研究者詳細 - 西山　崇経

論文 - 西山　崇経

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Cell-specific α and β subunit expression patterns of Na+/K+-ATPases in the common marmoset cochlea

Hosoya M., Ueno M., Shimanuki M.N., Nishiyama T., Oishi N., Ozawa H.

Scientific Reports 15 （ 1 ） 26814 2025年12月

High potassium concentration in the cochlear endolymph electrically drives hair cell activity. Sodium potassium ATPase (Na+/K+-ATPase) is an essential pump for ion homeostasis in the cochlea. Most of our knowledge regarding Na+/K+-ATPase has been obtained from rodent models, and knowledge of its distribution in primates, including humans, is limited. This study investigated the distribution of Na+/K+-ATPase in a common marmoset primate model. We investigated expression patterns of Na+/K+-ATPase α1 (ATP1A1), Na+/K+-ATPase α2 (ATP1A2), Na+/K+-ATPase α3 (ATP1A3), Na+/K+-ATPase β1 (ATP1B1), Na+/K+-ATPase β2 (ATP1B2), and Na+/K+-ATPase β3 (ATP1B3) in the cochlea of the neonates and the embryos of the common marmoset. We have described the distributions of specific pairs of Na+/K+-ATPase α and β subunits in each cochlear part, including spiral ganglion neurons, stria vascularis, and the organ of Corti. We also described developmental changes in Na+/K+-ATPases in common marmosets. The distribution of Na+/K+-ATPases in the common marmoset is similar to that in humans and is suitable for furthering our understanding of human cochlear development. The distribution established in this report will aid the study of primate-specific ion homeostasis in the inner ear.

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Relationship between hearing thresholds and cognitive function in hearing aid non-users and long-term users post-midlife

Nishiyama T., Kimizuka T., Kataoka C., Tazoe M., Sato Y., Hosoya M., Shimanuki M.N., Wakabayashi T., Ueno M., Ozawa H., Oishi N.

Npj Aging 11 （ 1 ） 14 - 14 2025年12月

The extent of hearing loss requiring hearing aid (HA) to prevent cognitive decline is unclear; we assessed this post-midlife along with the relationship between hearing thresholds and cognitive function in those who had never used HA (non-users) or used HAs for >3 years (long-term users). This study comprised 117 individuals ≥55 years with an average hearing threshold of ≥25 dB HL in their better ear and 55 of the non-users and 62 of the long-term users. The Mini-Mental State Examination, the Symbol Digit Modalities Test (SDMT), and pure-tone and sound-field audiometry were assessed. Mean ± SD hearing levels of the non-user and long-term user group were 40.83 ± 8.16 and 51.13 ± 14.80 dB HL. Non-users showed a significant association (P = 0.01) between the hearing thresholds and SDMT scores, with a cutoff value of above 38.75 dB HL identified as affecting cognitive function. There were no significant associations for long-term users.

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Course of a sudden sensorineural hearing loss case diagnosed as intra-labyrinthine hemorrhage with MRI in the early phase

Ide K., Hosoya M., Nishiyama T., Shimanuki M.N., Ueno M., Ozawa H., Oishi N.

Auris Nasus Larynx 52 （ 4 ） 479 - 483 2025年08月

ISSN 03858146

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.

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A small vestibular schwannoma with preoperative facial palsy treated via retrolabyrinthine approach

Hatomi S., Hosoya M., Ueno M., Shimanuki M.N., Nishiyama T., Ozawa H., Oishi N.

Auris Nasus Larynx 52 （ 3 ） 216 - 221 2025年06月

ISSN 03858146

Facial nerve paralysis caused by a vestibular schwannoma is a rare but critical symptom; however, few reports have focused on preoperative facial nerve palsy from the viewpoint of treatment. In addition, its mechanism is not fully understood. We report a rare case of preoperative facial nerve palsy that improved after the surgical resection of a small vestibular schwannoma with hearing preservation. A small vestibular schwannoma within the internal auditory canal caused acute deafness and facial paralysis in a 51-year-old woman. Conservative treatment was initially administered, but severe hearing loss and facial paralysis persisted for 3 months after onset. Subsequently, we performed tumor resection using the retrolabyrinthine approach. The tumor, which compressed the cochlear and facial nerves, was almost completely removed under continuous intraoperative monitoring to preserve the facial nerve function. “Wait and scan” is generally recommended for vestibular schwannomas within the internal auditory canal. However, this case suggests that early successful surgery, at least in selected cases, can improve paralysis without hearing deterioration and maintain the patient's quality of life.

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Noise-Induced Hearing Loss: Overview and Future Prospects for Research on Oxidative Stress

Kitama T., Nishiyama T., Hosoya M., Shimanuki M.N., Ueno M., You F., Ozawa H., Oishi N.

International Journal of Molecular Sciences 26 （ 10 ） 2025年05月

ISSN 16616596

Noise-induced hearing loss (NIHL) is a common type of sensorineural hearing loss caused by exposure to high-intensity noise that leads to irreversible cochlear damage. Despite extensive research on cochlear pathophysiology, the precise mechanisms remain unclear, and no established treatment exists. This is due to the challenges in imaging and the inability to perform biopsies in human patients. Consequently, animal models, particularly mice, have been widely used to study NIHL. Clinically, NIHL presents as either a temporary threshold shift, in which hearing recovers, or a permanent threshold shift, which results in an irreversible loss. Histopathological studies have identified the key features of NIHL, including outer hair cell loss, auditory nerve degeneration, and synaptic impairment. Recent findings suggest that oxidative stress and inflammation are major contributors to NIHL, highlighting the potential for therapeutic interventions, such as antioxidants and anti-inflammatory agents. Given the increasing prevalence of NIHL owing to occupational noise exposure and personal audio device use, addressing this issue is a pressing public health challenge. This review summarizes the clinical features, underlying mechanisms, and emerging treatment strategies for NIHL while identifying current knowledge gaps and future research directions.

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Preoperative cVEMP Results Predict Developing Prolonged Dizziness After Vestibular Schwannoma Surgery

Ueno M., Hosoya M., Shimanuki M.N., Nishiyama T., Ozawa H., Oishi N.

Otology and Neurotology 46 （ 4 ） 453 - 459 2025年04月

ISSN 15317129

Objective: To assess pretreatment factors including preoperative vestibular function tests evaluated using cVEMP and caloric tests, which correlate with the development of prolonged dizziness after vestibular schwannoma resection. Study Design: Retrospective cohort study. Setting: Academic tertiary referral centers. Patients: Patients with vestibular schwannoma who underwent surgery and completed preoperative vestibular function tests and questionnaires. Intervention: Diagnostic. Main Outcome Measures: Participants were divided into prolonged dizziness and nonprolonged dizziness groups according to their postoperative DHI scores. The rates of abnormal results of preoperative vestibular function tests (caloric test, cVEMP), including other factors such as preoperative HADS scores, were compared. Furthermore, univariate logistic regression analysis was performed with the DHI score at 3 months as the dependent variable. Results: Of the whole 45 participants, 14 (31%) developed prolonged dizziness postoperatively. The proportion of participants with abnormal cVEMP results was significantly lower in the prolonged dizziness group (7.1%) than in the nonprolonged dizziness group (42%). Other factors did not show any significant differences. Univariate analysis showed that only the cVEMP results correlated with the postoperative DHI score (OR = 9.39, 95% CI [1.56, 181.3], p < 0.05). About 70% of patients with prolonged dizziness continued to exhibit high DHI scores at 6 months after surgery; however, about half of them recovered by 1 year. Conclusion: Vestibular schwannoma patients with normal preoperative cVEMP results tended to develop prolonged dizziness after resection compared to those with abnormal results. Preoperative cVEMP results enable physicians to predict whether vestibular schwannoma patients undergoing resection would likely develop prolonged dizziness postoperatively.

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Closedness of Acoustic Coupling and Audiological Measures Are Associated with Individual Speech-in-Noise Benefit From Noise Reduction in Hearing Aids *

Jürgens T., Ihly P., Tchorz J., Nishiyama T., Tanaka C., Suzuki D., Shinden S., Kitama T., Ogawa K., Zaar J., Laugesen S., Jones G., Vatti M., Santurette S.

Trends in Hearing 29 23312165251325983 2025年01月

The combination of directional microphones (DIR) and spectral noise reduction (NR) is a common technique in hearing aid signal processing, for improving speech intelligibility in spatial acoustic scenarios. The benefit from DIR + NR varies considerably across individuals, which impedes prescribing the optimal strength of such processing during hearing aid fitting. The goal of this study was to investigate the correlation of four audiological factors with the benefit of speech reception thresholds (SRTs) from DIR + NR: the closedness of the acoustic coupling in the ear canal, audible contrast thresholds test (ACT™), the audiogram, and age. As part of a larger field study, 123 experienced hearing aid users in two centers in Germany and Japan were fitted bilaterally with the same hearing aids. SRTs were obtained with and without strong DIR + NR in a spatial speech-in-noise scenario before and after the field trials. Closedness of acoustic coupling was found to have the strongest correlation with SRT benefit from DIR + NR (most likely dominated by DIR rather than NR processing), followed by audible contrast thresholds (ACT) and the audiogram, both with the same significantly weaker correlation. Age was not correlated with the benefit from DIR + NR. The results suggest fitting hearing aid users irrespective of age with as-closed-as-possible acoustic coupling to maximize the benefit of DIR + NR. Furthermore, the closedness of acoustic coupling in combination with ACT or the audiogram may serve audiologists in predicting individual speech intelligibility benefits from strong DIR + NR for better guidance to set its strength during hearing aid fitting.

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Novel continuous and quantitative intraoperative facial nerve-monitoring system for temporal bone lesions

Hosoya M., Iwabu K., Wakabayashi T., Shimanuki M.N., Nishiyama T., Ueno M., Ozawa H., Oishi N.

European Archives of Oto Rhino Laryngology 2025年

ISSN 09374477

Objective: Intraoperative systems for monitoring facial nerve function, in which temporal electrical stimulation is applied to the facial nerve through electrodes, are used in many surgeries requiring facial nerve preservation; however, continuous stimulation or quantitative evaluation of facial nerve function is difficult with this approach. We examined the usefulness of a continuous and quantitative facial nerve-monitoring system for temporal bone lesions by using our experience to modify the existing methods used for cases involving vestibular schwannomas. Study design: Retrospective observational study. Setting: Department of Otorhinolaryngology-Head and Neck Surgery at our hospital. Methods: We modified the electrode placement and examined the usefulness of the modified system under several conditions. The study population consisted of patients who were operated on for temporal bone lesions at our department and underwent continuous nerve monitoring using the modified system. Case details, electrode-placement sites, and facial nerve function data before and after the surgery were obtained and retrospectively evaluated. Results: Electrodes were placed safely during surgery in all cases. No obvious deterioration in facial nerve function was observed, except in one case. Conclusion: The advantages of this system include its ability to perform quantitative intraoperative evaluations and prevent unexpected nerve damage in cases where the facial nerve shows complicated pathways. This monitoring system is useful, even in complex temporal bone surgeries.

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A primate model animal revealed the inter-species differences and similarities in the subtype specifications of the spiral ganglion neurons

Hosoya M., Ueno M., Shimanuki M.N., Nishiyama T., Oishi N., Ozawa H.

Scientific Reports 14 （ 1 ） 25166 2024年12月

Type I spiral ganglion neurons are peripheral neurons essential for hearing perception. While they can be subdivided in mice based on characteristic gene expression patterns, detailed examinations of these subtypes in primates and humans are lacking. In this study, we investigated the developmental subtypes of spiral ganglion neurons in the common marmoset (Callithrix jacchus). We confirmed that Type I spiral ganglion can be divided based on the characteristic gene expression patterns of several marker genes. However, some combinations of these genes differ from those in rodents, suggesting common marmoset's suitability for advancing our understanding of human cochlear development. Additionally, identifying the essential time points for subtype specifications and subsequent maturation will aid in studying the primate-specific developmental biology of the inner ear. This could lead to new treatment strategies for hearing loss in humans and be valuable for studying age-related hearing loss, as well as designing regenerative therapies.

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Detailed characterization of auditory neuropathy in Perrault syndrome with TWNK variants

Shimanuki M.N., Hosoya M., Nishiyama T., Wakabayashi T., Ueno M., Ozawa H., Mutai H., Nara K., Matsunaga T., Oishi N.

Auris Nasus Larynx 51 （ 6 ） 933 - 939 2024年12月

ISSN 03858146

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.

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小児症例における軟骨伝導補聴器の有用性・臨床的特徴の検討

小口慶悟, 西山崇経, 文入悠, 大石直樹

小児耳鼻咽喉科（日本小児耳鼻咽喉科学会） 45 （ 2 ） 149 - 154 2024年12月

ISSN 0919-5858

軟骨伝導補聴器は成人と小児で適応や購入理由・価格が異なるため別々に検討することが望ましいが,小児単一の報告は極めて少ない.今回我々は,軟骨伝導補聴器を試聴した20歳以下の小児症例68例を振り返り,対象における補聴器の継続率,継続群・返却群における臨床的特徴,装用効果などを検討した.全体の継続率は72%で,疾患別では両側外耳道閉鎖/狭窄群63%,片側外耳道閉鎖/狭窄群79%,外耳道開放群25%であった.年齢が上がるにつれて継続率が低下する傾向が見られた.継続群と返却群のファンクショナルゲインに有意差はなかった.購入・継続の判断には装用効果だけでなく,費用や装用感も影響していた.片側例では両耳聴効果や方向感の改善が高い継続率につながった.一方,外耳道開放例では気導補聴器との比較で継続率が低かった.本研究により,小児症例に対する軟骨伝導補聴器の有用性が示され,積極的に試聴してもらうことの重要性が示唆された.(著者抄録)

TRT(tinnitus retraining therapy)18年間の統計から　治療器の推移について

伊藤まり, 小川郁, 大石直樹, 西山崇経, 田路正夫

耳鼻咽喉科・頭頸部外科（(株)医学書院） 96 （ 13 ） 1166 - 1169 2024年12月

ISSN 0914-3491

＜文献概要＞はじめに　耳鳴再訓練法(tinnitus retraining therapy:TRT)とは1980年後半にPawel Jastreboffによって提唱された音響療法と教育カウンセリングで成り立っている治療法である。TRTは耳鳴を消失させることが目的ではなく脳に順応を起こすことで耳鳴の苦痛を減少させる治療である。耳鳴治療器(tinnitus control instrument):サウンドジェネレーター(sound generator:SG)の作用機序は,静寂を避け,耳に雑音を与えることにより大脳皮質における耳鳴の信号のコントラストを減弱させ耳鳴に対する過敏性を減らすように働きかけ,耳鳴に対する順応を起こすとされている。また補聴器の作用機序は,補聴器による外界音の入力によって(1)耳鳴を紛らわせること,(2)蝸牛障害による末梢入力低下により上昇した聴覚中枢での神経活性を抑制することとされている。Jastreboffが提唱するプロトコールでは難聴の自覚のない耳鳴症例ではSGを,難聴の自覚のある耳鳴症例では補聴器を推奨している(表1)。本邦においては2001年の松田による報告以来,TRTを行う施設は増加した。筆者が2004年4月～2022年3月の18年間でTRTを施行し購入された治療器は,SG,補聴器,SG付き補聴器,一側性難聴に対するCROS補聴器であった。本稿では購入された治療器の個数の推移について報告する。

Sarcopenia as a predictive factor for febrile neutropenia during induction chemotherapy in head and neck squamous cell cancer

Kasahara K., Shigetomi S., Sato Y., Imanishi Y., Ikari Y., Nishiyama T., Matsui Y., Shinden S., Ozawa H., Kono T.

Auris Nasus Larynx 51 （ 6 ） 971 - 975 2024年12月

ISSN 03858146

Objective: Febrile neutropenia (FN) is the most serious toxicity in patients with head and neck squamous cell carcinoma (HNSCC) treated with induction chemotherapy (IC). Although it is well-known that sarcopenia is a risk factor for severe toxicity of (chemo)radiotherapy, the data on the association between sarcopenia and FN during IC in HNSCC patients is rare. This study determined the impact of sarcopenia on FN during IC. Methods: IC-treated patients with HNSCC were enrolled in this study. Skeletal muscle mass (SMM) at the C3 vertebral body was used to define sarcopenia from computed tomography (CT) scans. To determine the predictive effect of low SMM on FN, logistic regression analysis was performed. Results: In this study, 71 patients were included, of whom 28 had low SMM and 14 experienced FN. In multivariate analysis, low SMM and high CRP were the independent predictive factors for FN. The combination index of sarcopenia and CRP showed a greater odds ratio than sarcopenia alone suggesting a more significant predicting indicator. Conclusions: Sarcopenia defined by CT imaging is associated with FN in patients with HNSCC treated with IC. The combination of sarcopenia and high CRP is a more significant risk factor, and it helps determine patients at risk of FN during IC.

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Long-term hearing prognosis after vestibular schwannoma surgery with retrolabyrinthine approach

Hosoya M., Nishiyama T., Shimanuki M.N., Ueno M., Ozawa H., Miyazaki H., Oishi N.

European Archives of Oto Rhino Laryngology 281 （ 11 ） 5699 - 5707 2024年11月

ISSN 09374477

Purpose: The retrolabyrinthine approach is a surgical method designed to preserve hearing after surgery. When paired with intraoperative monitoring and an endoscope, this approach has demonstrated high rates of postoperative hearing preservation. However, the long-term prognosis of hearing preservation after utilizing this approach for vestibular schwannomas remains unexplored. This study aimed to examine the long-term outcomes of preserved hearing, providing insights into the suitability of the retrolabyrinthine approach for hearing preservation surgery. Methods: This study included 34 patients with preserved hearing after vestibular schwannoma surgery using the retrolabyrinthine approach at a single center. Long-term hearing prognosis and requirement for additional interventions were retrospectively examined. Results: Immediate after post-operative hearing preservation rate was 71.7%. Among the 34 patients with preserved hearing post-vestibular schwannoma surgery, four (11.8%) required additional interventions. Other patients experienced a gradual deterioration in their hearing status, with an approximate 10 dB decline during the 5-year follow-up; however, a serviceable hearing level persisted long after the surgery in these individuals. Conclusions: This study indicated the rationale for the retrolabyrinthine approach as a hearing preservation surgery for vestibular schwannomas, emphasizing its long-term hearing prognosis.

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Characteristics of pure tone audiogram in patients with untreated sporadic vestibular schwannoma: Analysis of audiometric shape and interaural differences stratified by age and mode of onset

Tsuzuki N., Kitama T., Wasano K., Wakabayashi T., Hosoya M., Nishiyama T., Ozawa H., Oishi N.

Auris Nasus Larynx （Auris Nasus Larynx） 51 （ 2 ） 347 - 355 2024年04月

ISSN 03858146

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.

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Binaural hearing aid intervention for a patient with nonserviceable hearing loss after surgery for vestibular schwannoma: A case report

Hosoya M., Iwabu K., Hasebe N., Nishiyama T., Wakabayashi T., Shimanuki M., Ueno M., Ozawa H., Oishi N.

Science Progress 107 （ 2 ） 368504241262195 - 368504241262195 2024年04月

ISSN 00368504

A vestibular schwannoma is a benign tumor; however, the schwannoma itself and interventions can cause sensorineural hearing loss. Most vestibular schwannomas are unilateral tumors that affect hearing only on one side. Attention has focused on improving the quality of life for patients with unilateral hearing loss and therapeutic interventions to address this issue have been emphasized. Herein, we encountered a patient who was a candidate for hearing preservation surgery based on preoperative findings and had nonserviceable hearing after the surgery, according to the Gardner–Robertson classification. Postoperatively, the patient had decreased listening comprehension and ability to localize sound sources. He was fitted with bilateral hearing aids, and his ability to localize sound sources improved. Although the patient had postoperative nonserviceable hearing on the affected side and age-related hearing loss on the unaffected side, hearing aids in both ears were useful for his daily life. Therefore, the patient was able to maintain a binaural hearing effect and the ability to localize the sound source improved. This report emphasizes the importance of hearing preservation with vestibular schwannomas, and the demand for hearing loss rehabilitation as a postoperative complication can increase, even if hearing loss is nonserviceable.

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前庭神経鞘腫の耳鼻咽喉科的な臨床症状と治療文献レビュー(Otological clinical symptoms and management of vestibular schwannoma: literature review)

Oishi Naoki, Nishiyama Takanori, Hosoya Makoto, Ueno Masashi, Shimanuki Marie, Wakabayashi Takeshi, Tsuzuki Nobuyoshi, Kitamura Mitsuru, Ozawa Hiroyuki

日本耳鼻咽喉科頭頸部外科学会会報（(一社)日本耳鼻咽喉科頭頸部外科学会） 127 （ 4 ） 493 - 493 2024年04月

ISSN 2436-5793

Prediction of Cochlear Implant Effectiveness with Surface-Based Morphometry

Minami S., Takahashi M., Shinden S., Shirai K., Oishi N., Nishimura H., Masuda M., Masuda S., Nishiyama T., Hosoya M., Ueno M., Kashio A., Yamada H., Matsunaga T., Kaga K., Shintani A., Nemoto K.

Otology and Neurotology （Otology and Neurotology） 45 （ 2 ） 114 - 120 2024年02月

ISSN 15317129

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

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Natural history of hearing and tumor growth in vestibular schwannoma in neurofibromatosis type 2-related schwannomatosis

Wakabayashi T., Tamura R., Karatsu K., Hosoya M., Nishiyama T., Inoue Y., Ogawa K., Kanzaki J., Toda M., Ozawa H., Oishi N.

European Archives of Oto-Rhino-Laryngology （European Archives of Oto-Rhino-Laryngology） 281 （ 8 ） 4175 - 4182 2024年

ISSN 09374477

Objectives: To determine the natural history of hearing loss and tumor volume in patients with untreated neurofibromatosis type 2 (NF2)-related schwannomatosis. Moreover, we statistically examined the factors affecting hearing prognosis. Methods: This retrospective cohort study was conducted on 37 ears of 24 patients with NF2-related vestibular schwannomatosis followed up without treatment for more than 1 year. We obtained detailed chronological changes in the PTA and tumor volume in each case over time, and the rate of change per year was obtained. Multivariate analysis was also conducted to investigate factors associated with changes in hearing. Results: The average follow-up period was approximately 9 years, and hearing deteriorated at an average rate of approximately 4 dB/year. The rate of maintaining effective hearing decreased from 30 ears (81%) at the first visit to 19 ears (51%) at the final follow-up. The average rate of change in tumor growth for volume was approximately 686.0 mm3/year. This study revealed that most patients with NF2 experienced deterioration in hearing acuity and tumor growth during the natural course. A correlation was observed between an increase in tumor volume and hearing loss (r = 0.686; p < 0.001). Conclusions: Although the hearing preservation rate in NF2 cases is poor with the current treatment methods, many cases exist in which hearing acuity deteriorates, even during the natural course. Patients with an increased tumor volume during the follow-up period were more likely to experience hearing deterioration. Trial registration number 20140242 (date of registration: 27 October 2014).

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Development of cochlear spiral ligament fibrocytes of the common marmoset, a nonhuman model animal

Hosoya M., Iwabu K., Kitama T., Nishiyama T., Oishi N., Okano H., Ozawa H.

Scientific Reports （Scientific Reports） 13 （ 1 ） 11789 - 11789 2023年12月

Spiral ligament fibrocytes generate potassium gradients, which hair cells require to convert mechanical sound waves into electrical palsy. Together with the stria vascularis, they regulate endolymph electrolyte homeostasis. Developing spiral ligament fibrocytes and generating endocochlear potential with an appropriate endolymph ion composition are essential for hearing. Understanding spiral ligament fibrocyte development is useful for studying age-related and genetic hearing loss, as well as for regenerative therapy and cochlear immunology. Despite interspecies differences, most studies of cochlear development have been conducted in rodent models due to the difficulty of using human fetal samples. This study investigated the cochlear development of spiral ligament fibrocytes in a small New World monkey species, the common marmoset (Callithrix jacchus). We examined the developmental expression of specific genes in spiral ligament fibrocytes, including those essential for the generation of endolymphatic potential. Our results showed that this animal model of spiral ligament fibrocyte development is similar to that of humans and is a suitable alternative for the analysis of human cochlear development. The time course established in this study will be useful for studying the primate-specific developmental biology of the inner ear, which may lead to novel treatment strategies for human hearing loss.

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