliadas e os neurônios auditivos não apresentam capacidade regenerativa. Assim, os danos a esses tipos celulares são permanentes e levam à perda auditiva. Contudo, como não há tratamento que restabeleça a função auditiva, as terapias regenerativas utilizando células-tronco representam uma alternativa promissora. Objetivo: Este artigo tem como objetivo revisar a literatura atual sobre os principais tipos de células-tronco com potencial para aplicação em terapia celular para perda auditiva sensorioneural, os experimentos mais relevantes já realizados em animais, bem como os avanços obtidos recentemente nessa área. Método: As pesquisas incluíram as bases de dados PubMed/MEDLINE, Web of Science, Science Direct e SciELO, além da literatura cinza. A estratégia de busca incluiu os seguintes termos principais: "stem cells", "hair cells" e "auditory neurons". Além disso, os termos principais foram combinados com os seguintes termos secundários: "mesenchymal", "iPS", "inner ear" e "auditory". A pesquisa foi realizada de forma independente por três pesquisadores. Resultados: A diferenciação de células-tronco em células ciliadas e neurônios auditivos têm alta taxa de sucesso, chegando a 82% para o primeiro caso e 100% para o segundo. Notavelmente, essas células diferenciadas são capazes de interagir com células ciliadas e neurônios auditivos de explantes cocleares através da formação de novas sinapses. Quando transplantadas para a cóclea de animais com perda auditiva, a restauração da função auditiva foi observada, até o momento, apenas em animais com ablação do VIII nervo craniano. Conclusão: Os avanços têm sido mais proeminentes em casos de neuropatia auditiva. A melhora parcial das condições do nervo auditivo por meio de terapia baseada em células-tronco pode aumentar o número de pacientes candidatos a receber implantes cocleares com sucesso.

Influence of socioeconomic factors on the perception of cochlear-vestibular symptoms and adherence to the treatment of congenital hypothyroidism / Influência dos fatores socioeconômicos na percepção de sintomas cócleo-vestibulares e na adesão ao tratamento do hipotireoidismo congênito

Abstract Objectives: to verify if there is an association between socioeconomic factors and adherence to treatment in congenital hypothyroidism and to verify if there is an association between socioeconomic factors and vestibulocochlear symptoms noticed by parents/caregivers of children diagnosed with congenital hypothyroidism. Methods: a cross-sectional, exploratory and descriptive study, with a convenience sample. The sample consisted of 108 children with clinical and laboratory diagnosis of congenital hypothyroidism, of both sexes, aged ≥ 5 years. The researchers applied a structured questionnaire to parents/caregivers, consisting of closed and objective questions about the presence or absence of tinnitus, hearing loss and dizziness/vertigo in children with congenital hypothyroidism. Results: There was no association between socioeconomic factors and adherence to treatment or perception of cochlear-vestibular symptoms. Conclusions: socioeconomic factors did not influence treatment adherence or perceived cochlear-vestibular symptoms by caregivers of children with congenital hypothyroidism.

Resumo Objetivos: verificar se existe associação entre fatores socioeconômicos e adesão ao tratamento no hipotireoidismo congênito e verificar se existe associação entre fatores socioeconômicos e sintomas vestibulococleares percebidos pelos pais / cuidadores de crianças diagnosticadas com hipotireoidismo congênito. Métodos: estudo transversal, exploratório e descritivo, com amostra de conveniência. A casuística foi composta por 108 crianças com diagnóstico clínico e laboratorial de hipotireoidismo congênito, de ambos os sexos com idade ≥ 5 anos. Foi aplicado um questionário estruturado para os pais/cuidadores, formado por questões fechadas e objetivas sobre a presença ou ausência de zumbido, hipoacusia e tontura/vertigem nas crianças com hipotireoidismo congênito. Resultados: não houve associação entre fatores socioeconômicos e adesão ao tratamento ou percepção dos sintomas cócleo-vestibulares. Conclusões: os fatores socioeconômicos não influenciaram na adesão ao tratamento nem na percepção de sintomas cócleo-vestibulares pelos cuidadores de crianças com hipotireoidismo congênito.

Case Series Outcomes of Cochlear Implantation in Children with Noonan Syndrome / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Hearing loss is a common complication associated with Noonan syndrome (NS), and the level of hearing loss for NS patients with sensorineural loss ranged from normal to severe. Additional insights into the outcome of cochlear implantation (CI)in children with NS with or without comorbidities are needed. SUBJECTS AND METHOD: In this study, five patients with NS, four with a mutation in PTPN11 and one who tested negative in mutation screening, diagnosed with the clinical scoring systemand underwent CI at ages ranging from 16 to 50 months were retrospectively reviewed. Patientswere evaluated for auditory perception (Categories of Auditory Performance), speech production (Korean Version of the Ling's Stage), and language ability (Receptive and Expressive Vocabulary Test). RESULTS: In five of the children with NS, CI was performed without any complications. Threepatients who received CI before 30 months of age showed outstanding outcomes. One patientwho received CI at 50 months showed limited benefit. One patient who was diagnosed with developmental delay and cochlear nerve hypoplasia underwent CI at 28 months with poor outcome. DISCUSSION: Our report suggests that although the benefit may be influenced by comorbidities associated with NS or delay in hearing rehabilitation, profound hearing loss in patientswith NS may be restored to normal levels in terms of auditory/speech perception and vocabulary/language development. The variable hearing outcomes also underscore the need for earlyscreening and detection of profound hearing loss, and regular follow-up for hearing evaluationin patients with NS.

Duplicated Internal Auditory Canal: High-Resolution CT and MRI Findings

OBJECTIVE: To summarize the high-resolution computed tomography (HRCT) and magnetic resonance imaging (HRMRI) features of duplicated internal auditory canals (DIACs). MATERIALS AND METHODS: Ear HRCT data of 64813 patients with sensorineural hearing loss (SNHL), obtained between August 2009 and November 2017, were reviewed. Among these patients, 12 (13 ears) were found to have DIACs, 9 of whom underwent HRMRI. Their images were evaluated by two otoradiologists. RESULTS: The rate of occurrence of DIAC among SNHL patients was 0.019% (12/64813). The internal auditory canals of 13 ears were divided into double canals by complete (n = 6) and incomplete (n = 7) bony septa, with varied orientations ranging from horizontal to approximately vertical. All of the anterosuperior canals extended into the facial nerve (FN) canal, except for 1, which also extended to the vestibule. The posteroinferior canals ended in the cochlea and vestibule, except for 2, which also connected to the FN canals. Magnetic resonance images revealed that 77.8% (7/9) and 22.2% (2/9) of vestibulocochlear nerves (VCNs) were aplastic and hypoplastic, respectively. Furthermore, 88.9% (8/9) of FNs were normal, except for 1, which was hypoplastic. All of the affected ears also had other ear anomalies: a narrow, bony cochlear nerve canal was the most common other anomaly, accounting for 92.3% (12/13). Malformations of other systems were not found. CONCLUSION: Double-canal appearance is a characteristic finding of DIAC on HRCT, and it is usually accompanied by other ear anomalies. The VCN usually appears aplastic, with a normal FN, on HRMRI.

The maturation state of the auditory nerve and brainstem in rats exposed to lead acetate and supplemented with ferrous sulfate / Estado de maturação do nervo auditivo e tronco encefálico em ratos expostos a acetato de chumbo e suplementados com sulfato ferroso

Abstract Introduction The literature has reported the association between lead and auditory effects, based on clinical and experimental studies. However, there is no consensus regarding the effects of lead in the auditory system, or its correlation with the concentration of the metal in the blood. Objective To investigate the maturation state of the auditory system, specifically the auditory nerve and brainstem, in rats exposed to lead acetate and supplemented with ferrous sulfate. Methods 30 weanling male rats (Rattus norvegicus, Wistar) were distributed into six groups of five animals each and exposed to one of two concentrations of lead acetate (100 or 400 mg/L) and supplemented with ferrous sulfate (20 mg/kg). The maturation state of the auditory nerve and brainstem was analyzed using Brainstem Auditory Evoked Potential before and after lead exposure. The concentration of lead in blood and brainstem was analyzed using Inductively Coupled Plasma-Mass Spectrometry. Results We verified that the concentration of Pb in blood and in brainstem presented a high correlation (r = 0.951; p < 0.0001). Both concentrations of lead acetate affected the maturation state of the auditory system, being the maturation slower in the regions corresponding to portion of the auditory nerve (wave I) and cochlear nuclei (wave II). The ferrous sulfate supplementation reduced significantly the concentration of lead in blood and brainstem for the group exposed to the lowest concentration of lead (100 mg/L), but not for the group exposed to the higher concentration (400 mg/L). Conclusion This study indicate that the lead acetate can have deleterious effects on the maturation of the auditory nerve and brainstem (cochlear nucleus region), as detected by the Brainstem Auditory Evoked Potentials, and the ferrous sulphate can partially amend this effect.

Resumo Introdução A literatura relatou a associação entre o chumbo e os efeitos auditivos, com base em estudos clínicos e experimentais. No entanto, não há consenso em relação aos efeitos do chumbo no sistema auditivo, ou sua correlação com a concentração do metal no sangue. Objetivo Investigar o estado de maturação do sistema auditivo, especificamente do nervo auditivo e do tronco encefálico, em ratos expostos ao acetato de chumbo e suplementados com sulfato ferroso. Método 30 ratos machos desmamados (Rattus norvegicus, Wistar) foram distribuídos em seis grupos de cinco animais e expostos a uma de duas concentrações de acetato de chumbo (100 ou 400 mg/L) e suplementados com sulfato ferroso (20 mg/kg). O estado de maturação do nervo auditivo e do tronco encefálico foi analisado pelo Potencial Evocado Auditivo do Tronco Encefálico antes e após a exposição ao chumbo. A concentração de chumbo no sangue e tronco encefálico foi analisada utilizando-se Espectrometria de Massa com Plasma Indutivamente Acoplado. Resultados Verificamos que as concentrações de Pb no sangue e no tronco encefálico apresentaram alta correlação (r = 0,951, p < 0,0001). Ambas as concentrações de acetato de chumbo afetaram o estado de maturação do sistema auditivo, a maturação foi mais lenta nas regiões correspondentes à porção do nervo auditivo (onda I) e dos núcleos cocleares (onda II). A suplementação com sulfato ferroso reduziu significativamente a concentração de chumbo no sangue e no tronco encefálico no grupo exposto à menor concentração de chumbo (100 mg/L), mas não para o grupo exposto à maior concentração (400 mg/L). Conclusão Esse estudo indica que o acetato de chumbo pode ter efeitos deletérios na maturação do nervo auditivo e do tronco encefálico (região do núcleo coclear), como detectado pelos potenciais evocados auditivos do tronco encefálico, e que o sulfato ferroso pode diminuir parcialmente esse efeito.

Computed Tomography and Magnetic Resonance Imaging Evaluation in Pediatric Unilateral Sensorineural Hearing Loss / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Children with unilateral sensorineural hearing loss (USNHL) are not actively evaluated by physicians. The diagnostic tool for evaluation of USNHL is also controversial, and no strategy for diagnosing USNHL through imaging studies has been established. We examined the results of temporal bone computed tomography (TBCT) imaging and magnetic resonance imaging (MRI) studies on children with USNHL. SUBJECTS AND METHOD: Eighty-nine patients with USNHL were reviewed. Of these patients, 21 underwent both TBCT and MRI, 51 underwent temporal MRI only, and 17 underwent TBCT only. RESULTS: The etiology of USNHL were determined through imaging studies in 20 patients. The most common abnormal finding (65%) was a narrow internal auditory canal identified on TBCT and cochlear nerve aplasia on temporal MRI. Incomplete partition (20%), common cavity (10%), and labyrinthitis ossificans (5%) were also observed in imaging studies. The hearing threshold was lower in USNHL patients with normal findings (76.1±28.7 dB) than in USNHL patients with abnormal findings on TBCT or temporal MRI (100.1±22.3 dB). CONCLUSION: Cochlear and cochlear nerve abnormalities can be detected through imaging studies in approximately 25% of patients with USNHL. Therefore, we suggest that children should undergo TBCT when USNHL is confirmed through audiologic evaluation.

Safety of Autologous Umbilical Cord Blood Therapy for Acquired Sensorineural Hearing Loss in Children

BACKGROUND AND OBJECTIVES: Sensorineural hearing loss (SNHL) in children is associated with neurocognitive morbidity. The cause of SNHL is a loss of hair cells in the organ of Corti. There are currently no reparative treatments for SNHL. Numerous studies suggest that cord blood mononuclear cells (human umbilical cord blood, hUCB) allow at least partial restoration of SNHL by enabling repair of a damaged organ of Corti. Our objective is to determine if hUCB is a safe treatment for moderate to severe acquired SNHL in children. SUBJECTS AND METHODS: Eleven children aged 6 months to 6 years with moderate to severe acquired SNHL were treated with intravenous autologous hUCB. The cell dose ranged from 8 to 30 million cells/kg body weight. Safety was assessed by measuring systemic hemodynamics during hUCB infusion. Infusion-related toxicity was evaluated by measuring neurologic, hepatic, renal and pulmonary function before and after infusion. Auditory function, auditory verbal language assessments and MRI with diffusion tensor imaging (DTI) were obtained before and after treatment. RESULTS: All patients survived, and there were no adverse events. No infusionrelated changes in hemodynamics occurred. No infusion-related toxicity was recorded. Five subjects experienced a reduction in auditory brainstem response (ABR) thresholds. Four of those 5 subjects also experienced an improvement in cochlear nerve latencies. Comparison of MRI with DTI sequences obtained before and after treatment revealed increased fractional anisotropy in the primary auditory cortex in three of five subjects with reduced ABR thresholds. Statistically significant (p < 0.05) reductions in ABR thresholds were identified. CONCLUSIONS: TIntravenous hUCB is feasible and safe in children with SNHL.

Ototoxicity: A Challenge in Diagnosis and Treatment

Ototoxicity is the pharmacological adverse reaction affecting the inner ear or auditory nerve, characterized by cochlear or vestibular dysfunction. The panorama of drug-induced hearing loss has widened over last few decades. Although ototoxic medications play an imperative role in modern medicine, they have the capacity to cause harm and lead to significant morbidity. Evidence has shown early detection of toxicity through prospective ototoxicity monitoring allows for consideration of treatment modifications to minimize or prevent permanent hearing loss and balance impairment. Although many ototoxicity monitoring protocols exist, their practicality is questionable due to several factors. Even though the existing protocols have proven to be effective, certain lacunae in practice have been encountered due to discrepancies among recommended protocols. Implementation of these protocols is mostly held back due to the incapacitated status of the patient. The choice of early ototoxicity identification techniques is still debatable due to variables such as high degree of sensitivity, specificity and reliability, less time consumption and less labour-intensive to the patient. Hence, the diagnosis and effective treatment of ototoxicity is challenging, even today. A stringent protocol with more practicality encompassing all elements aimed at profiling the effects of ototoxicity is greatly needed. This review describes an efficient application of ototoxicity monitoring and treatment protocol as an attempt to reduce the challenges in diagnosis and management of ototoxicity.

A rare case of isolated schwannoma in infraorbital nerve

A schwannoma is a benign tumor that develops from Schwann cells. It is known to occur more frequently in women than men, and about one third of schwannoma cases occur in the head and neck area. It is also known to originate mainly in the auditory nerve. However, it is rarely associated with the trigeminal nerve, and especially, schwannomas related to the infraorbital nerve are very rare. we report a rare case of a schwannoma involving the infraorbital branch of the trigeminal nerve in a 45-year old male adult. The patient underwent physical examination and magnetic resonance imaging. The mass was approached through subciliary approach that is familiar to the plastic surgeon and completely resected. Histopathological findings showed pointed to a benign schwannoma. Infraorbital nerve schwannoma is difficult to distinguish from other diseases by means of clinical symptoms, physical findings, or imaging. In spite of its rarity, infraorbital nerve schwannoma may be considered a possible diagnosis in the case of mass on cheek. Assessment by computed tomography or magnetic resonance imaging is necessary for proper diagnosis. About the surgical approach, excision through the subciliary approach should be considered rather than the direct transfacial approach in view of stability, cosmetic effects, and familiarity.

Two Cases of Electrode Kinking in Cochlear Implantation / 대한이비인후과학회지

Less traumatic electrode insertion along the basal turn of cochlea is essential to cochlear implantation. However, immoderate attempts to insert the electrode beyond the point of resistance can result in electrode kinking within the basal turn of cochlea. Electrode kinking tends to occur 1) in the use of contour or hugging type of electrode, 2) in the cochlear ossification or fibrosis, and 3) in wrong angle insertion in the approach of round window membrane or cochleostomy near the round window. Intra-operative radiologic evaluation and intra-operative measurement of the neural response telemetry or auditory nerve response telemetry during cochlear implantation is essential to check the status and proper insertion of electrode. Recently, we experienced two cases of electrode kinking in cochlear implantation and discovered that both patients showed abnormal impedances and crumpled electrode in X-ray. Based on these cases, we suggest routine impedance and radiologic measurement during the cochlear implantation.

Deficiencia del nervio coclear: logros obtenidos y expectativas con el implante coclear / Coclear nerve deficiency: achievements and expectations with the coclear implant / Deficiência de nervos coculares: realizações e expectativas como implante cocular

Introducción: la deficiencia del nervio coclear se define como un nervio coclear hipoplásico o aplásico, presente en más del 18% de los niños con hipoacusias neurosensoriales profundas y cuya indicación de implante coclear sigue generando controversias. Objetivo: Analizar el protocolo de estudio en pacientes con sospecha de deficiencia del nervio coclear y exponer los resultados clínico-audiológicos pos-implante coclear en nuestro servicio. Material y método: Estudio retrospectivo de historias clínicas en el período 2011-2017, analizando los estudios solicitados dentro de la evaluación preimplante coclear y el estudio extendido en pacientes con sospecha de deficiencia del nervio coclear. Resultados: Dentro de la población, un caso correspondió a un paciente con hipoacusia neurosensorial profunda bilateral con sospecha de deficiencia del nervio coclear (Birman: GRADO I y Casselman: TIPO I/IIa bilateral). El potencial evocado auditivo de tronco encefálico eléctrico permitió determinar el oído a implantar, mostrando mejor configuración de ondas para el oído derecho. Actualmente, presenta una óptima adaptación al implante (categoría de performance auditivo: 2-categoría de Moog-Geers: 3), con una puntuación de 8/40 en el cuestionario IT-MAIS. Conclusión: El protocolo de estudio prequirúrgico extendido es aplicable a pacientes con sospecha de deficiencia del nervio coclear. Estudios funcionales aportan datos de utilidad para determinar cuál de estos pacientes podrían beneficiarse tras la colocación del mismo. El asesoramiento familiar sobre las limitaciones y los objetivos reales es fundamental.

Introduction: cochlear nerve deficiency is defined as a hypoplastic or aplastic cochlear nerve present in more than 18% of children with profound sensorineural hearing loss. Cochlear implant indication continues to generate controversy. Objective: Analyze the study protocol in patients with suspected cochlear nerve deficiency and expose the clinical-audiological results after cochlear implant in our service. Material and method: Retrospective study of medical records in the period 2011-2017. Analyzing the studies requested within the cochlear pre-implant evaluation and the extended study in patients with suspected cochlear nerve deficiency. Results: Within the population, one case corresponded to a patient with bilateral profound sensorineural hearing loss with suspicion of Cochlear nerve deficiency (Birman GRADE I and Casselman TYPE I/IIa bilateral). The auditory evoked potentials by electrical stimulation allowed to determine the ear to be implanted, showing better configuration of waves for the right ear. Currently, it presents an optimal adaptation to the implant (Auditory per formance category: 2- Category of Moog-Geers: 3), with a score of 8/40 in the IT-MAIS questionnaire. Conclusion: The extended preoperative study protocol is appropriate for patients with suspected cochlear nerve deficiency. Functional studies provide useful data to determine which patients could benefit. Family counseling about real limitations and goals is critical.

Introdução: a deficiência do nervo coclear é definida como um nervo coclear hipoplásico ou aplástico presente em mais de 18% das crianças com perda auditiva neurossensorial profunda onde a indicação do implante coclear continua a gerar polêmica. Objetivo: Analisar o protocolo do estudo em pacientes com suspeita de deficiência do nervo coclear e apresentar os resultados clínico-audiológicos após o implante coclear em nosso serviço. Material e método: Estudo retrospectivo dos registros clínicos no período de 2011-2017, analisando os estudos solicitados na avaliação pré-implante coclear e o estudo prolongado em pacientes com suspeita de deficiência de nervo coclear. Resultados: Dentro da população, um caso correspondeu a um paciente com perda auditiva neurossensorial profunda bilateral com suspeita de deficiência do nervo coclear (Birman: GRADO I e Casselman: TIPO bilateral I/IIa). O potenciais evocados auditivos elétrico permitiu determinar a orelha a ser implantada, mostrando melhor configuração de ondas para a orelha direita. Atualmente, apresenta uma ótima adaptação ao implante (categoria de desempenho auditivo: 2- categoria de Moog-Geers: 3), com uma pontuação de 8/40 no questionário IT-MAIS. Conclusão: O protocolo de estudo pré-operatório estendido é aplicável a pacientes com suspeita de deficiência do nervo coclear. Estudos funcionais fornecem dados úteis para determinar quais pacientes poderiam se beneficiar do implante coclear. O aconselhamento familiar sobre limitações e metas reais é crítico.

Analysis of electrically evoked compound action potential of the auditory nerve in children with bilateral cochlear implants / Análise do potencial de ação composto do nervo auditivo evocado eletricamente em crianças usuárias de implante coclear bilateral

ABSTRACT INTRODUCTION: The cochlear implant device has the capacity to measure the electrically evoked compound action potential of the auditory nerve. The neural response telemetry is used in order to measure the electrically evoked compound action potential of the auditory nerve. OBJECTIVE: To analyze the electrically evoked compound action potential, through the neural response telemetry, in children with bilateral cochlear implants. METHODS: This is an analytical, prospective, longitudinal, historical cohort study. Six children, aged 1-4 years, with bilateral cochlear implant were assessed at five different intervals during their first year of cochlear implant use. RESULTS: There were significant differences in follow-up time (p = 0.0082) and electrode position (p = 0.0019) in the T-NRT measure. There was a significant difference in the interaction between time of follow-up and electrode position (p = 0.0143) when measuring the N1-P1 wave amplitude between the three electrodes at each time of follow-up. CONCLUSION: The electrically evoked compound action potential measurement using neural response telemetry in children with bilateral cochlear implants during the first year of follow-up was effective in demonstrating the synchronized bilateral development of the peripheral auditory pathways in the studied population.

RESUMO INTRODUÇÃO: O implante coclear tem a capacidade de medir o potencial de ação composto eletricamente evocado do nervo auditivo (ECAP). Para esta verificação utiliza-se uma medida chamada telemetria de respostas neurais. OBJETIVO: Analisar o potencial de ação composto evocado eletricamente, por meio da neurotelemetria de respostas neurais, em crianças usuárias de implante coclear bilateral. MÉTODO: Trata-se de um estudo analítico, prospectivo, de coorte histórica longitudinal. Foram recrutadas seis crianças, com idades entre de 1-4 anos, usuárias de implante coclear bilateral. Estas crianças foram avaliadas em cinco momentos durante o primeiro ano de uso do implante coclear. RESULTADOS: Houve diferença significativa no tempo de acompanhamento (p = 0,0082) e posição do eletrodo (p = 0,0019) na medida de T-NRT. Houve diferença significativa na interação entre tempo de acompanhamento e posição do eletrodo (p = 0,0143) na medida da amplitude das ondas N1-P1 entre os três eletrodos a cada tempo de acompanhamento. CONCLUSÃO: A mensuração do ECAP por meio da NRT nas crianças com implante coclear bilateral durante o primeiro ano de acompanhamento foi uma medida importante para apresentar o desenvolvimento bilateral da via auditiva periférica de forma sincronizada nesta população estudada.

Prediction of Cochlear Implant Outcomes in Patients With Prelingual Deafness

OBJECTIVES: To evaluate the factors that limit post-cochlear implantation (CI) speech perception in prelingually deaf children. METHODS: Patients with CI were divided into two groups according to Category of Auditory Performance (CAP) scores 3 years post-CI: the poor performance group (poor performance group, CAP scores≤4, n=41) and the good performance group (good performance group, CAP scores≥5, n=85). The distribution and contribution of the potential limiting factors related to post-CI speech perception was compared. RESULTS: Perinatal problems, inner ear anomalies, narrow bony cochlear nerve canal (BCNC), and intraoperative problems was significantly higher in the poor performance group than the good performance group (P=0.010, P=0.003, P=0.001, and P=0.045, respectively). The mean number of limiting factors was significantly higher in the poor performance group (1.98±1.04) than the good performance group (1.25±1.11, P=0.001). The odds ratios for perinatal problems and narrow bony cochlear nerve canal in the poor performance group in comparison with the good performance group were 4.878 (95% confidence interval, 0.067 to 0.625; P=0.005) and 4.785 (95% confidence interval, 0.045 to 0.972; P=0.046). CONCLUSION: This study highlights the comprehensive prediction of speech perception after CI and provides otologic surgeons with useful information for individualized preoperative counseling of CI candidates.

Simultaneous Translabyrinthine Tumor Removal and Cochlear Implantation in Vestibular Schwannoma Patients

Refinement of surgical techniques has allowed hearing preservation after tumor resection to be prioritized. Moreover, restoration of hearing after tumor removal can be attempted in patients with bilateral vestibular schwannomas or those with a schwannoma in the only-hearing ear. Cochlear implantation (CI) has emerged as a proper method of acoustic rehabilitation, provided that the cochlear nerve remains intact. Studies of electrical promontory stimulation in patients after vestibular schwannoma resection have demonstrated favorable results. We describe herein two cases of hearing rehabilitation via CI implemented at the time of vestibular schwannoma resection. Tumors were totally removed, and cochlear implant electrodes were successfully inserted in both cases. Also, post operative CI-aided hearing showed improved results.