Clinical Outcomes of Endoscopic Butterfly Inlay Cartilage Myringoplasty.

OBJECTIVE: To review a 3-year case series of endoscopic butterfly inlay cartilage myringoplasty performed by a single surgeon (W.S.K.) and analyze the clinical surgical outcomes. STUDY DESIGN: Retrospective study. SETTING: Tertiary care academic center. PATIENTS: We enrolled 60 ears with tympanic membrane (TM) perforation, receiving endoscopic inlay butterfly myringoplasty between 2019 and 2022. MAIN OUTCOMES AND MEASURES: We reviewed patients' demographics, size and location of TM perforation, operation time, complications, and postoperative pain evaluated by the numerical rating scale (NRS). We analyzed the graft uptake success rate in 5 weeks and the perforation closure rate in 4 months after surgery. We also compared the air-bone gap (ABG) before and after the surgery. RESULTS: Among the 60 ears included, the mean age was 57.0 years, and 78.3% (47 of 60) had small perforations. The average operation time was 48.9 ± 11.5 minutes, and the postoperative NRS was 2.0 ± 1.6. The immediate graft uptake success rate evaluated at postoperative 5 weeks was 96.7% (58 of 60), with myringitis occurring in three ears. Except for 11 patients lost to follow-up, the perforation closure rate evaluated at postoperative 4 months was 100% (49 of 49). The mean ABG significantly improved from preoperative status (8.87 ± 5.51 dB HL) to postoperative 4 months (6.22 ± 6.03 dB HL) (p = 0.019). CONCLUSIONS: A single surgeon's success rate for endoscopic butterfly inlay cartilage myringoplasty was almost 100%. This surgical procedure is safe and effective, with a high graft success rate.

The Role of Measuring Preoperative Social Maturation Score in Children With Additional Needs Who Underwent Cochlear Implantation.

BACKGROUND AND OBJECTIVES: Additional needs refer to specific requirements or support for individuals with disabilities or syndromes. Intellectual ability is a crucial outcome determinant of a cochlear implant. The social quotient (SQ) is an indirect predictor of intellectual capacity and social skills. This study aimed to investigate the clinical significance of the SQ on children with additional needs who received cochlear implants. Subjects and. METHODS: This study included 24 patients with diagnosed developmental delays and syndromes, who demonstrated SQ scores of <70. Preoperative social skills were evaluated using the SQ. All patients underwent cochlear implantation (CI) surgery before 7 years of age. Outcomes were evaluated using the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) and Categories of Auditory Performance (CAP) scores. Data were collected through a retrospective chart review. RESULTS: Children were categorized into three groups based on their SQ. There were no correlations between the preoperative SQ and IT-MAIS or CAP scores at 2 and 5 years of follow-up postoperatively. The CI outcomes of children with low SQ (<70) differed from those with normal development (SQ>70). In the low-SQ group, inner ear anomalies were observed in 10 (41.7%) patients. Although not statistically significant, these children exhibited a trend of lower average outcomes than children without inner ear anomalies. CONCLUSIONS: CI outcomes in children with additional needs positively affected auditory performance. Postoperative auditory and language skills tended to improve slowly in children with additional needs and a lower SQ. Over time, development gradually became more comparable to the other groups of children. However, this improvement was less than that observed in children without additional needs. Our findings support CI for children with additional needs as part of long-term auditory rehabilitation following surgery.

Enhancing Si3N4 Selectivity over SiO2 in Low-RF Power NF3-O2 Reactive Ion Etching: The Effect of NO Surface Reaction.

Highly selective etching of silicon nitride (Si3N4) and silicon dioxide (SiO2) has received considerable attention from the semiconductor community owing to its precise patterning and cost efficiency. We investigated the etching selectivity of Si3N4 and SiO2 in an NF3/O2 radio-frequency glow discharge. The etch rate linearly depended on the source and bias powers, whereas the etch selectivity was affected by the power and ratio of the gas mixture. We found that the selectivity can be controlled by lowering the power with a suitable gas ratio, which affects the surface reaction during the etching process. X-ray photoelectron spectroscopy of the Si3N4 and QMS measurements support the effect of surface reaction on the selectivity change by surface oxidation and nitrogen reduction with the increasing flow of O2. We suggest that the creation of SiOxNy bonds on the surface by NO oxidation is the key mechanism to change the etch selectivity of Si3N4 over SiO2.

Long-Term Educational and Occupational Status of Prelingually Deaf Children Who Have Received a Cochlear Implant.

OBJECTIVE: To investigate the long-term educational and occupational status of prelingually bilateral deaf children who received a cochlear implant (CI) before the age of 7, and to identify factors that influence these outcomes. STUDY DESIGN: Retrospective chart review. SETTING: Single tertiary care center. METHODS: Seventy-one children who underwent CI surgery from 2000 to 2007 were included. The latest education and occupation status and word recognition score (WRS) were analyzed. RESULTS: The mean age at the time of surgery and the current age was 3.9 and 22.4 years. The age at CI showed a negative correlation with WRS. All subjects had graduated from high school or obtained an equivalent educational qualification. General high school graduates showed a higher WRS than those who attended a special education high school. The college entrance rate of CI patients (74.6% %) was comparable to that of the general population (72.5%). Subjects who went to college had a significantly better WRS than those who did not (51.4% vs 19.3%). Excluding 30 subjects currently enrolled in college, 26 (62%) of the remaining 41 were currently employed and engaged in various vocational activities, of which most (21 out of 26, 81%) were employed through vocational training institutes, or via special recruitment policy for the disabled. CONCLUSION: The long-term use of CI in prelingually deaf children enables not only speech perception but also produces comparable levels of education and employment to those of the general population. A good WRS and supportive policy were related to these successful outcomes.

The experience of device failure after cochlear implantation.

BACKGROUND: The present study describes the treatment of patients at a tertiary institution who experienced device failure after Cochlear Implantation (CI), as well as identifying prodromic symptoms that could assist in the timely identification and management of device failure. STUDY DESIGN: Retrospective database review (January 2000-May 2017). SETTING: Single tertiary hospital. METHODS: Factors recorded included the etiology of hearing loss; age at first and revision CI surgeries; surgical information, including operation time and approach; electrical outcomes after implantation; device implanted; symptoms of device failure; history of head trauma; and audiologic outcomes as determined by categories of auditory performance (CAP). RESULTS: From January 2000 to May 2017, 1431 CIs were performed, with 27 (1.9%) undergoing revision surgeries due to device failure. The most common etiology of hearing loss was idiopathic (12/27), followed by cochlear hypoplasia (5/27). Mean age at initial CI was 11.8 (1-72) years, with 21 being pre-lingual and 6 being post-lingual. Of the total devices initially implanted, 80.5% were from Cochlear, 15.9% from MED-EL, and 3.5% from Advanced Bionics. The failure rates of these devices were 1.3%, 3.1%, and 10.0%, respectively. The most suggestive symptom of device failure was intermittent loss of signal. Mean CAP scores were 5.17 before reimplantation and 5.54 and 5.81 at 1- and 3-years, respectively, after reimplantation. CONCLUSION: The most suggestive symptom preceding device failure was intermittent loss of signal. Patients who present with this symptom should undergo electrical examination for suspected device failure. Audiologic outcomes showed continuous development despite revision surgeries.

Enhanced Operational Characteristics Attained by Applying HfO2 as Passivation in AlGaN/GaN High-Electron-Mobility Transistors: A Simulation Study.

This study investigates the operating characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying HfO2 as the passivation layer. Before analyzing HEMTs with various passivation structures, modeling parameters were derived from the measured data of fabricated HEMT with Si3N4 passivation to ensure the reliability of the simulation. Subsequently, we proposed new structures by dividing the single Si3N4 passivation into a bilayer (first and second) and applying HfO2 to the bilayer and first passivation layer only. Ultimately, we analyzed and compared the operational characteristics of the HEMTs considering the basic Si3N4, only HfO2, and HfO2/Si3N4 (hybrid) as passivation layers. The breakdown voltage of the AlGaN/GaN HEMT having only HfO2 passivation was improved by up to 19%, compared to the basic Si3N4 passivation structure, but the frequency characteristics deteriorated. In order to compensate for the degraded RF characteristics, we modified the second Si3N4 passivation thickness of the hybrid passivation structure from 150 nm to 450 nm. We confirmed that the hybrid passivation structure with 350-nm-thick second Si3N4 passivation not only improves the breakdown voltage by 15% but also secures RF performance. Consequently, Johnson's figure-of-merit, which is commonly used to judge RF performance, was improved by up to 5% compared to the basic Si3N4 passivation structure.

The rat eustachian tube: Anatomical, histological, and radiological features.

Purpose: This study investigated the anatomical and histological characteristics of the rat Eustachian tube (E-tube) and the feasibility of Eustachian tubography in a rat model. Materials and methods: Fifteen male Wistar rats were used in this study, and the bilateral E-tubes of each rat were examined. Ten E-tubes were used for anatomical studies, another ten for histological analysis, and the other ten for Eustachian tubography. Five rats were euthanized and decapitated, and ten E-tubes were dissected to describe the anatomy of the E-tube. Ten E-tube specimens obtained from five other rats were sectioned to investigate E-tube histology. Eustachian tubography was performed on the bilateral E-tubes of the other five rats using the trans-tympanic approach. Results: The rat E-tubes consisted of bony and membranous parts. Cartilage and bone tissue covered only the bony part. The E-tubes' mean diameter and overall length were 2.97 â€‹mm and 4.96 â€‹mm, respectively. The tympanic orifices' mean diameter was 1.21 â€‹mm. The epithelium of E-tubes was mainly composed of pseudostratified ciliated and goblet cells. Eustachian tubography was successfully performed on both sides of the E-tube for each rat. The technical success rate was 100%, the average running time was 4.9 â€‹min, and no procedure-related complications occurred. On tubography images, the E-tube, tympanic cavity, and nasopharynx could be identified because of the visualization of bony landmarks. Conclusion: In this study, we described the anatomical and histological features of rat E-tubes. With the aid of these findings, E-tube angiography was successfully performed using a transtympanic approach. These results will facilitate further investigation of E-tube dysfunction.

Anatomical Features of Children With Mondini Dysplasia: Influence on Cochlear Implantation Performance.

OBJECTIVE: To analyze the long-term auditory performance after cochlear implantation (CI) and identify anatomical features of Mondini dysplasia associated with post-CI outcomes. STUDY DESIGN: Retrospective study. SETTING: Tertiary care academic center. PATIENTS: We enrolled 49 ears with Mondini dysplasia who underwent CI with more than 7 years of follow-up and age at CI- and sex-matched control group with radiologically normal inner ears. MAIN OUTCOMES AND MEASURES: The development of auditory skills after CI was evaluated using word recognition scores (WRSs). The anatomical features were measured based on temporal bone computed tomography and magnetic resonance imaging, involving the width of the bony cochlear nerve canal (BCNC), cochlear basal turn, enlarged vestibular aqueduct, cochlear height, and diameter of the cochlear nerve (CN). RESULTS: CI in ears with Mondini dysplasia showed comparable benefits and improvement of auditory performance to controls during the 7 years of follow-up. In Mondini dysplasia, four (8.2%) ears showed narrow BCNC (<1.4 mm) with poorer WRS (58 ± 17%) than those with normal-sized BCNC, which had WRS (79 ± 10%) comparable to that of the control group (77 ± 14%). In Mondini dysplasia, the maximum ( r = 0.513, p < 0.001) and minimum ( r = 0.328, p = 0.021) CN diameters had positive correlations with post-CI WRS. The maximum CN diameter ( ß = 48.347, p < 0.001) and BCNC width ( ß = 12.411, p = 0.041) were significant factors that influence the post-CI WRS in multiple regression analysis. CONCLUSIONS: Preoperative anatomical evaluation, especially BCNC status and CN integrity, may serve as predictive markers for post-CI performance.

Outcomes of Endoscopic Tympanoplasty for Large Perforations: A Multicenter Retrospective Study in South Korea.

OBJECTIVES: Endoscopic tympanoplasty (ET) provides minimally invasive transcanal access to the middle ear and improves middle ear visibility for the treatment of tympanic membrane (TM) perforations. However, the literature on surgical outcomes for large TM perforations is lacking and limited to small series. This study aimed to evaluate the clinical benefits of ET for large TM perforations. METHODS: This retrospective cohort study was conducted at nine tertiary referral hospitals in South Korea, where 252 patients who underwent ET as primary surgery from September 2019 to August 2021 were included. The outcome measures included the graft success rate and pre- and postoperative audiometric data. RESULTS: In 239 patients, the graft success rate of ET for large or subtotal perforations was 86.2% (206 patients), while the graft failure rate was 13.8% (33 patients). The graft failure rate was directly correlated with surgical techniques, including overlay and medial or lateral underlay tympanoplasty (P=0.027). Lateral underlay tympanoplasty showed the most favorable. RESULTS: Sex, laterality, etiology, site and size of perforation, operation time, and graft materials did not vary significantly between the graft success and failure groups (P>0.05). The mean air-bone gap (ABG) improved significantly in both groups (graft success group: 10.0±0.6 dB and graft failure group: 7.7±0.3 dB; P<0.001). However, the ABG improvement did not significantly differ between the groups. Analysis of covariance revealed that the postoperative 500-Hz bone conduction threshold improved after successful ET (adjusted coefficient, -11.351; 95% confidence interval, -21.491 to -1.212; P=0.028). CONCLUSION: This study involved the largest population to date of large TM perforations treated by ET. The study findings suggest that ET is feasible and effective in treating large TM perforations.

Improvement in Acid Resistance of Polyimide Membranes: A Sustainable Cross-Linking Approach via Green-Solvent-Based Fenton Reaction.

In this study, we present a facile surface modification method using green solvents for a commercial polyimide (PI) nanofiltration membrane to exhibit good acid stability. To enhance acid stability, the PI organic solvent nanofiltration membrane was modified using Fenton's reaction, an oxidative cross-linking process, using environmentally friendly solvents: water and ethanol. The surface properties of the pristine and modified PI membranes were investigated and compared using various analytical tools. We studied the surface morphology using scanning electron microscopy, performed elemental analysis using X-ray photoelectron spectroscopy, investigated chemical bonds using attenuated total reflectance-Fourier transform infrared spectroscopy, and studied thermal stability using thermogravimetric analysis. The acid resistances of the pristine and modified membranes were confirmed through performance tests. The pristine PI nanofiltration membrane exposed to a 50 w/v% sulfuric acid for 4 h showed an increase in the normalized water flux to 205% and a decrease in the MgSO4 normalized rejection to 44%, revealing damage to the membrane. The membrane modified by the Fenton reaction exhibited a decline in flux and improved rejection, which are typical performance changes after surface modification. However, the Fenton-modified membrane exposed to 50 w/v% sulfuric acid for 4 h showed a flux increase of 7% and a rejection increase of 4%, indicating improved acid resistance. Furthermore, the Fenton post-treatment enhanced the thermal stability and organic solvent resistance of the PI membrane. This study shows that the acid resistance of PI membranes can be successfully improved by a novel and facile Fenton reaction using green solvents.

Outcomes of Endoscopic Congenital Cholesteatoma Removal in South Korea.

Importance: Transcanal endoscopic ear surgery (TEES) provides minimally invasive transcanal access to the middle ear and improves middle ear visibility during cholesteatoma resection. However, the literature on outcomes following TEES alone for the removal of congenital cholesteatoma (CC) is lacking and limited to small series. Objective: To assess outcomes of TEES for CC limited to the middle ear and/or mastoid antrum and to explore the risk factors associated with recidivism (ie, recurrent and/or residual cholesteatoma). Design, Setting, and Participants: This cohort study evaluated retrospective, multicenter data for 271 children with CC who underwent TEES at 9 tertiary referral hospitals in South Korea between January 1, 2013, and December 31, 2021, and had a follow-up of at least 6 months after surgery. Main Outcomes and Measures: Outcomes included the incidence of residual cholesteatoma and audiometric data after TEES. A multivariable analysis using Cox proportional hazards regression models was used to assess associations between cholesteatoma characteristics and recidivism, with hazard ratios (HRs) and 95% CIs reported. Results: Of the 271 patients (mean [SD] age, 3.5 [2.9] years; 194 [71.6%] boys, 77 [28.4%] girls), 190 had Potsic stage I CC (70.1%), 21 (7.7%) had stage II, 57 (21.0%) had stage III, and 3 (1.1%) had stage IV. Thirty-six patients (13.3%) with residual cholesteatoma were found, including 15 (7.9%) with Potsic stage I, 3 (14.3%) with stage II, and 18 (31.6%) with stage III. In the multivariable analysis, invasion of the malleus (HR, 2.257; 95% CI, 1.074-4.743) and posterosuperior quadrant location (HR, 3.078; 95% CI, 1.540-6.151) were associated with the incidence of recidivism. Overall, hearing loss (>25 dB on auditory behavioral test or >30 dB of auditory evoked responses) decreased from 24.4% to 17.7% after TEES. Conclusions and Relevance: This cohort study involved the largest known population to date of CC removed by TEES. The findings suggest that TEES may be feasible and effective for the removal of CC limited to the middle ear and/or mastoid antrum in children.

Optimization of Gate-Head-Top/Bottom Lengths of AlGaN/GaN High-Electron-Mobility Transistors with a Gate-Recessed Structure for High-Power Operations: A Simulation Study.

In this study, we propose an optimized AlGaN/GaN high-electron-mobility transistor (HEMT) with a considerably improved breakdown voltage. First, we matched the simulated data obtained from a basic T-gate HEMT with the measured data obtained from the fabricated device to ensure the reliability of the simulation. Thereafter, to improve the breakdown voltage, we suggested applying a gate-head extended structure. The gate-head-top and gate-head-bottom lengths of the basic T-gate HEMT were symmetrically extended by 0.2 µm steps up to 1.0 µm. The breakdown voltage of the 1.0 µm extended structure was 52% higher than that of the basic T-gate HEMT. However, the cutoff frequency (fT) and maximum frequency (fmax) degraded. To minimize the degradation of fT and fmax, we additionally introduced a gate-recessed structure to the 1.0 µm gate-head extended HEMT. The thickness of the 25 nm AlGaN barrier layer was thinned down to 13 nm in 3 nm steps, and the highest fT and fmax were obtained at a 6 nm recessed structure. The fT and fmax of the gate-recessed structure improved by 9% and 28%, respectively, with respect to those of the non-gate-recessed structure, and further improvement of the breakdown voltage by 35% was observed. Consequently, considering the trade-off relationship between the DC and RF characteristics, the 1.0 µm gate-head extended HEMT with the 6 nm gate-recessed structure was found to be the optimized AlGaN/GaN HEMT for high-power operations.

Tapered self-expandable metallic stent optimized for Eustachian tube morphology in a porcine ET model.

Several investigations on the feasibility of stent placement into the Eustachian tube (ET) are being conducted. However, stents optimized for the anatomical structure of the ET have not yet been developed. In this study, the efficacy and safety of a self-expandable metallic stent (SEMS) optimized for porcine ET morphology was investigated. Silicone was injected into a cadaveric porcine ET to analyze the ET morphology. The three-dimensional-reconstructed porcine ET phantom images obtained after a computed tomography scan were measured to determine the dimensions of the porcine ET. The SEMS was designed as a tapered structure on the basis of the morphological findings of the porcine ET. The tapered SEMS (T-SEMS) and conventional SEMS (C-SEMS) were placed into the porcine ET to compare the safety and efficacy of the two types of SEMSs. Stent-induced tissue hyperplasia in the T-SEMS group was significantly lower than that in the C-SEMS group (p < 0.001). The T-SEMS optimized for the porcine ET was effective in maintaining stent patency. T-SEMS seems to be better than C-SEMS in suppressing stent-induced tissue hyperplasia, owing to the reduced stent-mediated mechanical injuries and maintaining ET patency.

Analysis of Operational Characteristics of AlGaN/GaN High-Electron-Mobility Transistor with Various Slant-Gate-Based Structures: A Simulation Study.

This study investigates the operational characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying a slant-gate structure and drain-side extended field-plate (FP) for improved breakdown voltage. Prior to the analysis of slant-gate-based HEMT, simulation parameters were extracted from the measured data of fabricated basic T-gate HEMTs to secure the reliability of the results. We suggest three different types of slant-gate structures that connect the basic T-gate electrode boundary to the 1st and 2nd SiN passivation layers obliquely. To consider both the breakdown voltage and frequency characteristics, the DC and RF characteristics of various slant-gate structures including the self-heating effect were analyzed by TCAD simulation. We then applied a drain-side extended FP to further increase the breakdown voltage. The maximum breakdown voltage was achieved at the FP length of 0.4 µm. Finally, we conclude that the slant-gate structures can improve breakdown voltage by up to 66% without compromising the frequency characteristics of the HEMT. When the drain-side FP is applied to a slant-gate structure, the breakdown voltage is further improved by up to 108%, but the frequency characteristics deteriorate. Therefore, AlGaN/GaN HEMTs with an optimized slant-gate-based structure can ultimately be a promising candidate for high-power and high-frequency applications.

The first progress of plasma-based transition metal dichalcogenide synthesis: a stable 1T phase and promising applications.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted attention as polymorphs depending on their phases (1T and 2H) when applying typical synthesis methods. The 2H phase is generally synthesised through chemical vapour deposition (CVD) on a wafer-scale at high temperatures, and many synthesis methods have been reported owing to their thermodynamic stability and semiconductor properties. By contrast, although the 1T phase is meta-stable with an octahedral coordination, thereby limiting the use of synthesis methods, the recent structural advantage in terms of the hydrogen evolution reaction (HER) has been emphasised. Despite this demand, no large-area thin-film synthesis method for 1T-TMDs has been developed. Among several strategies of synthesizing metallic-phase (1T) TMDs, chemical exfoliation (alkali metal intercalation) is a major strategy and others have been used for electron-beam irradiation, laser irradiation, defects, plasma hot electron transfer, and mechanical strain. Therefore, we suggest an innovative synthesis method using plasma-enhanced CVD (PECVD) for both the 1T and 2H phases of TMDs (MoS2 and WS2). Because ions and radicals are accelerated to the substrate within the sheath region, a high-temperature source is not needed for vapour ionisation, and thus the process temperature can be significantly lowered (150 °C). Moreover, a 4-inch wafer-scale of a thin film is an advantage and can be synthesised on arbitrary substrates (SiO2/Si wafer, glassy carbon electrode, Teflon, and polyimide). Furthermore, the PECVD method was applied to TMD-graphene heterostructure films with a graphene-transferred substrate, and for the first time, sequential metal seed layer depositions of W (1 nm) and Mo (1 nm) were sulfurized to MoS2-WS2 vertical heterostructures with Ar + H2S plasma. We considered the prospects and challenges of the new PECVD method in the development of practical applications in next-generation integrated electronics, HER catalysts, and flexible biosensors.

Long-term Changes of Hearing Thresholds and Eustachian Tube Function After Balloon Dilation of the Eustachian Tube in Patients With Chronic Otitis Media.

OBJECTIVES: This study aimed to evaluate long-term changes after balloon dilation of the Eustachian tube (BDET) in chronic otitis media (COM) patients with Eustachian tube (ET) dysfunction that persisted after tympanomastoidectomy (TM). METHODS: We retrospectively reviewed the medical records of consecutive patients who were diagnosed with COM and ET dysfunction and underwent TM at our tertiary hospital from 2016 to 2017. The tympanic membrane status, the presence of a ventilation tube, ability to perform the Valsalva maneuver, and audiologic changes after dilation of the ET were analyzed. RESULTS: This study included 20 patients (with 21 ears) who underwent TM but could not perform the Valsalva maneuver, showed a persistent air-bone gap, and eventually underwent BDET (male:female, 8:13; right:left, 11:10). Four ears showed perforation of the tympanic membrane after TM. Among the remaining 17 ears, 15 ears underwent ventilation tube insertion before BDET, while two ears underwent ventilation tube insertion and BDET simultaneously. Although none of the patients were capable of the Valsalva maneuver before BDET, 13 (62%) were able to perform the Valsalva maneuver successfully after BDET. When evaluating the tympanic membrane status at the latest follow-up, ventilation tubes were still present in eight ears. In the other 13 ears, intact tympanic membranes were present in nine out of 11 ears n the successful Valsalva group, whereas none of them were intact in the unsuccessful Valsalva group (P=0.014). The successful Valsalva group after BDET showed an improved air-bone gap of 8.9±12.4 dB, while the unsuccessful Valsalva group showed an aggravated air-bone gap of 3.8±11.8 dB at 1 year after BDET; this difference was statistically significant (P=0.031). CONCLUSION: The Valsalva maneuver could be performed successfully after BDET by 62% of patients with COM and ET dysfunction. BDET is helpful for successful hearing improvement and improved tympanic aeration in COM patients with ET dysfunction.

Endoscopic Ear Surgery for Congenital Cholesteatoma in Children.

BACKGROUND: Endoscopic ear surgery is a promising technique for removing congenital cholesteatoma in children. It can provide greater visual access to hidden areas of the middle ear and facilitate middle-ear manipulation. This study compares a single-center experience in manag- ing congenital cholesteatoma with an endoscopic approach with that in managing congenital cholesteatoma with a conventional microscopic approach. METHODS: Records of consecutive patients aged under 8 with congenital cholesteatoma confined to the middle ear at our tertiary referral hospital from January 2013 to December 2018 were retrospectively reviewed. Operation time, hospital stay, postoperative complications, and recurrence/residue of congenital cholesteatoma were compared between patients receiving microscopic versus endoscopic surgery. RESULTS: A total of 33 pediatric patients aged from 19 months to 7 years were enrolled; 12 children underwent microscopic surgery, and 21 received an endoscopic approach for removing congenital cholesteatoma. The mean operative time was 1.61 hours for the microscopic group and 1.49 hours for the endoscopic group without statistical difference. No postoperative sensorineural hearing loss and complications were reported. Four cases of recurrence/residue were observed on the follow-up endoscopic exam or computed tomography, and no differences were shown between the 2 groups. Of the total patients, 94.7% (n=11) in the microscopic group and 90.5% (n=19) in the endoscopic group demonstrated an intact tympanic membrane without perforation or retraction after surgery. No audiological differences were reported between the 2 groups. CONCLUSION: Endoscopic ear surgery can effectively and safely remove congenital cholesteatoma in children and is not inferior to conventional microscopic approaches.

Serial histological changes in the cartilaginous eustachian tube in the rat following balloon dilation.

Although balloon dilation has shown promising results in the treatment of dilatory Eustachian tube (ET) dysfunction, the histological effects of ET balloon dilation (ETBD) is unknown because histological examination of the whole human cartilaginous ET is impossible. Animal studies are needed to elucidate the effect of ETBD so we evaluated the histological changes after ETBD in a rat model. The left ET of 20 Wistar rats was dilated with a balloon catheter and the right ET was used as a control. Five rats were sacrificed immediately after ETBD, at 1, 4 and 12 weeks after the procedure for histological examination. The epithelial cells, presence of epithelial hyperplasia, and the proportion of the goblet cells in the epithelium; the vascular structures and dimensions of the submucosa; and presence of cartilage fracture and the area of the ET lumen were evaluated and compared between the groups. Desquamation of nearly all epithelial cells and the fracture of tubal cartilages were observed immediately after ETBD. At 1-week post-ETBD, the ciliated epithelial cells started to recover with epithelial hyperplasia. The goblet cells recovered by 4 weeks post-ETBD and epithelial hyperplasia decreased but was still present at 12 weeks post-ETBD. The depth of the submucosa increased and neovascularization in this region was observed at 1-week post-ETBD and persisted up to 12 weeks post-ETBD. The lumen of the cartilaginous ET increased immediately after ETBD but decreased at 1-week post-ETBD. The cartilaginous ET lumen recovered to the normal value at 4 weeks post-ETBD. This study is the first to describe the serial histological changes to the cartilaginous ET after ETBD and helps our understanding of the histological changes that occur after an ETBD intervention for intractable ET dysfunction.

Sirolimus-eluting cobalt-chrome alloy stent suppresses stent-induced tissue hyperplasia in a porcine Eustachian tube model.

Various preclinical studies with developed Eustachian tube (ET) stents are in progress but have not yet been clinically applied. ET stent is limited by stent-induced tissue hyperplasia in preclinical studies. The effectiveness of sirolimus-eluting cobalt-chrome alloy stent (SES) in suppressing stent-induced tissue hyperplasia after stent placement in the porcine ET model was investigated. Six pigs were divided into two groups (i.e., the control and the SES groups) with three pigs for each group. The control group received an uncoated cobalt-chrome alloy stent (n = 6), and the SES group received a sirolimus-eluting cobalt-chrome alloy stent (n = 6). All groups were sacrificed 4 weeks after stent placement. Stent placement was successful in all ETs without procedure-related complications. None of the stents was able to keep its round shape as original, and mucus accumulation was observed inside and around the stent in both groups. On histologic analysis, the tissue hyperplasia area and the thickness of submucosal fibrosis were significantly lower in the SES group than in the control group. SES seems to be effective in suppressing stent-induced tissue hyperplasia in porcine ET. However, further investigation was required to verify the optimal stent materials and antiproliferative drugs.

Diagnostic Validity of Auditory Brainstem Response for the Initial Screening of Vestibular Schwannoma.

BACKGROUND AND OBJECTIVES: To investigate the diagnostic validity of auditory brainstem response (ABR) in the screening of vestibular schwannoma (VS). SUBJECTS AND METHODS: Forty patients diagnosed with VS using magnetic resonance imaging who had undergone ABR before treatment between 2005 and 2015 were included. ABR results were considered positive when findings met at least one of the following criteria: 1) absent evoked response, 2) desynchronization of waves other than wave I, 3) interpeak latency (IPL) between waves I and III >2.5 ms, 4) IPL between waves I and V >4.4 ms, 5) wave V interaural latency difference >0.2 ms, and 6) interaural difference in IPL between waves I and V >0.2 ms. RESULTS: The overall sensitivity of ABR was 85.0%. For tumors measuring <10 mm, the sensitivity of ABR was 66.7%, whereas it increased to 90.3% for tumors measuring >10 mm. The sensitivity of tumors confined to the internal acoustic canal was 73.3% compared with 100.0% for tumors confined to the cerebellopontine angle. In patients with serviceable hearing, the mean tumor size was 7.8±2.9 mm in patients with a normal ABR and 15.1±9.4 mm in patients with an abnormal ABR, indicating a significant difference (p<0.05). CONCLUSIONS: ABR alone is insufficient for the screening of VS, bearing the risk of false-negative outcomes when examining small, intracanalicular tumors. However, ABR can be inexpensively applied for the screening of VS measuring >10 mm in patients with serviceable hearing, supporting the need for further active diagnostic and treatment modalities in clinical practice.