Hearing and Hearing Loss Progression in Patients with GJB2 Gene Mutations: A Long-Term Follow-Up.

We aimed to investigate whether the degree of hearing loss with GJB2 mutations could be predicted by distinguishing between truncating and non-truncating mutations and whether the genotype could predict the hearing loss level. Additionally, we examined the progression of hearing loss in individuals monitored for over 2 years for an average of 6.9 years. The proportion of truncating mutations was higher in patients with profound and severe hearing loss, but it was not accurate enough to predict the degree of hearing loss. Via genotype analysis, mutations of the p.Arg143Trp variants were associated with profound hearing loss, while mutations of the p.Leu79Cysfs*3 allele exhibited a wide range of hearing loss, suggesting that specific genotypes can predict the hearing loss level. Notably, there were only three cases of progression in four ears, all of which involved the p.Leu79Cysfs*3 mutation. Over the long-term follow-up, 4000 Hz was significant, and there was a trend of progression at 250 Hz, suggesting that close monitoring at these frequencies during follow-up may be crucial to confirm progression. The progression of hearing loss was observed in moderate or severe hearing loss cases at the time of the initial diagnosis, emphasizing that children with this level of hearing loss need regular follow-ups.

Stereotactic radiosurgery ensures an effective and safe long-term control of Koos grade IV vestibular schwannomas: a single-center, retrospective, cohort study.

PURPOSE: Stereotactic radiosurgery (SRS) is a standard treatment modality for vestibular schwannomas (VSs). However, there is a paucity of data on tumor control and neurological preservation for larger VSs. We aimed to investigate the long-term effectiveness of SRS for Koos grade IV compared with I-III VSs. METHODS: We included 452 patients with VSs (50 Koos grade IV and 402 Koos grade I‒III) who were treated with SRS at our institution from 1990 to 2021. Tumor control and functional preservation were calculated using the Kaplan-Meier method and compared between groups with the log-rank test. RESULTS: The median post-SRS follow-up period was 68 months. Progression-free survival rates were 91% at 5 and 10 years for Koos grade IV VSs, and 95% and 92%, respectively, for Koos grade I‒III VSs (p = 0.278). In Koos grade IV VSs, functional preservation rates of the facial and trigeminal nerves were both 96% at 5 years (both 98% for Koos grade I‒III VSs; facial, p = 0.410; trigeminal, p = 0.107). Hearing preservation rates were 61% at 5 years for Koos grade IV VSs and 78% for Koos grade I-III VSs (p = 0.645). Symptomatic transient tumor expansion was more common with Koos grade IV VSs (8.0% vs. 2.5%, p = 0.034), although all related symptoms diminished in accordance with tumor shrinkage. CONCLUSION: SRS may contribute to long-term tumor control and adequate neurological preservation in the treatment of Koos grade IV VSs, comparable to those in the treatment of Koos grade I‒III VSs.

Macrophage recruitment, but not interleukin 1 beta activation, enhances noise-induced hearing damage.

It has been suggested that macrophages or inflammatory monocytes participate in the pathology of noise-induced hearing loss (NIHL), but it is unclear how extensively these cells contribute to the development of temporary and/or permanent NIHL. To address this question, we used clodronate liposomes to deplete macrophages and monocytes. After clodronate liposome injection, mice were exposed to 4-kHz octave band noise at 121 dB for 4 h. Compared to vehicle-injected controls, clodronate-treated mice exhibited significantly reduced permanent threshold shifts at 4 and 8 kHz and significantly smaller outer hair cell losses in the lower-apical cochlear turn. Following noise exposure, the stria vascularis had significantly more cells expressing the macrophage-specific protein F4/80, and this effect was significantly suppressed by clodronate treatment. These F4/80-positive cells expressed interleukin 1 beta (IL-1ß), which noise exposure activated. However, IL-1ß deficient mice did not exhibit significant resistance to intense noise when compared to wild-type mice. These findings suggest that macrophages that enter the cochlea after noise exposure are involved in NIHL, whereas IL-1ß inhibition does not reverse this cochlear damage. Therefore, macrophages may be a promising therapeutic target in human sensorineural hearing losses such as NIHL.

Exploring the Source of Neural Responses of Different Latencies Obtained from Different Recording Electrodes in Cochlear Implant Users.

In this study we measured the electrically evoked compound action potential (ECAP) from different recording electrodes in the cochlea. Under the assumption that different response latencies may be the result of differences in the neural population contributing to the response, we assessed the relationship between neural response latency and spread of excitation. First, we evaluated changes in N1 latency when the recording electrode site was varied. Second, we recorded channel interaction functions using a forward masking technique but with recording electrodes at different intracochlear locations. For most individuals, N1 latency was similar across recording electrodes. However, reduced N1 latencies were observed in 21% of cochlear implant users when ECAPs were recorded using a remote recording electrode. We hypothesized that if recordings from different electrodes represented contributions from different populations of neurons, then one might expect that channel interaction functions would be different. However, we did not observe consistent differences in channel interaction functions (neither peak location nor breadth of the functions), and further, any variation in channel interaction functions was not correlated with ECAP latency. These results suggest that ECAPs from different recording electrodes with different latencies originate from similar neural populations.

Age-related morphological changes in the basement membrane in the stria vascularis of C57BL/6 mice.

Basement membrane anionic sites (BMAS) are involved in the selective transport of electrically charged macromolecules in cochlear capillaries. Using cationic polyethyleneimine (PEI), we examined age-related changes in BMAS in the cochleae of C57BL/6 mice. The mice were grouped according to age as follows: 3 days, 4 weeks, 8 weeks, 6 months, and 12 months. In the right bony labyrinths, widths of the stria vascularis were measured in paraffin-embedded sections using light microscopy. The left bony labyrinths were immersed in a 0.5 % cationic PEI solution and embedded in epoxy resin. Ultrathin sections of the left cochlea were examined using transmission electron microscopy. A significant difference in stria vascularis width was observed between the 4-week-old and 12-month-old mice. The PEI distribution in the capillary and epithelial basement membranes (BMs) of the cochlea was observed. In all animals, PEI particles were evenly distributed in the capillary BM of the spiral ligament and in the subepithelial BM of Reissner's membrane. In the stria vascularis, PEI particles were evenly distributed in the capillary BM in 3-day-old mice. In 4- and 8-week-old mice, PEI particle sizes were markedly lower than those observed in 3-day-old mice. In 6- and 12-month-old mice, PEI particles were hardly detected in the strial capillary BM. In the strial capillary BM in these mice, the laminae rarae externa and interna disappeared, but the lamina densa became larger. We speculated that age-related changes of strial capillary BMAS may affect electrically charged macromolecule transport systems in the stria vascularis of C57BL/6 mice.

Prediction of Cochlear Implant Fitting by Machine Learning Techniques.

OBJECTIVE: This study aimed to evaluate the differences in electrically evoked compound action potential (ECAP) thresholds and postoperative mapping current (T) levels between electrode types after cochlear implantation, the correlation between ECAP thresholds and T levels, and the performance of machine learning techniques in predicting postoperative T levels. STUDY DESIGN: Retrospective case review. SETTING: Tertiary hospital. PATIENTS: We reviewed the charts of 124 ears of children with severe-to-profound hearing loss who had undergone cochlear implantation. INTERVENTIONS: We compared ECAP thresholds and T levels from different electrodes, calculated correlations between ECAP thresholds and T levels, and created five prediction models of T levels at switch-on and 6 months after surgery. MAIN OUTCOME MEASURES: The accuracy of prediction in postoperative mapping current (T) levels. RESULTS: The ECAP thresholds of the slim modiolar electrodes were significantly lower than those of the straight electrodes on the apical side. However, there was no significant difference in the neural response telemetry thresholds between the two electrodes on the basal side. Lasso regression achieved the most accurate prediction of T levels at switch-on, and the random forest algorithm achieved the most accurate prediction of T levels 6 months after surgery in this dataset. CONCLUSION: Machine learning techniques could be useful for accurately predicting postoperative T levels after cochlear implantation in children.

Cochlear implantation for progressive hearing loss caused by an A8296G mutation in mitochondrial DNA.

Mitochondrial DNA mutations such as A3243G or A1555G are widely reported to cause hearing loss, but few reports exist on the A8296G mutation, which can also cause hearing loss. This report presents the case of a patient with the A8296G mutation and severe bilateral sensorineural hearing loss (SNHL) that progressed over two decades. The patient had no history of diabetes, but did have a family history of SNHL in her father and maternal grandmother. She was first diagnosed with SNHL at 45 years of age, and an A8296G mutation was found. The hearing threshold in the low-frequency range of the right ear was preserved at diagnosis, but eventually declined resulting in severe bilateral hearing loss by the age of 66 years, and cochlear implantation (CI) was performed in the left ear. The hearing threshold three months after CI was 25-45 dB HL, and the phoneme speech discrimination score in the left ear improved from 20% without CI to 74% with CI. SNHL patients with the A8295G mutation are good candidates for treatment with CI.

A Randomized Crossover Study in Single-Sided Deafness Comparing a Cartilage Conduction CROS System and an Air-Conduction CROS System.

OBJECTIVE: To investigate if cartilage conduction (CC) rerouting devices are noninferior to air-conduction (AC) rerouting devices for single-sided deafness (SSD) patients by measuring objective and subjective performance using speech-in-noise tests that resemble a realistic hearing environment, sound localization tests, and standardized questionnaires. STUDY DESIGN: Prospective, single-subject randomized, crossover study. SETTING: Anechoic room inside a university. PATIENTS: Nine adults between 21 and 58 years of age with severe or profound unilateral sensorineural hearing loss. INTERVENTIONS: Patients' baseline hearing was assessed; they then used both the cartilage conduction contralateral routing of signals device (CC-CROS) and an air-conduction CROS hearing aid (AC-CROS). Patients wore each device for 2 weeks in a randomly assigned order. MAIN OUTCOME MEASURES: Three main outcome measures were 1) speech-in-noise tests, measuring speech reception thresholds; 2) proportion of correct sound localization responses; and 3) scores on the questionnaires, "Abbreviated Profile of Hearing Aid Benefit" (APHAB) and "Speech, Spatial, and Qualities of Hearing Scale" with 12 questions (SSQ-12). RESULTS: Speech reception threshold improved significantly when noise was ambient, and speech was presented from the front or the poor-ear side with both CC-CROS and AC-CROS. When speech was delivered from the better-ear side, AC-CROS significantly improved performance, whereas CC-CROS had no significant effect. Both devices mainly worsened sound localization, whereas the APHAB and SSQ-12 scores showed benefits. CONCLUSION: CC-CROS has noninferior hearing-in-noise performance except when the speech was presented to the better ear under ambient noise. Subjective measures showed that the patients realized the effectiveness of both devices.

Prediction of Cochlear Implant Effectiveness With Surface-Based Morphometry.

OBJECTIVE: This study aimed to determine whether surface-based morphometry of preoperative whole-brain three-dimensional T1-weighted magnetic resonance imaging (MRI) images can predict the clinical outcomes of cochlear implantation. STUDY DESIGN: This was an observational, multicenter study using preoperative MRI data. SETTING: The study was conducted at tertiary care referral centers. PATIENTS: Sixty-four patients with severe to profound hearing loss (≥70 dB bilaterally), who were scheduled for cochlear implant (CI) surgery, were enrolled. The patients included 19 with congenital hearing loss and 45 with acquired hearing loss. INTERVENTIONS: Participants underwent CI surgery. Before surgery, high-resolution three-dimensional T1-weighted brain MRI was performed, and the images were analyzed using FreeSurfer. MAIN OUTCOME MEASURES: The primary outcome was monosyllable audibility under quiet conditions 6 months after surgery. Cortical thickness residuals within 34 regions of interest (ROIs) as per the Desikan-Killiany cortical atlas were calculated based on age and healthy-hearing control regression lines. RESULTS: Rank logistic regression analysis detected significant associations between CI effectiveness and five right hemisphere ROIs and five left hemisphere ROIs. Predictive modeling using the cortical thickness of the right entorhinal cortex and left medial orbitofrontal cortex revealed a significant correlation with speech discrimination ability. This correlation was higher in patients with acquired hearing loss than in those with congenital hearing loss. CONCLUSIONS: Preoperative surface-based morphometry could potentially predict CI outcomes and assist in patient selection and clinical decision making. However, further research with larger, more diverse samples is necessary to confirm these findings and determine their generalizability.

Evaluation of the internal structure of normal and pathological Guinea pig cochleae using optical coherence tomography.

Optical coherence tomography (OCT) makes it possible to visualize the internal structures of several organs, such as the eye, in vivo. Although visualization of the internal structures of the inner ear has been used to try and identify certain pathological conditions, attempts have failed mainly due to the thick bony capsule surrounding this end organ. After decalcifying the bony wall of the cochlea with ethylenediamine tetraacetic acid, we could clearly visualize its internal structures by using OCT. We identified endolymphatic hydrops, strial atrophy and damage to the organ of Corti, evident as a distention of Reissner's membrane, thinning of the lateral wall and flattening of the organ of Corti, respectively. When specimens embedded in paraffin, sliced and stained with hematoxylin and eosin (HE) were examined under a light microscope, the OCT images of normal and pathological cochleae were virtually identical with those of the HE specimens, except that the HE specimens exhibited several artifacts unrecognized in OCT images, which were considered to be induced during the preparation process. Since OCT enables one to obtain arbitrary plane images by manipulating the slice axis of the specimens and avoids any misinterpretation due to artifacts induced during histological preparation, our technique would be useful for examining cochlear pathologies without or prior to histological evaluations.

Taurine, Coenzyme Q10, and Hydrogen Water Prevents Germanium Dioxide-Induced Mitochondrial Dysfunction and Associated Sensorineural Hearing Loss in mouse.

Mitochondrial dysfunction has been implicated in numerous common diseases as well as aging and plays an important role in the pathogenesis of sensorineural hearing loss (SNHL). In the current study, we showed that supplementation with germanium dioxide (GeO2) in CBA/J mice resulted in SNHL due to the degeneration of the stria vascularis and spiral ganglion, which were associated with down-regulation of mitochondrial respiratory chain associated genes and up-regulation in apoptosis associated genes in the cochlea. Supplementation with taurine, coenzyme Q10, or hydrogen-rich water, attenuated the cochlear degeneration and associated SNHL induced by GeO2. These results suggest that daily supplements or consumption of antioxidants, such as taurine, coenzyme Q10, and hydrogen-rich water, may be a promising intervention to slow SNHL associated with mitochondrial dysfunction.

Application of Machine Learning to Predict Hearing Outcomes of Tympanoplasty.

OBJECTIVE: This retrospective study aimed to evaluate the performance of machine learning techniques in predicting air-bone gap after tympanoplasty compared with conventional scoring models and to identify the influential factors. METHODS: We reviewed the charts of 105 patients (114 ears) with chronic otitis media who underwent tympanoplasty. Two numerical scoring systems (middle ear risk index [MERI] and ossiculoplasty outcome parameter staging [OOPS]) and three algorithms (random forest [RF], support vector machine [SVM], and k nearest neighbor [kNN]) were created. Experimental variables included age, preoperative air-bone gap, soft-tissue density lesion in the tympanic cavity in CT, otorrhea, surgical history, ossicular bone problems in CT, tympanic perforation location, perforation type (central or marginal), grafting material, smoking history, endoscopy use, and the operator whose experience was 20 years or longer, or shorter. Binary classification, postoperative air-bone gap ≤15 or >15 dB, and multiclass classification, classification into seven categories by 10 dB, were performed, and the percentages of correct prediction were calculated. The importance of features in the RF model was calculated to identify influential factors. RESULTS: The percentages of correct prediction in binary classification were 62.3%, 72.8%, 81.5%, 81.5%, and 81.5% in MERI, OOPS, RF, SVM, and kNN, respectively, and those in multiclass classification were 29.8%, 21.9%, 63.1%, 44.7%, and 50% in the same order. The RF model suggested larger preoperative air-bone gap, and older age could make the postoperative air-bone gap larger. CONCLUSION: The machine learning techniques, especially the RF model, are promising methods for precise postoperative air-bone gap prediction. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:2371-2378, 2023.

Cholesterol granuloma in facial nerve canal presenting with facial nerve paralysis.

Cholesterol granulomas (CGs) are frequently found in the temporal bone, but their presence in the facial nerve has not been reported. We report a case of a 58-year-old woman who presented with left facial palsy caused by a CG that appeared to have originated in the facial nerve. Temporal bone computed tomography (CT) revealed soft tissue masses in the left middle ear spaces, and the facial canal was dilated from the genu to the vertical portion. Magnetic resonance imaging (MRI) revealed high signal intensity on T1-weighted images and partially high signal intensity on T2-weighted images, although no significant enhancement was observed on gadolinium-enhanced MRI. Surgical findings revealed CG in the middle ear spaces, but the facial canal remained intact and lacked continuity with the internal mass. Histopathological analysis verified the mass as a CG accompanied by cholesterol crystals. The mass was located within and continuous with the epineurium. These findings indicate that hemorrhage in the facial canal may have triggered the formation of the CG, causing left facial palsy due to increased pressure in the facial canal.

Etiology, Severity, Audiogram Type, and Device Usage in Patients with Unilateral Moderate to Profound Sensorineural Hearing Loss in Japan.

BACKGROUND: Few studies have reported on the etiology, severity, or device usage of unilateral sensorineural hearing loss (UHL) compared to bilateral hearing loss. Therefore, this study investigated the characteristics of UHL in adults and children. METHODS: We performed a survey using questionnaires for secondary and tertiary otolaryngology institutions. RESULTS: We included 15,981 patients (1549 children and 14,432 adults) from 196 institutions with otolaryngology residency programs and 2844 patients (336 children and 2508 adults) from 27 institutions with board members of the Japan Audiology Society. The latter submitted audiological data. Among children, most diagnoses were made at age 0. Approximately half of them had profound hearing loss, and 37 children (2.2%) used hearing devices. Among adults, the number of cases increased with age, but decreased when people reached their 80s and 90s. More than half of them had moderate hearing loss. Sudden sensorineural hearing loss was the most common cause of UHL of all ages; 4.4% of UHL patients used hearing devices, and most of the device users (98.6%) selected a conventional hearing aid. CONCLUSIONS: Hearing aid use is limited in children and adults with UHL in Japan. There could be many candidates with UHL for intervention such as a cochlear implant.

Short-term functional and morphological changes in guinea pig cochlea following intratympanic application of Burow's solution.

OBJECTIVES: Burow's solution, comprising aluminum sulfate and acetic acid, is an otic drug formulation applied to the tympanic cavity. We characterized the relationship between the auditory brain stem response (ABR) thresholds and the area of the capillary basement membrane anionic sites in the stria vascularis after the application of Burow's solution. METHODS: We used cationic polyethylenimine (PEI) to observe changes in the capillary basement membrane anionic sites in the stria vascularis. Burow's solution was dropped directly onto the round window membrane and retained for 2 hours. The ABRs were recorded at 4, 8, and 20 kHz immediately before surgery and before decapitation. The cochlea was extirpated immediately or 2 days after the surgery and immersed in cationic PEI solution. The PEI distribution associated with the capillary basement membrane anionic sites was measured in the basal and third turns. RESULTS: The ABR threshold shifts at 4, 8, and 20 kHz were significantly increased immediately after the surgery, whereas those at 4 and 8 kHz, but not at 20 kHz, had recovered 2 days after the surgery. Further, the PEI distribution was significantly decreased immediately after the surgery and had recovered 2 days after the surgery. CONCLUSIONS: Although Burow's solution may cause an acetic low pH in the stria vascularis and a temporary ABR threshold shift at 4 and 8 kHz, the permanent ABR threshold shift at 20 kHz cannot be attributed to the acetic low pH.

Long-Term Progression and Rapid Decline in Hearing Loss in Patients with a Point Mutation at Nucleotide 3243 of the Mitochondrial DNA.

Patients with m.3243A>G mutation of mitochondrial DNA develop bilaterally symmetric sensorineural hearing loss. However, it is unclear how fast their hearing loss progresses over time, and whether they experience rapid progression of hearing loss. In the present study, we conducted a long-term hearing evaluation in patients with MELAS or MIDD who harbored the m.3243A>G mutation of mitochondrial DNA. A retrospective chart review was performed on 15 patients with this mutation who underwent pure-tone audiometry at least once a year for more than two years. The mean follow-up period was 12.8 years. The mean progression rate of hearing loss was 5.5 dB per year. Hearing loss progressed rapidly to be profoundly deaf in seven patients during the observation period. Heteroplasmy and age-corrected heteroplasmy levels correlated with the age of onset of hearing loss. These results indicate that patients with m.3243A>G mutation have a gradual progression of hearing loss in the early stages and rapid decline in hearing to be profoundly deaf in approximately half of the patients. Although it is possible to predict the age of onset of hearing loss from heteroplasmy and age-corrected heteroplasmy levels, it is difficult to predict whether and when the rapid hearing loss will occur.

Vestibular Imaging and Function in Patients With Inner Ear Malformation Presenting With Profound Hearing Loss.

Objective: Vestibular impairment has been observed in patients with congenital hearing loss, but little is known about the vestibular anatomy and function of those in this group with inner ear malformations. This study aims to investigate the association between vestibulocochlear anatomy and vestibular function test results in children with inner ear malformations. Study Design: Case series with chart review. Setting: Pediatric patients with inner ear malformations presenting with bilateral profound hearing loss at a tertiary hospital from 1999 to 2017. Methods: Ears were classified into subgroups based on anatomic abnormalities seen on computed tomography imaging. Cervical vestibular evoked myogenic potential (cVEMP), rotatory chair, and caloric test results were obtained and collated. Descriptive and inferential statistics were calculated. Results: Of 82 ears, 29.3% had incomplete partition type II malformation, the most common type. The second-most common type was isolated vestibular organ anomaly (20.7%), which is not included in currently accepted categories. Most ears exhibited abnormal vestibular function. Abnormal vestibule volume was associated with a nonreactive cVEMP (P < .001). Radiologically abnormal lateral semicircular canals were associated with abnormal caloric and rotatory chair results (P < .001). Conclusion: With a relatively large number of cases of isolated vestibular organ anomaly not only in our study but also in previous publications, we suggest that this category be added to the subsets of inner ear malformations. Abnormal vestibule volume was significantly associated with a nonreactive cVEMP finding. The majority of patients with hearing loss secondary to inner ear malformations have abnormal vestibular function test results.

Cochlear Implantation in Patients with Mitochondrial Gene Mutation: Decline in Speech Perception in Retrospective Long-Term Follow-Up Study.

Clinical evidence of the effectiveness of cochlear implantation for hearing loss with mitochondrial DNA mutation is limited. Most reports have only described short-term postoperative speech perception, which may not reflect the limitations of cochlear implantation caused by progressive retrocochlear dysfunction. The present study aimed to investigate long-term speech perception after cochlear implantation in patients with severe to profound hearing loss associated with mitochondrial DNA mutation. A retrospective chart review was performed on patients with mitochondrial DNA mutation who had undergone cochlear implantation at the Department of Otolaryngology and Head and Neck Surgery at the University of Tokyo Hospital. We extracted data on causative mutations, clinical types, clinical course, perioperative complications, and short-term and long-term postoperative speech perception. Nine patients with mitochondrial DNA mutation underwent cochlear implantation. The mean observation period was 5.5 ± 4.2 years (range, 1-13 years), and seven patients were followed for more than 3 years. Two of the seven patients who initially showed good speech perception exhibited deterioration during long-term follow-up. The absence of an acute progression of cognitive decline in patients, showing a gradual decrease in speech perception, suggests that the deterioration of speech perception was caused by progressive retrocochlear degeneration. Although most patients with mitochondrial DNA mutation maintained good speech perception for more than 3 years after cochlear implantation, retrocochlear degeneration could cause the deterioration of speech perception during long-term follow-up.

Etiology of hearing loss affects auditory skill development and vocabulary development in pediatric cochlear implantation cases.

BACKGROUND: Cochlear implantation (CI) is an effective treatment for severe-to-profound hearing loss patients and is currently used as the standard therapeutic option worldwide. However, the outcomes of CI vary among patients. AIMS/OBJECTIVES: This study aimed to clarify the clinical features for each etiological group as well as the effects of etiology on CI outcomes. MATERIALS AND METHODS: We collected clinical information for 308 pediatric cochlear implant cases, including the etiology, hearing thresholds, age at CI, early auditory skill development, total development, monosyllable perception, speech intelligibility and vocabulary development in school age, and compared them for each etiology group. RESULTS: Among the 308 CI children registered for this survey, the most common etiology of hearing loss was genetic causes. The genetic etiology group showed the most favorable development after CI followed by the unknown etiology group, syndromic hearing loss group, congenital CMV infection group, inner ear malformation group, and cochlear nerve deficiency group. CONCLUSIONS AND SIGNIFICANCE: Our results clearly indicated that the etiology of HL affects not only early auditory skill development, but also vocabulary development in school age. The results of the present study will aid in more appropriate CI outcome assessment and in more appropriate intervention or habilitation programs.

Evaluation of the Carhart effect in congenital middle ear malformation with both an intact external ear canal and a mobile stapes footplate.

The medical charts of 41 ears with congenital middle ear malformation with both an intact external ear canal and a mobile stapes footplate were reviewed retrospectively to study the Carhart effect. The operations were categorized as successful or unsuccessful according to the extent of decrease in the average air-bone gap. Statistically significant differences were observed between the 2 groups with respect to the changes in pure-tone average and the changes in the bone conduction (BC) threshold at 1 and 2 kHz. Linear regression analysis revealed weak correlations between the change in the BC threshold and the postoperative BC threshold at an overall level and at the 4 frequencies tested. Stapes ankylosis is a main cause of the Carhart effect. The present study showed that in congenital middle ear malformation, the Carhart effect was caused not only by stapes ankylosis but also by other types of disruption in the ossicular chain.