EBF1 Limits the Numbers of Cochlear Hair and Supporting Cells and Forms the Scala Tympani and Spiral Limbus during Inner Ear Development.

Early B-cell factor 1 (EBF1) is a basic helix-loop-helix transcription factor essential for the differentiation of various tissues. Our single-cell RNA sequencing data suggest that Ebf1 is expressed in the sensory epithelium of the mouse inner ear. Here, we found that the murine Ebf1 gene and its protein are expressed in the prosensory domain of the inner ear, medial region of the cochlear duct floor, otic mesenchyme, and cochleovestibular ganglion. Ebf1 deletion in mice results in incomplete formation of the spiral limbus and scala tympani, increased number of cells in the organ of Corti and Kölliker's organ, and aberrant course of the spiral ganglion axons. Ebf1 deletion in the mouse cochlear epithelia caused the proliferation of SOX2-positive cochlear cells at E13.5, indicating that EBF1 suppresses the proliferation of the prosensory domain and cells of Kölliker's organ to facilitate the development of appropriate numbers of hair and supporting cells. Furthermore, mice with deletion of cochlear epithelium-specific Ebf1 showed poor postnatal hearing function. Our results suggest that Ebf1 is essential for normal auditory function in mammals.

Detection of Tip Fold-Over of the Slim Modiolar Electrode Using Intraoperative Mobile Cone-Beam Computed Tomography.

OBJECTIVE: This study aimed to evaluate the importance of mobile cone-beam computed tomography in detecting tip fold-over of a slim modiolar electrode within the cochlea during surgery. STUDY DESIGN: Retrospective case review. SETTING: Tertiary medical center. METHODS: From January 2020 to June 2022, 33 ears of 30 patients with normal cochlear morphology underwent cochlear implantation with slim modiolar electrodes and intraoperative mobile cone-beam computed tomography imaging. Furthermore, we retrospectively reviewed the medical records and images. RESULTS: The tip fold-over of the electrodes was detected using mobile cone-beam computed tomography in 3 out of 33 ears (9.1%). We could not identify the tip fold-over by scouting plain X-ray images in 2 out of 3 cases before taking the cone-beam computed tomography images. Electrode removal and reinsertion were performed before wound closure and the successful reinsertion was confirmed by mobile cone-beam computed tomography. The folded electrode tips were located at 238.8°, 152°, and 185.8°. CONCLUSION: Intraoperative mobile cone-beam computed tomography is useful in detecting the tip fold-over of the slim modiolar electrodes during surgery. Therefore, it was possible to reinsert the electrodes in all cases before closing the wound, eliminating the need for revision surgeries. Moreover, the analysis of mobile cone-beam computed tomography images may help to elucidate the mechanisms of electrode tip fold-over.

Function of bidirectional sensitivity in the otolith organs established by transcription factor Emx2.

Otolith organs of the inner ear are innervated by two parallel afferent projections to the brainstem and cerebellum. These innervations were proposed to segregate across the line of polarity reversal (LPR) within each otolith organ, which divides the organ into two regions of hair cells (HC) with opposite stereociliary orientation. The relationship and functional significance of these anatomical features are not known. Here, we show regional expression of Emx2 in otolith organs, which establishes LPR, mediates the neuronal segregation across LPR and constitutes the bidirectional sensitivity function. Conditional knockout (cKO) of Emx2 in HCs lacks LPR. Tmie cKO, in which mechanotransduction was abolished selectively in HCs within the Emx2 expression domain also lacks bidirectional sensitivity. Analyses of both mutants indicate that LPR is specifically required for mice to swim comfortably and to traverse a balance beam efficiently, but LPR is not required for mice to stay on a rotating rod.

Live imaging of hair bundle polarity acquisition demonstrates a critical timeline for transcription factor Emx2.

Directional sensitivity of hair cells (HCs) is conferred by the aymmetric apical hair bundle, comprised of a kinocilium and stereocilia staircase. The mother centriole (MC) forms the base of the kinocilium and the stereocilia develop adjacent to it. Previously, we showed that transcription factor Emx2 reverses hair bundle orientation and its expression in the mouse vestibular utricle is restricted, resulting in two regions of opposite bundle orientation (Jiang et al., 2017). Here, we investigated establishment of opposite bundle orientation in embryonic utricles by live-imaging GFP-labeled centrioles in HCs. The daughter centriole invariably migrated ahead of the MC from the center to their respective peripheral locations in HCs. Comparing HCs between utricular regions, centriole trajectories were similar but they migrated toward opposite directions, suggesting that Emx2 pre-patterned HCs prior to centriole migration. Ectopic Emx2, however, reversed centriole trajectory within hours during a critical time-window when centriole trajectory was responsive to Emx2.

3D reconstruction of cochlea using optical coherence tomography.

Recently, in vivo visualization of the cochlea and the smaller structures inside of it has been achieved by optical coherence tomography (OCT). This makes it possible to use OCT imaging for diagnosis of diseases such as Meniere's disease through measuring the degree of endolymphatic hydrops. To this end, we present a novel method for 3D segmentation of these cochlear OCT images that is based on superpixels and diffusion maps. The method takes as input grayscale volumetric OCT images and outputs a binary image with the segmented cochlea. We show that the proposed method is suitable for segmenting the data for visualization as well as for preprocessing the data for future automated grading of endolymphatic hydrops.

Development of an electrode for the artificial cochlear sensory epithelium.

An artificial cochlear sensory epithelium has been developed on the basis of a new concept that the piezoelectric membrane, which converts mechanical distortion into electricity, can mimic the function of the inner hair cell and basilar membrane of the mammalian cochlea. Our previous research demonstrated that the piezoelectric membrane generated electrical outputs in response to the sound stimulation after implantation into the guinea pig cochlea, whereas electrodes for the stimulation of spiral ganglion neurons have not been fabricated, and a method to fix the device in the cochlea is also required to show proof-of-concept. In the present study, to achieve proof-of-concept of hearing recovery by implantation of the artificial cochlear sensory epithelium, we fabricated new electrodes that stick into the cochlear modiolus, which also play a role in the fixation of the device in the cochlea. The efficacy of new electrodes for fixation of the device in the cochlea and for the stimulation of spiral ganglion neurons was estimated in guinea pigs. Four weeks after implantation, we confirmed that the devices were in place. Histological analysis of the implanted cochleae revealed inconspicuous fibrosis and scar formation compared with the sham-operated specimens (n = 5 for each). The terminal deoxynucleotidyl transferase dUTP nick end labeling method was used to assess cell death due to surgical procedures in the cochleae that were harvested after 1 day (n = 6) and 7 days (n = 6) of implantation; there was no significant increase in apoptotic cell death in the implanted cochleae compared with sham-operated cochleae. In seven animals, serial measurements of electrically evoked auditory brainstem responses were obtained, with the electrode positioned in the scala tympani and with the electrode inserted into the cochlear modiolus. With the insertion of electrodes into the cochlear modiolus, significant reduction was achieved in the thresholds of electrically evoked auditory brainstem responses compared with those placed in the scala tympani (p = 0.028). These findings indicated that the new electrodes efficiently fixed the device in the cochlea and were able to stimulate spiral ganglion neurons.

Therapeutic potential of a gamma-secretase inhibitor for hearing restoration in a guinea pig model with noise-induced hearing loss.

BACKGROUND: Notch signaling plays a crucial role in the fate determination of cochlear progenitor cells, hair cells, and supporting cells in the developing cochlea. Recent studies have demonstrated the temporal activation of Notch signaling in damaged mature cochleae, and have demonstrated the induction of new hair cells by pharmacologically inhibiting Notch signaling. The present study aimed to illustrate the feasibility of pharmacologically inhibiting Notch signaling by using a gamma-secretase inhibitor for treating sensorineural hearing loss. RESULTS: The effect of the sustained local delivery of MDL28170, a gamma-secretase inhibitor, on hearing and hair cell induction was tested in a guinea pig model with noise-induced hearing loss. MDL28170 was directly delivered into the cochlear fluids via a micro-osmotic pump. Drug application was initiated 7 days after noise exposure. Measurements of auditory brainstem responses revealed better hearing in the MDL28170-treated animals than in the vehicle controls. Histological analysis demonstrated a higher number of outer hair cells in the MDL28170-treated cochleae than the vehicle-treated cochleae. CONCLUSION: These findings strongly suggest that local sustained delivery of a gamma-secretase inhibitor into the cochlea could be a novel strategy for treating acute hearing loss that is refractory to conventional treatment.

In vivo imaging of mouse cochlea by optical coherence tomography.

HYPOTHESIS: Cochlear pathology can be evaluated in living animals using optical coherence tomography (OCT). BACKGROUND: The current imaging methods available for the detailed analysis of cochlear pathology in a clinical setting provide only limited information. Thus, a cochlear imaging modality with high definition is needed for improving the diagnosis of cochlear pathology. OCT has been used in other fields for obtaining high-resolution subsurface images, and its use could potentially be extended to the analysis of cochlear pathogenesis. METHODS: Slc26a4(-/-) mice, which generate endolymphatic hydrops, and their littermates were used in this study. Auditory function was monitored by the auditory brainstem responses (ABR). After the mice were placed under general anesthesia, OCT images of the cochlea were captured. The cochlea was subsequently dissected out and histologically evaluated. Three or 7 days later, the wild-type mice cochleae were visualized again. RESULTS: In ABR assessments, Slc26a4(-/-) mice showed severe hearing loss, while no significant hearing loss was found in Slc26a4(+/-) or Slc26a4(+/+) mice. OCT demonstrated normal morphology in the cochlea of both Slc26a4(+/-) and Slc26a4(+/+) mice, including the location of Reissner's membrane. Meanwhile, in Slc26a4(-/-) mice, obvious dislocation of Reissner's membrane was observed, indicating severe endolymphatic hydrops. These findings in the OCT images were consistent with the histologic results for the cochlear morphology, as observed with hematoxylin and eosin staining. Three or 7 days later, wild-type cochleae were successfully visualized using OCT, and no otitis media or labyrinthitis was observed. CONCLUSION: OCT can be applied in the detection of endolymphatic hydrops in living mice, indicating the potential of OCT for cochlear imaging analyses for clinical use in the near future.

Suture granuloma showing false-positive finding on PET/CT after head and neck cancer surgery.

We report herein two cases of suture granuloma showing focal intense 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG)-uptake in positron emission tomography (PET). Follow-up FDG-PET after surgical intervention for head and neck cancer revealed lesions with high FDG-uptake, which were highly suspected of being a recurrent tumor. The lesions were subjected to excisional biopsy for definitive diagnosis. Histopathological examination proved them to be suture granulomas caused by non-absorbable silk sutures. It should be emphasized that suture granulomas can show false-positive findings on FDG-PET, thus requiring differential diagnosis from recurrent tumors.

18F-fluoromisonidazole positron emission tomography before treatment is a predictor of radiotherapy outcome and survival prognosis in patients with head and neck squamous cell carcinoma.

OBJECTIVE: To evaluate the usefulness of [(18)F]fluoromisonidazole ([(18)F]FMISO)-positron emission tomography (PET) prior to the treatment of head and neck squamous cell carcinoma. METHODS: Seventeen patients with untreated HNSCC underwent pretreatment [(18)F]FMISO PET. Six of them underwent definitive surgery and the remaining 11 definitive (chemo-)radiotherapy. We evaluated 30 lesions from the 17 patients. SUVmax and tumor-to-muscle ratios (TMR) were measured as hypoxia indicators. Tumors equal to or above the median value were defined as tumor with high uptake of [(18)F]FMISO and those below as tumor with low uptake of [(18)F]FMISO in both indicators. Local control rates with radiotherapy, event-free survival and disease-specific survival (DSS) rates with radiotherapy or operation were compared. RESULT: [(18)F]FMISO-PET imaging of 30 lesions resulted in a SUVmax median value of 2.3 and a TMR median value of 1.3. Local control rates with radiotherapy (20-month median follow-up duration) were significantly lower in the tumor group with high uptake of [(18)F]FMISO compared to the tumor group with low uptake of [(18)F]FMISO using either SUVmax or TMR as the hypoxic indicator (P = 0.02 and 0.04, respectively). DSS rate with radiotherapy or operation (21-month median follow-up duration) was significantly lower in the patient group with high uptake of [(18)F]FMISO compared to the patient group with low uptake of [(18)F]FMISO defined by SUVmax (P = 0.04), but was not by TMR (P = 0.57). CONCLUSIONS: Radiotherapy outcome and survival prognosis (radiotherapy or operation) in HNSCC may be predicted by carrying out [(18)F]FMISO PET before treatment.

[A case of relapsing polychondritis with respiratory symptom manifestation alone].

Relapsing polychondritis, a comparatively rare condition systemically affecting organs containing collagen, such as cartilage tissue, is diagnosed based on clinical manifestations and pathological findings. Our case report involves a respiratory symptom alone. A 65-year-old man seen for fever and dyspnea was found in computed tomography and endoscopy to have subglottic and tracheal stenosis, necessitating tracheostomy and tracheal cartilage biopsy. Pathologically bony cartilage change was seen but no definite auricular inflammation findings. Additional auricular cartilage biopsy, showed no inflammation. Residual auricular cartilage scarring, however, indicated cartilage destruction by previous inflammation or trauma, yielding a final diagnosis of relapsing polychondritis. Steroid therapy quickly relieved symptoms. Auricular cartilage biopsy thus proved useful in definitively diagnosing this condition.

Sequential FDG-PET/CT after neoadjuvant chemotherapy is a predictor of histopathologic response in patients with head and neck squamous cell carcinoma.

PURPOSE: To evaluate whether 2-deoxy-2-[(18)F]fluoro-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) more accurately predicts the histopathologic response to neoadjuvant chemotherapy (NAC) than magnetic resonance imaging (MRI) in patients with head and neck squamous cell carcinoma (HNSCC). PROCEDURES: Sixteen patients with HNSCC underwent FDG-PET/CT and MRI scans before and after one cycle of NAC, followed by surgical resection. The 26 surgically resected specimens of the 16 patients were analyzed. Decreases in maximum standardized uptake value (SUV(max)) or in tumor maximum size (diameter(max)) were calculated, and their accuracies for the prediction of histopathologic response were evaluated. RESULTS: In histopathologic responders (n = 7), percent decreases in SUV(max) were significantly higher (P < 0.001) than in non-responders (n = 19). Applying a cut-off point of 55.5%, the histopathologic response could be predicted with a sensitivity and specificity of 86% and 95%, respectively. CONCLUSION: FDG-PET/CT can predict histopathologic NAC responses with higher accuracy than MRI in HNSCC patients.

[Two cases of intractable malignant external otitis with skull base osteomyelitis alleviated by intraarterial antibiotic administration].

Malignant external otitis (MEO) is a devastating external auditory canal infection usually occurring in the elderly with diabetes. MEO often progresses to potentially lethal skull base osteomyelitis (SBO) complications such as meningitis or multiple cranial nerve palsies. Poor vascularity in affected tissue due to diabetic microangiopathy and Pseudomonal infection is thought responsible for refractory infection. We conducted intraarterial antibiotic infusion (IA) in the external carotid artery of two subjects with intractable MEO deteriorating after long-term intravenous antibiotic administration with surgical debridement. IA raised the antibiotic concentration in infectious tissue. Clinical MEO manifestation was relieved just after starting IA, and IA therapy was followed by additional long-term intravenous and oral antibiotic administration, dramatically improving MEO while leaving only minimal infection at the skull base. These results demonstrate IA effectiveness in treating refractory MEO.

[Cystic parotid gland lesion evaluation].

OBJECTIVES: We evaluated differential diagnoses of cystic parotid gland lesions and the efficacy of preoperative diagnosis. MATERIALS AND METHODS: Of 191 parotid gland nodules resected between January 2003 and October 2008, 167 (87%) were benign and 24 (13%) malignant. Thirty-five parotid gland nodules whose components were almost cystic were enrolled in this study. All cystic lesions were retrospectively evaluated with respect to preoperative diagnostic examinations and histopathological confirmed diagnosis. Cystic components in surgical specimens were also evaluated histopathologically. The relationships with magnetic resonance imaging (MRI) findings and histopathological confirmed diagnosis were studied. RESULTS: Of 35 cystic lesions, 11 were complete cystic masses and had no mural nodules, while remaining 24 were incomplete and had mural nodules. Histopathological examinations showed that 5 were nonneoplastic, 27 were cystic degenerations of benign tumors, and 3 were cystic degenerations of malignant tumors. In the 11 complete cysts, preoperative diagnosis could not be made using any modality, whether with FNAC, salivary scintigraphy, or 67-gallium citrate scintigraphy. Of 24 incomplete cysts, only 9 cystic Warthin tumors were diagnosed correctly before surgery. Studies of cystic components in MRI and histopathology suggested that hemorrhagic degeneration of malignant tumors should be kept in mind for cystic lesions showing hemorrhagic portions. CONCLUSIONS: Cystic parotid gland lesions are difficult to diagnose correctly before surgery, but the evaluation of cystic components by MRI and FNAC is helpful in differentiating between benign and malignant tumors.

Successful treatment of locally advanced anaplastic thyroid carcinoma by chemotherapy and hyperfractionated radiotherapy.

The authors report a case of anaplastic thyroid carcinoma which was treated with chemotherapy and radiotherapy and proved to achieve pathological CR (complete response) after a radical operation. A 53-year-old female presented with a mass of about 4 cm in diameter arising from the left lobe of her thyroid and surrounding her cervical esophagus. Pre-operative aspiration cytology and open biopsy revealed the tumor was a giant cell anaplastic carcinoma. There was no sign of distant metastasis. Two cycles of chemotherapy were very effective in treating the tumor but regrowth appeared to occur during hyperfractionated radiotherapy. A radical operation, including a resection of the larynx, cervical trachea and esophagus, was successfully performed and no living cancer cells, only granulation and necrosis, were observed in the operation specimen. The patient has been alive for over 2 years since without any evidence of recurrence.

Cortical activation during optokinetic stimulation - an fMRI study.

CONCLUSION: Activation of cortical areas related to visual motion processing and control of eye movement, and deactivation of parieto-insular vestibular cortices (PIVC) were revealed by functional magnetic resonance imaging (fMRI) with small-field optokinetic stimulation (OKS). The results agreed well with those of previous studies, which indicates that the current protocol is reliable enough to be used as a clinical examination. OBJECTIVES: To propose an fMRI set-up with OKS that is reliable and simple enough to be performed as a clinical test. SUBJECTS AND METHODS: Ten right-handed healthy volunteers participated in this study. fMRI was used to measure blood oxygen level-dependent (BOLD) signal increases (contrast: OKS - rest) and decreases (contrast: rest - OKS) during small-field OKS. Functional images were acquired using a standard clinical scanner operating at a magnetic field strength of 1.5 T. The data were analyzed by statistical parametric mapping (SPM2), and the significance level was set at p<0.001, uncorrected. RESULTS: BOLD signal increases were observed in the visual association area of both hemispheres (BA19) (MT/V5), primary visual cortex (BA17) of the right hemisphere, bilateral superior parietal lobules (BA7), and bilateral frontal eye fields (BA6). Decreases of BOLD signals were observed in the PIVC bilaterally.

Brain metabolism of children with profound deafness: a visual language activation study by 18F-fluorodeoxyglucose positron emission tomography.

CONCLUSION: The use of fluorodeoxyglucose positron emission tomography (FDG-PET) with a visual language task provided objective information on the development and plasticity of cortical language networks. This approach could help individuals involved in the habilitation and education of prelingually deafened children to decide upon the appropriate mode of communication. OBJECTIVES: To investigate the cortical processing of the visual component of language and the effect of deafness upon this activity. SUBJECTS AND METHODS: Six prelingually deafened children participated in this study. The subjects were numbered 1-6 in the order of their spoken communication skills. In the time period between an intravenous injection of 370 MBq 18F-FDG and PET scanning of the brain, each subject was instructed to watch a video of the face of a speaking person. The cortical radioactivity of each deaf child was compared with that of a group of normal- hearing adults using a t test in a basic SPM2 model. RESULTS: The widest bilaterally activated cortical area was detected in subject 1, who was the worst user of spoken language. By contrast, there was no significant difference between subject 6, who was the best user of spoken language with a hearing aid, and the normal hearing group.