Published papers

Background: Fine-tuned cochlear development is essential for hearing. Owing to the difficulty in using early human fetal samples, most of our knowledge regarding cochlear development has been obtained from rodents. However, several inter-species differences in cochlear development between rodents and humans have been reported. To bridge these differences, we investigated early otic development of a non-human primate model animal, the common marmoset (Callithrix jacchus). Methods: We examined 20 genes involved in early cochlear development and described the critical developmental steps for morphogenesis, which have been reported to vary between rodents and marmosets. Results: The results revealed that several critical genes involved in prosensory epithelium specifications showed higher inter-species differences, suggesting that the molecular process for hair cell lineage acquisition in primates differs considerably from that of rodents. We also observed that the tempo of cochlear development was three times slower in the primate than in rodents. Conclusions: Our data provide new insights into early cochlear development in primates and humans and imply that the procedures used for manipulating rodent cochlear sensory cells cannot be directly used for the research of primate cells due to the intrinsic inter-species differences in the cell fate determination program.

Purpose: Amikacin liposome inhalation suspension (ALIS), which efficiently allows amikacin to reach the pulmonary periphery for effect while minimising systemic adverse effects, was recently approved for treating Mycobacterium avium complex (MAC) infections. The international Phase 3 open-label clinical trials showed promising results, contributing to sputum culture conversion, but few studies have examined the efficacy and adverse effects of ALIS using real-world data. We identified the clinical outcome and adverse effects of ALIS in the early phase of treatment, for more effective and safe use in clinical practice. Patients and Methods: The study population consisted of patients with MAC lung disease (MAC-LD), introduced to ALIS therapy after July 2021 at Keio University Hospital due to poor response to multidrug therapy. The sputum smear/culture results, symptoms, adverse effects, and the serum amikacin concentrations of the early phase of ALIS inhalation therapy were examined. Results: A total of 11 patients (9 women; median age 64.6 years) were included in this study. The median disease duration of MAC-LD was 13.7 years, and all patients exhibited a positive culture at the beginning of ALIS inhalation. Three of the six patients (50.0%) who were initially sputum-smear-positive were confirmed to have become sputum-smear-negative within one month, including one culture conversion. ALIS inhalation therapy caused some adverse effects in nine patients (81.8%); however, no serious systemic adverse effects were observed. The most common adverse effect was hoarseness (72.7%), which mostly occurred around 1 week after initiation. The medians of peak serum amikacin concentrations were 1.4 and 2.3 μg/mL for the first and third inhalations, respectively. Trough serum concentrations just before the third inhalation were <1.2 μg/mL in all patients. Conclusion: ALIS therapy might be a treatment option for patients with refractory MAC infection with long disease duration and a poor response to guideline-based therapy.

Background: The effectiveness of hearing aids for tinnitus patients without hearing loss in conversation-comprehension range and inconvenience in daily communication is unknown. Objective: We aimed to evaluate their therapeutic effect. Materials and methods: We included 91 patients with average hearing levels <30 dBHL. To determine the effects, self-reported questionnaires were used. Data were collected at the entry and 3 months (n = 91) and 1 year (n = 70) after treatment initiation. Results: All scores (mean ± standard deviation) decreased significantly (p < 0.0001) from before treatment to 3 months and 1 year after treatment: tinnitus handicap inventory score: from 56 ± 21 to 17 ± 17 and 13 ± 15; visual analogue scale (VAS) score for tinnitus loudness: from 71 ± 20 to 31 ± 26 and 28 ± 29; VAS score for tinnitus annoyance: 79 ± 20 to 27 ± 25 and 26 ± 30, respectively. Approximately 90% of patients noticed improvements in tinnitus annoyance and loudness, as determined by the questionnaires regarding subjective symptom improvement. Conclusions: Hearing aids may be useful for tinnitus patients without hearing loss and inconvenience in daily communication. Significance: Our findings provide a treatment option for tinnitus patients with an average hearing level of <30 dBHL.

Objectives: Vocal fold medialization surgery is generally considered a phonosurgical procedure for improvement of vocal function in patients with glottic insufficiency. However, the literature describing this procedure for the management of dysphagia is limited. This study aims to assess the effects of medialization surgery on swallowing function in patients with unilateral vocal fold paralysis (UVFP). Methods: We enrolled 32 patients with UVFP undergoing vocal fold medialization surgery (medialization laryngoplasty combined with arytenoid adduction [ML + AA], 12 cases; injection laryngoplasty [IL], 20 cases). We assessed the aerodynamic vocal function including maximum phonation time and mean flow rate to evaluate glottal closure status. The Hyodo score determined by flexible endoscopic evaluation and Functional Oral Intake Scale (FOIS) were evaluated pre- and postoperatively. Results: Almost 60% of patients with UVFP had dysphagia, and one-third were at high risk for aspiration. Aerodynamic parameters effectively improved after IL and ML + AA. With regard to swallowing, both the FOIS and total Hyodo score were significantly improved postoperatively. We found a particularly significant improvement in pharyngeal clearance. However, patients with high vagal nerve paralysis and postoperative insufficient glottal closure showed poor swallowing benefits after the interventions. In patients with recurrent laryngeal nerve palsy, there were no significant differences in postoperative swallowing function between the ML + AA and IL groups. Conclusion: Vocal fold medialization surgery was effective in improving swallowing function in most cases with UVFP, except for those with high vagal paralysis and insufficient postoperative glottal closure. Both IL and ML + AA showed an equivalent effect on swallowing improvement. Level of evidence: 3b.

Objectives: To evaluate the effectiveness of sound therapy using hearing aids in patients experiencing tinnitus with acquired unilateral sensorineural hearing loss. Methods: A total of 97 patients with unilateral tinnitus with acquired ipsilateral sensorineural hearing loss were included. Evaluation involved self-report questionnaires administered at entry, 3 months after treatment, and 1 year after treatment. Results: The mean Tinnitus Handicap Inventory score before treatment decreased significantly (p < 0.01) at 3 months (50.0 ± 24.5-12.7 ± 16.2), and 1 year (53.3 ± 25.5-8.79 ± 13.9), after treatment. Moreover, the visual analog scale score decreased significantly at 3 months (loudness, 69.6 ± 21.9-29.1 ± 27.2; annoyance, 71.1 ± 24.7-22.7 ± 25.5) and 1 year (loudness, 69.8 ± 22.0-21.1 ± 26.1; annoyance, 72.7 ± 25.6-19.4 ± 27.6). Approximately 80-90% of patients noticed improvements in tinnitus annoyance and loudness, as determined by their responses to the questionnaires of subjective symptom improvement. Conclusions: Hearing aids are remarkably effective for patients with unilateral tinnitus with acquired ipsilateral sensorineural hearing loss.

Objective: Pemphigus Vulgaris (PV) is a rare autoimmune disease that could cause laryngeal lesions; however, only a few studies have described the localization of the laryngeal lesions associated with this disease owing to its rarity. Therefore, this study aimed to determine the localization of laryngeal lesions in patients with PV. Methods: Fourteen patients with PV accompanied by laryngeal or pharyngeal lesions, who underwent flexible laryngeal endoscopy performed by laryngologists, were examined retrospectively. Results: The arytenoid area was the most frequently affected site in the larynx, followed by the epiglottis and aryepiglottic folds. Vocal folds and ventricular bands were the least affected. Conclusion: Lesions in the arytenoid area were observed more frequently in this study than in previous studies. This result suggests that a more careful inspection of arytenoid lesions in patients with PV is required under laryngeal fiber observation. Moreover, we proposed a novel classification system for laryngeal findings in patients with PV and a systematic observation method. This novel classification and method would be useful not only for determining the lesions but also for careful inspection in this field. Level of Evidence: 4 Laryngoscope, 134:3719–3725, 2024.

Objective: Asymmetric sensorineural hearing loss (ASHL) is the most common symptom of sporadic vestibular schwannoma (VS). However, there is still no universally accepted MRI protocol for diagnosing VS. This study identified the characteristics of pure tone audiogram (PTA) in patients with VS. Methods: We conducted a retrospective chart review of patients diagnosed with sporadic unilateral VS. In the analysis, we focused on the shape and interaural differences of PTA, stratified by the mode of onset and patient age. Results: In total, 390 patients met the inclusion criteria. The U-shaped audiogram showed the highest proportion in patients with the onset of sudden sensorineural hearing loss (SSNHL). In patients with SSNHL, U-shaped audiograms were younger than other audiograms, and 86.7 % of patients under 40 had U-shaped audiograms. Patients with VS were more likely to have interaural differences at higher frequencies than at lower frequencies. Patients with SSNHL had a significantly higher percentage of interaural differences at 500–4000 Hz than those with onset other than SSNHL (non-SSNHL patients). In addition, non-SSNHL patients had a significant trend toward a higher percentage of interaural differences at all frequencies with increasing age. Conclusion: MRI screening can be considered in patients with SSNHL with U-shaped audiograms under 40 years of age. In ASHL, not SSNHL, MRI screening can be considered for older patients with interaural differences at wider continuous frequencies. Patients with interaural differences at high frequencies had a higher priority than those with interaural differences at low frequencies as indications for MRI screening for VS.

Objective: We aimed to investigate the factors influencing the performance of planned stapedotomies for patients with definite otosclerosis. Methods: We evaluated 152 patients with otosclerosis who were divided into the stapedotomy and non-stapedotomy groups. Their patient backgrounds, pre- and post-operative hearing thresholds, and relationships between their preoperative hearing and stapedotomy conversion rates were compared. Results: A total of 112 (73.7 %) patients underwent planned stapedotomies, and 40 (26.3 %) underwent non-stapedotomy procedures. The complications or postoperative hearing outcomes of the two groups were not significantly different. The non-stapedotomy group included significantly more female patients and left-sided cases and had lower preoperative 4000 Hz air conduction (AC) hearing thresholds than the stapedotomy group. The conversion to a non-stapedotomy procedure was performed for 33 of 77 (42.9 %) patients with preoperative 4000 Hz AC hearing thresholds of 50 dB or less. Conclusion: Patients with definite otosclerosis who were left-sided, those who were female, or those who had low preoperative 4000 Hz AC hearing thresholds had a higher risk of conversion to a non-stapedotomy procedure.

Background: In view of improving biomarkers predicting the efficacy of immunotherapy for head and neck squamous cell carcinoma (R/M HNSCC), this multicenter retrospective study aimed to identify clinical, tumor microenvironmental, and genomic factors that are related to therapeutic response to the anti- Programmed cell death protein 1 (PD-1) antibody, nivolumab, in patients with R/M HNSCC. Methods: The study compared 53 responders and 47 non-responders, analyzing formalin-fixed paraffin-embedded samples using 14-marker multiplex immunohistochemistry and targeted gene sequencing. Results: Of 100 patients included, responders had significantly lower smoking and alcohol index, higher incidence of immune related adverse events, and higher PD-1 ligand (PD-L1) expression in immune cells as well as PD-L1 combined positive score (CPS) than non-responders. The frequency of natural killer cells was associated with nivolumab response in patients with prior cetuximab use, but not in cetuximab-naïve status. Age-stratified analysis showed nivolumab response was linked to high CPS and lymphoid-inflamed profiles in patients aged ≥ 65. In contrast, lower NLR in peripheral blood counts was associated with response in patients aged < 65. Notably, TP53 mutation-positive group had lower CPS and T cell densities, suggesting an immune-excluded microenvironment. Patients with altered tumor suppressor gene pathways, including TP53, CDKN2A, and SMAD4 mutations, had lower CPS, higher smoking index, and were associated with poor responses. Conclusion: Nivolumab treatment efficacy in HNSCC is influenced by a combination of clinical factors, age, prior treatment, immune environmental characteristics, and gene mutation profiles.

Objective: To elucidate the genetic etiology of sporadic vestibular schwannomas (VSs) and investigate the correlation between NF2 inactivation mechanisms and preoperative clinical characteristics, including hearing function and tumor growth. Methods: Nineteen patients who underwent VS resection at our otorhinolaryngology or neurosurgery department between June 2020 and March 2022 were included in this study. Whole-exome sequencing (WES) was performed to detect somatic changes in NF2. Additionally, NF2 promoter methylation status and copy number changes were evaluated using methylation analysis and multiple ligation-dependent probe amplification (MLPA). Preoperative clinical data, including pure tone audiometry, speech discrimination scores, and tumor growth rates, were collected and analyzed for correlations with genetic findings. Results: WES identified somatic alterations in both NF2 alleles in 16 cases (84.2%). The addition of methylation analysis and MLPA confirmed biallelic NF2 inactivation in all cases. NF2 promoter methylation was suggested to be associated with hearing loss and tumor progression. A weak correlation between NF2 expression levels and tumor growth rate was observed (r = 0.21), while no significant correlation was found between NF2 expression and pure tone audiometry or speech discrimination scores. Conclusion: Comprehensive genetic analyses, including WES, methylation analysis, and MLPA, are essential for identifying NF2 inactivation mechanisms in sporadic VSs. The findings suggest that NF2 methylation may contribute to variations in clinical presentation. Further studies with larger cohorts are necessary to clarify the role of epigenetic modifications in disease progression and their potential impact on patient management strategies. Level of Evidence: 4.

Intralabyrinthine hemorrhage (ILH) is a rare differential diagnosis of sudden sensorineural hearing loss. Investigations using magnetic resonance imaging (MRI) in the early phase from the onset are inevitable to diagnose ILH. However, MRI is not usually performed during the early phases of sudden sensorineural hearing loss. Hence, ILH is rarely diagnosed, and the hearing prognosis and vestibular function in patients have been poorly understood. In the present study, we report the detailed course of ILH with relatively good hearing recovery. Additionally, vestibular function recovery was quantitatively examined using a video head impulse test. A 75-year-old man presented at our clinic with a chief complaint of dizziness, sudden hearing loss, left sensorineural hearing loss, and nystagmus. MRI 18 days after onset showed a left ILH. Following treatment with prednisone, the patient's hearing level partially recovered and nystagmus disappeared. Our experience emphasizes that MRI in the early phase is crucial for diagnosing ILH. Furthermore, MRI in the early phase should be considered in cases of sudden sensorineural hearing loss or dizziness and is beneficial for investigating ILH as a subpopulation of sudden sensorineural hearing loss.

Carotid body tumors (CBTs) are neoplasms that occur at the bifurcation of the carotid artery and are pathologically classified as paragangliomas. In the 4th edition of the WHO classification, paragangliomas are categorized as neoplasms with malignant potential. Clinically, about 5% of CBTs present with malignant features such as metastasis. Currently, it is challenging to distinguish between tumors with benign courses and those that present malignantly. Recent advances in genetic testing have elucidated the genetic characteristics of paragangliomas, including carotid body tumors. Over 20 genes have been identified as being involved in tumor development. Particularly in head and neck paragangliomas, abnormalities in genes related to succinate dehydrogenase are frequently observed. Research is ongoing to understand the mechanisms by which these genes contribute to tumor development. The definitive treatment for CBTs is surgical resection. These tumors are prone to bleeding and often adhere firmly to the carotid artery, making intraoperative bleeding control challenging. The risk of lower cranial nerve paralysis is relatively high, and there is a risk of stroke because of manipulation of the carotid artery. Preoperative evaluation with angiography is essential, and a multi-disciplinary surgical team approach is necessary. In cases where the tumor is difficult to resect or has metastasized, radiation therapy or chemotherapy are employed. Clinical trials involving targeted molecular therapies and radiopharmaceuticals have recently been conducted, with some applied clinically. The development of various new treatments is anticipated, providing hope for therapeutic options in refractory cases.

Measurement of thyroglobulin in fine-needle aspirates (FNA-Tg) is useful for the diagnosis of lymph node metastasis in thyroid carcinoma; however, the cutoff value remains unclear, particularly for the differential diagnosis of neck masses. To evaluate the cutoff value of FNA-Tg, we conducted a retrospective study of patients with neck masses outside the thyroid who pre-operatively underwent both FNAC and FNA-Tg, followed by pathological examination at our hospital from October 2015 to September 2020. The cutoff value of FNA-Tg was calculated using the receiver operating characteristic curve. Among 210 lesions, 57 were of thyroid origin and 153 lesions were not of thyroid origin. A high FNA-Tg value was observed in the lesions of thyroid origin (P: 0.001), and the cutoff value at the minimum point of 100% specificity was 32.2 ng/mL with a sensitivity of 87.7%. Regarding the effect of serum anti-Tg antibodies, FNA-Tg values were significantly lower or not significantly different depending on the grouping, warranting further studies. Among the cases with papillary thyroid carcinoma, the sensitivity of FNAC and FNA-Tg was 71.4% and 87.5%, respectively. The cutoff value of FNA-Tg for the differential diagnosis of neck masses was higher compared to previous reports because some metastatic lymph nodes of carcinomas and lesions, other than lymph nodes, exhibited higher FNA-Tg values. Therefore, if FNA-Tg is to be used as a screening test for the differential diagnosis of neck masses in patients without proven thyroid carcinoma, it is necessary to establish a higher cutoff value.

Salivary duct carcinoma (SDC) is an uncommon, high-grade malignancy. Identifying suitable prognostic factors is crucial for developing effective treatment strategies for SDC. p53 Immunohistochemistry (IHC) is a potential prognostic marker for SDC. Traditionally, only the nuclear expression has been considered when evaluating aberrant p53 IHC patterns. However, recent studies on other organ cancers have highlighted the significance of the cytoplasmic p53 expression. We aimed to investigate the prognostic implications of cytoplasmic p53 positivity and its association with TP53 variants in a large cohort of patients with SDC. p53 IHC was performed in 327 patients with SDC who had undergone primary curative resection. Based on the immunostaining patterns, patients were classified into 4 groups: wild-type (WT), overexpression (OE), complete absence (CA), and cytoplasmic (CY). Additionally, the TP53 gene status was analyzed in 239 cases by Sanger and/or next-generation sequencing. The p53 IHC patterns of 327 cases were as follows: WT (n = 125; 38.2%), OE (n = 100; 30.6%), CA (n = 75; 22.9%), and CY (n = 27; 8.3%). A TP53 genetic analysis of 239 cases revealed the following: WT status (n = 80; 33.5%), missense/inframe variants (n = 86; 36.0%), and truncating variants (n = 73; 30.5%). Notably, 24 of the 25 CY cases (96%) harbored TP53 variants, which were predominantly located in the domains responsible for nuclear translocation. Of these, 22 exhibited truncating variants. In a multivariate analysis, CY cases demonstrated significantly shorter disease-free survival (DFS) than WT cases (P = .01). Furthermore, patients with aberrant p53 expression patterns (OE+CA+CY) had significantly worse DFS and overall survival than those with WT (P = .003 and .002, respectively). The presence of TP53 variants was also associated with poorer DFS and overall survival (P = .003 and .02, respectively). Our findings suggest that the cytoplasmic expression of p53 in SDC represents a distinct aberrant pattern underlying characteristic genetic abnormalities and has significant prognostic implications.

Perrault syndrome is an autosomal recessive condition characterized by hearing loss and ovarian failure. Hearing loss in Perrault syndrome has been reported as sensorineural; however, only two cases in a single report have comprehensively investigated hearing in Perrault syndrome with TWNK variant, and the association between this variant and auditory neuropathy has not been established. The proband presented with hearing difficulties and primary amenorrhea. Hearing tests revealed mild hearing loss. Maximum speech intelligibility score was 95 % with normal otoacoustic emission. However, no auditory brainstem responses were observed, leading to the diagnosis of auditory neuropathy. Genetic tests identified compound heterozygous variants of TWNK (p.Ile253Met and p.Arg391His), which lead to the genetic diagnosis of Perrault syndrome. Electrocochleography suggests a decreased cochlear nerve function. The patient's sister was also subsequently genetically diagnosed with Perrault syndrome upon identification of the same TWNK variant and had auditory neuropathy with low-tone hearing loss on pure-tone audiometry. These cases highlight the importance of detailed hearing tests, including auditory brainstem response and genetic tests in patients with Perrault syndrome, even in cases of mild hearing loss, for accurate diagnosis and appropriate management.

Membrane channels play an important role in auditory processes. Connexins and pannexins are membrane channels that exist in the cochlea. Connexin26 and connexin30 have been previously shown to be differentially expressed in the developing cochlea of primates in a species-specific manner. However, whether other connexins and pannexins are also expressed in the developing primate cochlea has not been investigated. In this study, we sought to examine the expression patterns of connexin43, connexin31, and pannexin1 during cochlear development in a primate animal model, the common marmoset, to determine the differences observed between the marmoset and existing rodent models. Our observations revealed both interspecies differences in the expression patterns of these genes and similarities between rodents and primates. These results indicate that the spatiotemporal patterns of connexin and pannexin expression are complex and differ between rodents and primates. They also highlight the importance of carefully observing differences in developmental changes in connexins and pannexins between humans and rodents.

Introduction: Macrophages are essential immune cells in the cochlea that contribute to inflammation, tissue repair, and homeostasis. They also play an important role in local cochlear immunity. The developmental immigration and maturation of macrophages in the cochlea have been investigated and are considered essential for normal hearing acquisition. Most of our current knowledge regarding cochlear development is based on rodent models because of the ethical challenges of using human fetal samples for research. However, inter-species differences between rodents and humans have been reported. In this study, we used a primate animal model to investigate the distributions of macrophages in the developing cochlea. The common marmoset (Callithrix jacchus), a small monkey species that inhabits the New World, was used as the model. Methods: We investigated the distribution of macrophages in the developing cochlea of the common marmoset by performing immunohistochemical analyses of cochlear tissue from common marmoset embryos at different development stages. Results: We revealed detailed distribution changes in the macrophages of a primate animal model cochlea. This observation indicates that most of the changes in the general distribution of macrophages were well preserved between rodents and this primate. The distribution changes observed in the common marmoset were also compatible with observations in the human fetus; although, observations in the human fetus are limited. Our observations in this study also revealed several differences between common marmosets and rodents. Conclusion: The time course of immunological development and maturations established in this study will aid in the study of the primate-specific developmental biology of the inner ear. These observations may eventually lead to new therapeutic strategies for hearing loss in humans. In addition, understanding the immunological steady-state of the cochlea may help in the study of age- and genetic-induced hearing loss and in the design of regenerative therapies.

Olfactory neuroblastomas rarely secrete adrenocorticotropic hormone, leading to ectopic adrenocorticotropic hormone syndrome. However, the prevalence, timing, and triggers of ectopic adrenocorticotropic hormone syndrome in patients with olfactory neuroblastomas remain unclear. This study aimed to investigate these factors and conduct a literature review. Fifteen patients with olfactory neuroblastomas who underwent surgery at our institution were included. The prevalence of ectopic adrenocorticotropic hormone syndrome development was assessed by evaluating adrenocorticotropic hormone expression using immunohistochemistry. Furthermore, 26 patients with olfactory neuroblastomas who developed ectopic adrenocorticotropic hormone syndrome from previous reports were reviewed. Among the 15 patients, three (20%) showed adrenocorticotropic hormone-positive tumor cells at the time of initial surgery, and two (13%) developed ectopic adrenocorticotropic hormone syndrome. The timing of developing ectopic adrenocorticotropic hormone syndrome was 2.5 and 10 years following the initial treatment of olfactory neuroblastoma. Based on the literature review, nine patients with recurrent and metastatic olfactory neuroblastoma developed ectopic adrenocorticotropic hormone syndrome after the initial surgery, of whom, three had confirmed disease after developing ectopic adrenocorticotropic hormone syndrome, three developed during disease progression, two developed after receiving chemotherapy, and one developed after undergoing a biopsy. The timing of ectopic adrenocorticotropic hormone syndrome was 2.5–15 years after initial treatment. Our study revealed that acknowledging olfactory neuroblastomas can manifest as ectopic adrenocorticotropic hormone syndrome with a certain low prevalence is crucial. Moreover, our study speculated that tumor stimulation, such as biopsy or chemotherapy, as well as disease progression, could trigger ectopic adrenocorticotropic hormone syndrome onset. Thus, olfactory neuroblastomas can develop into ectopic adrenocorticotropic hormone syndrome, even long after the initial treatment.