The role of SLC26A4 in bony labyrinth development and otoconial mineralization in mouse models.

Inner ear malformations are predominantly attributed to developmental arrest during the embryonic stage of membranous labyrinth development. Due to the inherent difficulty in clinically assessing the status of the membranous labyrinth, these malformations are diagnosed with radiographic imaging, based on the morphological characteristics of the bony labyrinth. While extensive research has elucidated the intricacies of membranous labyrinth development in mouse models, comprehensive investigations into the developmental trajectory of the bony labyrinth, especially about its calcification process, have been notably lacking. One of the most prominent types of inner ear malformations is known as incomplete partition (IP), characterized by nearly normal external cochlear appearance but pronounced irregularities in the morphology of the modiolus and inter-scalar septa. IP type II (IP-II), also known as Mondini dysplasia, is generally accompanied by an enlargement of the vestibular aqueduct and is primarily attributed to mutations in the SLC26A4 gene. In the case of IP-II, the modiolus and inter-scalar septa of the cochlear apex are underdeveloped or missing, resulting in the manifestation of a cystic structure on radiographic imaging. In this overview, we not only explore the normal development of the bony labyrinth in mice but also present our observations on otolith mineralization. Furthermore, we investigated the specifics of bony labyrinth and otolith mineralization in Slc26a4-deficient mice, which served as an animal model for IP-II. We ensured that these findings promise to provide valuable insights for the establishment of therapeutic interventions, optimal timing, targeted sites, and preventive measures when considering the management of this condition.

Detailed Clinical Features of PTPRQ-Associated Hearing Loss Identified in a Large Japanese Hearing Loss Cohort.

The PTPRQ gene has been identified as one of the genes responsible for non-syndromic sensorineural hearing loss (SNHL), and assigned as DFNA73 and DFNB84. To date, about 30 causative PTPRQ variants have been reported to cause SNHL. However, the detailed clinical features of PTPRQ-associated hearing loss (HL) remain unclear. In this study, 15,684 patients with SNHL were enrolled and genetic analysis was performed using massively parallel DNA sequencing (MPS) for 63 target deafness genes. We identified 17 possibly disease-causing PTPRQ variants in 13 Japanese patients, with 15 of the 17 variants regarded as novel. The majority of variants identified in this study were loss of function. Patients with PTPRQ-associated HL mostly showed congenital or childhood onset. Their hearing levels at high frequency deteriorated earlier than that at low frequency. The severity of HL progressed from moderate to severe or profound HL. Five patients with profound or severe HL received cochlear implantation, and the postoperative sound field threshold levels and discrimination scores were favorable. These findings will contribute to a greater understanding of the clinical features of PTPRQ-associated HL and may be relevant in clinical practice.

Combined genetic polymorphisms of the GSTT1 and NRF2 genes increase susceptibility to cisplatin-induced ototoxicity: A preliminary study.

OBJECTIVE: The genotype-phenotype relationship in cisplatin-induced ototoxicity remains unclear. By assessing early shifts in distortion product otoacoustic emission (DPOAE) levels after initial cisplatin administration, we aimed to discriminate patients' susceptibility to cisplatin-induced ototoxicity and elucidate their genetic background. STUDY DESIGN: A prospective cross-sectional study. SETTING: Tertiary referral hospital in Japan. PATIENTS: Twenty-six patients with head and neck cancer were undergoing chemoradiotherapy with three cycles of 100 mg/m2 cisplatin. INTERVENTIONS: Repetitive pure-tone audiometry and DPOAE measurements, and blood sampling for DNA extraction were performed. Patients were grouped into early ototoxicity presence or absence based on whether DPOAE level shifts exceeded the corresponding reference limits of the 21-day test interval. MAIN OUTCOME MEASURES: Hearing thresholds after each cisplatin cycle, severity of other adverse events, and polymorphisms in cisplatin-induced ototoxicity-associated genes were compared. RESULTS: Early ototoxicity was present in 14 and absent in 12 patients. Ototoxicity presence on DPOAEs was associated with greater progression of hearing loss in frequencies ≥2 kHz throughout therapy and with higher ototoxicity grades compared with ototoxicity absence. Ototoxicity was further associated with grade ≥2 nausea. Ototoxicity presence was genetically associated with the GSTT1 null genotype and G-allele of NFE2L2 rs6721961, whereas ototoxicity absence was associated with the GSTM1 null genotype. Dose-dependent progression of hearing loss was the greatest in the combined genotype pattern of GSTT1 null and the T/G or G/G variants of rs6721961. CONCLUSION: Early DPOAE changes reflected genetic vulnerability to cisplatin-induced ototoxicity. Hereditary insufficiency of the antioxidant defense system causes severe cisplatin-induced hearing loss and nausea.

High fluence in laser stapedotomy aggravates transient subjective dizziness.

BACKGROUND: Laser fenestration in stapedotomy has thermal effect to the vestibule. AIMS/OBJECTIVES: To evaluate the role of energy density (fluence) in the severity of postoperative vestibular symptoms. MATERIALS AND METHODS: The retrospective chart-review study included 84 patients with otosclerosis that underwent primary laser stapedotomy. Surgical outcomes, including nystagmus, and subjective vestibular symptoms during one-month follow-up, were compared between potassium titanyl phosphate (KTP) and CO2 laser. According to this study and literature, we assessed the relationship between laser parameters and the incidence of persistent vestibular symptoms lasting more than one week after surgery. RESULTS: The KTP and CO2 laser group included 48 and 36 patients, respectively. Fluence was different between the KTP (637 J/cm2) and CO2 (141 J/cm2) laser (p < .001). The KTP group showed gradual decrease in dizziness during one-month observation period, while the CO2 group exhibited a steep recovery curve in the first postoperative week (9 and 4 d of duration, respectively). The incidence of persistent vestibular symptoms was correlated with both fluence (r = 0.80, p = .01) and spot size (r = -0.74, p = .01). CONCLUSIONS AND SIGNIFICANCE: Appropriate setting of parameters with lower fluence is desirable for the efficiency and safety of laser stapedotomy.Abbreviations: ABG: air-bone gap; SD: standard deviation.

Three-dimensionally visualized ossification and mineralization process of the otic capsule in a postnatal developmental mouse.

Objective: We aimed to elucidate the ossification process of the otic capsule in postnatal C57BL/6 mice and depict the three-dimensional (3D) process of otoconial mineralization in vivo. Methods: The otic capsules of C57BL/6 mice were stained with alizarin red and imaged/compared using micro-computed tomography on postnatal day (P) between P0 and P8, P10, P15, and P30 and 3-4 months old (P3-4Mo). We reconstructed 3D images of the otic capsule and otoconia and measured the bone mineral density using x-ray absorptiometry on each age. Results: The 3D reconstructed otic capsule images revealed two ossification centers of the otic capsule at P0. One was observed around the ampulla of the superior semicircular canal and utricle, and the other was observed around the ampulla of the posterior semicircular canal. The cross-sectional views demonstrated that modiolar ossification developed from the base to the apex from P4 to P8. The inter-scalar septum ossified bidirectionally from the modiolus and bony otic capsule from P8 to P15. The mineralized otoconia were first detected in the utricle at P3 and saccular otoconia at P6. The density of the utricle and saccular otoconia showed different growth trends. Conclusion: To the best of our knowledge, this is the first study to demonstrate the 3D appearance of the otic capsule and otoconia in different developmental stages of mice. We also revealed that modiolar and inter-scalar septal calcification is the final event in the cochlea and that it can be susceptible to pathological conditions (cochlear congenital malformations and hereditary vestibular diseases). The unique features of the ossification process and duration may explain these pathological conditions observed in humans. Level of Evidence: 3.

Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss.

OBJECTIVE: To compare the findings of magnetic resonance imaging (MRI) with advanced protocols in patients with various types of acute sensorineural hearing loss (ASNHL). STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Two hundred eighty-seven patients with ASNHL. INTERVENTIONS: All patients underwent MRI scanning, including heavily T2-weighted three-dimensional fluid-attenuated inversion recovery before and 4 hours after the intravenous administration of gadolinium contrast medium (delayed 3D-FLAIR). A hybrid of the reversed image of the positive endolymph signal and the native image of the perilymph signal image was constructed to visualize the endolymphatic space. RESULTS: The detection rates of abnormal MRI findings vary significantly among different types of ASNHL. A hyperintense signal on delayed 3D-FLAIR was observed in all patients with intralabyrinthine schwannoma or vestibular schwannoma and 20.5% of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) but was rarely observed in definite Ménière's disease (MD, 2.6%). In contrast, endolymphatic hydrops (EH) was frequently observed in patients with definite MD (79.5%) but was observed much less frequently in patients with ISSNHL (11.0%). In patients with cochlear MD and ALHL, detection rates of cochlear EH were similar to those with definite MD, whereas detection rates of vestibular EH were significantly lower than in patients with definite MD. CONCLUSIONS: The significantly different detection rates of abnormal MRI findings among various types of ASNHL shed light on the distinct pathophysiology of each disorder. A diagnosis based on MRI findings with advanced protocols may help select treatment strategies and provide prognostic information for patients.

Quantitative analysis and correlative evaluation of video-oculography, micro-computed tomography, and histopathology in Pendrin-null mice.

Patients with SLC26A4 mutations exhibit highly variable hearing loss and vestibular dysfunction. Although Slc26a4 mutant mice similarly exhibit vestibular deficits, including circling behavior, head tilting, and torticollis, the underlying pathogenesis of the vestibular symptoms remains unclear, hindering its effective management for patients with SLC26A4 mutations. In this study, we evaluated the equilibrium function using the inspection equipment, which can record eye movements against rotational, gravitational, and thermal stimulations. Moreover, we correlated the degree of functional impairment with the morphological alterations observed in Slc26a4Δ/Δ mice. The rotational stimulus and ice water caloric tests revealed considerable impairment of the semicircular canal, while the tilted gravitational stimulus test showed a severe functional decline of the otolithic system in Slc26a4Δ/Δ mice. Generally, the degree of impairment was more severe in circling Slc26a4Δ/Δ mice than in non-circling Slc26a4Δ/Δ mice. In non-circling Slc26a4Δ/Δ mice, the semicircular canal function was normal. Micro-computed tomography results showed enlargement of the vestibular aqueduct and bony semicircular canals but no correlative relationship between the severity of the caloric response and the size of bony labyrinths. Giant otoconia and a significant decrease in total otolith volume in the saccule and utricle were observed in Slc26a4Δ/Δ mice. However, the giant otoconia were not overly dislocated in the bony otolithic system and ectopic otoconia were absent in the semicircular canal. The number and morphology of the utricular hair cells in Slc26a4Δ/Δ mice were not significantly reduced compared to those in Slc26a4Δ/+ mice. Collectively, we can conclude that vestibular impairments are mainly associated with otoconia formation and morphology rather than hair cell degeneration. In addition, severe disturbances of semicircular canals cause circling behavior in Slc26a4Δ/Δ mice. Our comprehensive morphological and functional assessments apply to mouse models of other genetic diseases with vestibular impairment.

Cholesteatoma has an altered microbiota with a higher abundance of Staphylococcus species.

Objective: To compare the microbiota between cholesteatoma and chronic suppurative otitis media (COM) and to identify potential pathogens that explain the relevant phenotypes of cholesteatoma. Study Design: Prospective cohort study. Methods: Surgical specimens collected from 20 cholesteatomas and nine COMs were treated to dissolve biofilms and subjected to 16S ribosomal RNA (rRNA) gene sequencing and amplicon sequence variant-level analysis for microbiota profiling and quantitative comparison. Correlations between the relative abundance of potential pathogens and the volume of the primary resected cholesteatomas were examined. Results: Differences in bacterial composition (beta diversity) were observed between cholesteatomas and COM (p = .002), with a higher abundance of Staphylococcus in cholesteatomas than in COM (p = .005). Common genera in the external auditory canal (EAC) flora, such as Staphylococcus, Corynebacterium, and Cutibacterium, were predominant in both cholesteatoma and COM; Staphylococcus aureus and Pseudomonas aeruginosa were increased in both diseases compared with the EAC flora. Furthermore, coagulase-negative staphylococci (CoNS) were more abundant in cholesteatomas than in COM (p = 0.002). Linear discriminant analysis coupled with effect size measurements (LEfSe) identified four CoNS as potential biomarkers for cholesteatoma. The relative abundance of S. aureus, a potential pathogen, was positively correlated with cholesteatoma volume (r = .60, p = .02). Conclusion: The microbiota of cholesteatoma and COM originated from EAC flora, but the bacterial composition was largely altered. Our results suggested that S. aureus infection is involved in cholesteatoma progression. Level of Evidence: 3b.

Tissue-Resident Macrophages in the Stria Vascularis.

Tissue-resident macrophages play an important role in clearance, development, and regulation of metabolism. They also function as sentinel immune cells, initiating inflammatory responses, clearing inflammatory debris, and maintaining homeostatic tissue environment. In the cochlea, the roles of tissue-resident macrophages include maintaining steady-state tissues, immunological defense, and repairing pathological conditions associated with noise, ototoxic drugs, aging, and various pathogens. Perivascular macrophages (PVMs) are a unique subset of tissue-resident macrophages that are closely associated with blood vessels and have unique expression markers in certain tissues. PVMs are found in the inner ear, brain, skin, liver, and retina. The origin of PVMs in the inner ear is unclear, but they are already present during embryonic development. PVMs are members of the blood labyrinth barrier and regulate blood vessel permeability in the stria vascularis, which lies on the lateral wall of the cochlear duct and is crucial for endocochlear potential formation. The cytoplasm of strial PVMs can contain pigment granules that increase in number with age. Strial PVMs are activated by the loss of Slc26a4 in the cochleae, and they subsequently phagocytose aggregated pigment granules and possibly degenerated intermediate cells. This review summarizes the current knowledge of characteristic features and proposed roles of PVMs in the stria vascularis. We also address macrophage activation and involvement of pigment granules with the loss of Slc26a4 in the cochleae.

Prediction of postoperative visual acuity after vitrectomy for macular hole using deep learning-based artificial intelligence.

PURPOSE: To create a model for prediction of postoperative visual acuity (VA) after vitrectomy for macular hole (MH) treatment using preoperative optical coherence tomography (OCT) images, using deep learning (DL)-based artificial intelligence. METHODS: This was a retrospective single-center study. We evaluated 259 eyes that underwent vitrectomy for MHs. We divided the eyes into four groups, based on their 6-month postoperative Snellen VA values: (A) ≥ 20/20; (B) 20/25-20/32; (C) 20/32-20/63; and (D) ≤ 20/100. Training data were randomly selected, comprising 20 eyes in each group. Test data were also randomly selected, comprising 52 total eyes in the same proportions as those of each group in the total database. Preoperative OCT images with corresponding postoperative VA values were used to train the original DL network. The final prediction of postoperative VA was subjected to regression analysis based on inferences made with DL network output. We created a model for predicting postoperative VA from preoperative VA, MH size, and age using multivariate linear regression. Precision values were determined, and correlation coefficients between predicted and actual postoperative VA values were calculated in two models. RESULTS: The DL and multivariate models had precision values of 46% and 40%, respectively. The predicted postoperative VA values on the basis of DL and on preoperative VA and MH size were correlated with actual postoperative VA at 6 months postoperatively (P < .0001 and P < .0001, r = .62 and r = .55, respectively). CONCLUSION: Postoperative VA after MH treatment could be predicted via DL using preoperative OCT images with greater accuracy than multivariate linear regression using preoperative VA, MH size, and age.

Application of a virtual and mixed reality-navigation system using commercially available devices to the lateral temporal bone resection.

BACKGROUND: Lateral temporal bone resection (LTBR) is performed for stage T1-2 external ear malignant tumors and requires spatial anatomical knowledge of the rare surgical field. OBJECTIVE: This paper presents a novel virtual reality (VR) based surgical simulation and navigation system using only commercially available display device and an online software, to assist in the understanding of the anatomy pre and intraoperatively. RESULT AND CONCLUSION: VR model created by 3D Slicer modules and visualized on head mounted display enabled users to simulate and learn surgical techniques of a rare surgical case. 3D hologram through HoloLens assisted the surgeon in comprehending the spatial relationship between crucial vital structures and the pathological lesion during the operation. This platform does not require the users to possess specific programming skill or knowledge, and is therefore applicable in daily clinical usage.

Cochlear Pathomorphogenesis of Incomplete Partition Type II in Slc26a4-Null Mice.

Incomplete partition type II (IP-II) is frequently identified in ears with SLC26A4 mutations. Cochleae with IP-II are generally observed to have 1½ turns; the basal turns are normally formed, and the apical turn is dilated or cystic. The objective of this study was to characterize the pathomorphogenesis of the IP-II cochlear anomaly in Slc26a4-null mice. Otic capsules were dissected from Slc26a4Δ/+ and Slc26a4Δ/Δ mice at 1 and 8 days of age and at 1 and 3 months of age. X-ray micro-computed tomography was used to image samples. We used a multiplanar view and three-dimensional reconstructed models to calculate the cochlear duct length, cochlear turn rotation angle, and modiolus tilt angle. The number of inner hair cells was counted, and the length of the cochlear duct was measured in a whole-mount preparation of the membranous labyrinth. X-ray micro-computed tomography mid-modiolar planar views demonstrated cystic apical turns in Slc26a4Δ/Δ mice resulting from the loss or deossification of the interscalar septum, which morphologically resembles IP-II in humans. Planes vertical to the modiolus showed a similar mean rotation angle between Slc26a4Δ/+ and Slc26a4Δ/Δ mice. In contrast, the mean cochlear duct length and mean number of inner hair cells in Slc26a4Δ/Δ mice were significantly smaller than in Slc26a4Δ/+ mice. In addition, there were significant differences in the mean tilt angle and mean width of the modiolus. Our analysis of Slc26a4-null mice suggests that IP-II in humans reflects loss or deossification of the interscalar septum but not a decreased number of cochlear turns.

Four-Hour Delayed Gadolinium-Enhanced 3D-FLAIR MR Imaging Highlights Intralabyrinthine Micro-Schwannomas.

OBJECTIVE: To demonstrate the clinical significance of 4-hour delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery (delayed 3D-FLAIR) in patients with intralabyrinthine schwannoma (ILS). PATIENTS: Three patients who were clinically diagnosed with ILS. INTERVENTIONS: All patients underwent audiological examinations and magnetic resonance imaging (MRI) scans. The MR-protocol included axial MR cisternography, immediate gadolinium-enhanced T1-weighted sequence, and heavily T2-weighted 3D-FLAIR prior to and 4 hours after the intravenous administration of gadolinium contrast medium. MAIN OUTCOME MEASURES: All MR images were visually inspected. RESULTS: In all three patients with ILS, delayed 3D-FLAIR MRI demonstrated a strong signal of cochlear fluid surrounding the tumor, which highlighted a tumor region that lacked signals. CONCLUSIONS: Delayed 3D-FLAIR MRI may serve as a novel diagnostic tool for the early detection of intralabyrinthine micro-schwannoma. The findings also shed light on the pathophysiology of ILS.

Cyclotron production of 225Ac from an electroplated 226Ra target.

PURPOSE: We demonstrate cyclotron production of high-quality 225Ac using an electroplated 226Ra target. METHODS: 226Ra was extracted from legacy Ra sources using a chelating resin. Subsequent ion-exchange purification gave pure 226Ra with a certain amount of carrier Ba. The radium target was prepared by electroplating. We successfully deposited about 37 MBq of 226Ra on a target box. Maximum activation was achieved using 15.6 MeV protons on the target at 20 µA for 5 h. Two functional resins with various concentrations of nitric acid purified 225Ac and recovered 226Ra. Cooling the intermediate 225Ac for 2-3 weeks decayed the major byproduct of 226Ac and increased the radionuclidic purity of 225Ac. Repeating the same separation protocol provided high-quality 225Ac. RESULTS: We obtained 225Ac at a yield of about 2.4 MBq at the end of bombardment (EOB), and the subsequent initial purification gave 1.7 MBq of 225Ac with 226Ac/225Ac ratio of < 3% at 4 days from EOB. Additional cooling time coupled with the separation procedure (secondary purification) effectively increased the 225Ac (4n + 1 series) radionuclidic purity up to 99 + %. The recovered 225Ac had a similar identification to commercially available 225Ac originating from a 229Th/225Ac generator. CONCLUSION: This procedure, which involves the 226Ra(p,2n)225Ac reaction and the appropriate purification, has the potential to be a major alternative pathway for 225Ac production because it can be performed in any facility with a compact cyclotron to address the increasing demand for 225Ac.

Patient-specific virtual and mixed reality for immersive, experiential anatomy education and for surgical planning in temporal bone surgery.

OBJECTIVE: The recent development of extended reality technology has attracted interest in medicine. We explored the use of patient-specific virtual reality (VR) and mixed reality (MR) temporal bone models in anatomical teaching, pre-operative surgical planning and intra-operative surgical referencing. METHODS: VR and MR temporal bone models were created and visualized on head-mounted display (HMD) and MR headset respectively, by a novel webservice that allows users to convert computed tomography images to VR and MR images without specific knowledge of programming. Eleven otorhinolaryngology trainees and specialists were asked to manipulate the healthy VR temporal bone model and to assess its validity by filling out a questionnaire. Additionally, VR and MR pathological models of petrous apex cholesteatoma were utilized for surgical planning pre-operatively and for referring to the anatomy during the surgery. RESULTS: Most participants were favorable about the VR model and considered HMD as superior to a flat computer screen. 91% of the participants agreed or somewhat agreed that VR through HMD is cost effective. In addition, the VR pathological model was used for planning and sharing the surgical approach during a pre-operative surgical conference. The MR headset was worn intra-operatively to clarify the relationship between the pathological lesion and vital anatomical structures. CONCLUSION: Regardless of the participants' training level in otorhinolaryngology or VR experience, all participants agreed that the VR temporal bone model is useful for anatomical education. Furthermore, the creation of patient-specific VR and MR models using the webservice and their pre- and intra-operative usages indicated the potential of innovative adjunctive surgical instrument.

[Factors associated with behaviors to prevent COVID-19 infection during the declaration of emergency: A study among Tokyo residents].

Objectives　The COVID-19 pandemic spread rapidly across the globe during the first half of 2020. In Japan, a state of emergency was declared on April 7, 2020, which had a significant impact on the life of citizens. This study focused on behaviors like avoiding going out or coming in contact with others and frequent hand-washing to prevent the infection and the spread of COVID-19 among people living in Tokyo. We also examined the factors associated with these behaviors during the declaration of emergency.Methods　An online survey was conducted from April 26 to 29, 2020, approximately 20 days after the declaration of the emergency, among men and women aged 20-69 years living in Tokyo. The study framework was based on the protection motivation theory, which explains the risk-reducing behaviors, and focus theory of normative conduct, which explains the effect of others' behavior on one's own behavior. The frequency of behaviors like avoiding going out or coming in contact with others and frequent hand-washing, as well as the perception of the risk of COVID-19 during the week preceding the survey, were assessed. Each preventive action was evaluated based on the following factors: perceived effectiveness (response efficacy), perceived practicability (self-efficacy), necessary cost (response cost), and perceptions of how much should be done (injunctive norm) and how well others are doing it (descriptive norm). Hierarchical multiple regression analysis with these behaviors as outcomes were performed.Results　This study included 1,034 participants (50.3% male, mean age 44.82 years, standard deviation 14.00 years). The analyses of the frequency of avoiding going out or coming in contact with others showed that the injunctive norm was positively associated with the behavior (standardized partial regression coefficient (ß)=0.343, P<0.001), while the descriptive norm was negatively associated with the behavior (ß=-0.074, P=0.010). Furthermore, the two-way interaction between risk perception, response efficacy, and self-efficacy was significant (ß=0.129, P<0.001), indicating that risk perception was positively associated with the behavior only when either response efficacy or self-efficacy was low. A similar analysis conducted for hand-washing behavior revealed that injunctive norm (ß=0.256, P<0.001) and response efficacy (ß=0.132, P<0.001) were positively associated with the behavior, while the response cost (ß=-0.193, P<0.001) was negatively associated with the behavior.Conclusion　Some variables in the protection motivation theory and the focus theory of normative conduct were related to the behavior for the prevention of COVID-19. The results suggest that the application of these theories is useful in future studies.