Published papers

Rationale: Hypertrophic pachymeningitis (HP) is a local or diffuse fibrous thickness of the dura mater of the brain or spinal cord, caused by infection or connective tissue disease. Headache is the most common clinical symptom, followed by various cranial nerve disorders such as visual impairment, diplopia, and hearing loss. HP can be classified into secondary and idiopathic. Here, we report a case of bilateral progressive profound sensorineural hearing loss diagnosed in a patient with idiopathic HP, where a cochlear implant was effectively used. Patient concerns: The patient was a 77-year-old woman. Hearing loss gradually progressed bilaterally, and magnetic resonance imaging showed a space-occupying lesion with a continuous contrast enhancement in the bilateral internal auditory canals, and diffused dural thickening from the middle to the posterior cranial fossa. Diagnoses: A trans-labyrinthine biopsy was conducted, and a definite diagnosis of idiopathic HP was made. Thickening of the dura mater in the bilateral internal auditory canals was thought to cause profound hearing loss. Interventions and outcomes: A cochlear implant was implemented 4 months after biopsy, and a favorable hearing response was obtained postoperatively. Lessons: This is the first report of a cochlear implant in a patient with idiopathic HP. Cochlear implantation was considered a good treatment for profound hearing loss due to idiopathic HP, which provides a reference for patients to receive timely and correct treatment.

Teratocarcinosarcoma is a rare, highly malignant tumor, that occurs mainly in the nasal cavity and paranasal sinuses. The prognosis is poor because the tumor invades the surrounding tissues even from an early stage. We report a case of sinonasal teratocarcinosarcoma that was treated by transnasal endoscopic skull base surgery and radiotherapy. The patient was a 65-year-old man who presented with a 2-month history of recurrent left epistaxis. Examination revealed a mass in the left nasal cavity. Computed tomography (CT) revealed a tumor extending from the left ethmoid sinus to the sphenoid sinus, and bone destruction of the anterior skull base. Magnetic resonance imaging (MRI) revealed intracranial extension of the tumor, but no apparent invasion of the brain parenchyma. Biopsy findings led to the suspicion of olfactory neuroblastoma. Since an olfactory neuroblastoma was suspected by biopsy and the possibility of invasion of the brain parenchyma was low, we performed endoscopic endonasal skull base surgery. The tumor was resected with the bone of the skull base and the dura. The skull base was reconstructed with the skull periosteum, fascia lata, and a nasal septum flap. Postoperative histopathological examination revealed the diagnosis of teratocarcinosarcoma. Therefore, after the surgery, the patient received radiotherapy. One year and ten months after the radiotherapy, metastasis to the left cervical lymph nodes was found, and neck dissection was performed. A follow-up examination at 4 years after the radiotherapy showed no evidence of local recurrence or distant metastases to other organs. It was difficult to confirm the histological diagnosis before surgery, and the diagnosis could be confirmed only by histopathology of the resected tumor specimen. The main treatment modality for teratocarcinosarcoma is surgical excision. However, teratocarcinoma is a highly malignant tumor, and radiotherapy and chemotherapy may be useful in addition to surgery, to obtain a better prognosis.

Middle ear tumors are relatively rare, and among them, the diagnoses of middle ear lesions originating from cartilage-like tissue are even rarer. Use of transcanal endoscopic ear surgery (TEES) has increased in recent years because of its advantages, such as clear visual field and minimally invasive procedure. Here, we report a middle ear mass originating from cartilage-like tissue treated with TEES. A 62-year-old woman presented with progressive right-sided hearing loss. A white mass was revealed through the tympanic membrane, and pure-tone audiometry detected a mean 50.0 dB conductive hearing loss. Computed tomography showed a mass in the tympanic cavity. TEES was performed for diagnosis and treatment. A white translucent tumor was observed intraoperatively, and it was completely resected. Histopathological examination confirmed the diagnosis of a mass originating from degenerated cartilage-like tissue. To the best of our knowledge, this is the first study of a middle ear mass originating from cartilage-like tissue treated with TEES. TEES with its clear visual field and precise techniques was beneficial in treating the middle ear lesions circumscribed in the tympanic cavity.

Conductive olfactory dysfunction (COD) is caused by an obstruction in the nasal cavity and is characterized by changeable olfaction. COD can occur even when the olfactory cleft is anatomically normal, and therefore, the cause in these cases remains unclear. Herein, we used computational fluid dynamics to examine olfactory cleft airflow with a retrospective cohort study utilizing the cone beam computed tomography scan data of COD patients. By measuring nasal–nasopharynx pressure at maximum flow, we established a cut-off value at which nasal breathing can be differentiated from combined mouth breathing in COD patients. We found that increased nasal resistance led to mouth breathing and that the velocity and flow rate in the olfactory cleft at maximum flow were significantly reduced in COD patients with nasal breathing only compared to healthy olfactory subjects. In addition, we performed a detailed analysis of common morphological abnormalities associated with concha bullosa. Our study provides novel insights into the causes of COD, and therefore, it has important implications for surgical planning of COD, sleep apnea research, assessment of adenoid hyperplasia in children, and sports respiratory physiology.

Purpose: To investigate the anatomical characteristics and clinical implications of the pterygovaginal artery (PtVA), a recurrent branch from the distal internal maxillary artery (IMA), which courses through the pterygovaginal canal that connects the pterygopalatine fossa and nasopharynx. Methods: Eighty-two patients with 90 sides of cone-beam computed tomography (CBCT) reconstructed from rotational angiography of the external or common carotid artery with a field of view covering the pterygopalatine fossa were retrospectively reviewed. The origin from the IMA, branching type, distribution, and anastomoses was evaluated. The underlying lesions were 36 hypervascular lesions with possible supply from PtVA (17 cavernous sinus arteriovenous fistulas (AVFs), 6 anterior condylar AVFs, and 13 nasopharyngeal, parasellar, or paraclival tumors) and 46 other diseases. Results: PtVA was identified in 75 sides (83%). It originated from the pterygopalatine segment of the IMA in 45 sides (60%) and from the pterygoid segment in 30 sides (40%). It arose independently (77%), sharing the common trunk with the Vidian artery (15%) or with other branches. It ran posteromedially through the pterygovaginal canal to supply the mucosa over the nasopharyngeal roof, the choanae, and the pharyngeal ostium of the eustachian tube. It anastomosed with the ascending pharyngeal artery (n=37), the accessory meningeal artery (n=7), and the mandibular artery from the petrous internal carotid artery (n=2). It served as a feeder of osseous AVFs and skull base tumors. Conclusion: PtVA was often identified by CBCT even in normal anatomy. Its detailed angio-anatomy could be evaluated in the presence of parasellar or paraclival hypervascular lesions.

Otof, which encodes otoferlin, knockout mice are considered model mice for auditory neuropathy spectrum disorder, which is characterized by an absent auditory brainstem response (ABR) despite preserved distortion product otoacoustic emission (DPOAE). Although otoferlin-deficient mice lack neurotransmitter release at the inner hair cell (IHC) synapse, it remains unclear how the Otof mutation affects spiral ganglions. Thus, we used Otof-mutant mice carrying the Otoftm1a(KOMP)Wtsi allele (Otoftm1a) and analyzed spiral ganglion neurons (SGNs) in Otoftm1a/tm1a mice by immunolabeling type Ⅰ SGNs (SGN-Ⅰ) and type II SGNs (SGN-II). We also examined apoptotic cells in SGNs. Four-week-old Otoftm1a/tm1a mice had an absent ABR but normal DPOAEs. The number of SGNs was significantly lower in Otoftm1a/tm1a mice on postnatal day 7 (P7), P14, and P28 compared with that of wild-type mice. Moreover, significantly more apoptotic SGNs were observed in Otoftm1a/tm1a mice than in wild-type mice on P7, P14, and P28. SGN-IIs were not significantly reduced in Otoftm1a/tm1a mice on P7, P14, and P28. No apoptotic SGN-IIs were observed under our experimental conditions. In summary, Otoftm1a/tm1a mice showed a reduction in SGNs accompanied by apoptosis of SGN-Ⅰs even before the onset of hearing. We speculate that the reduction in SGNs with apoptosis is a secondary defect caused by a lack of otoferlin in IHCs. Appropriate glutamatergic synaptic inputs may be important for the survival of SGNs.

Atherosclerosis is reported to be a risk factor for the severity of idiopathic sudden sensorineural hearing loss (ISSNHL). We evaluated the hypothesis that atherosclerosis affects the hearing thresholds of both the affected and healthy sides of ISSNHL patients. We conducted multivariate analyses on retrospectively collected data of patients with ISSNHL (N = 762) to evaluate the relationship between known factors linked to atherosclerosis and hearing thresholds on affected and healthy sides and whether these factors are prognostic for hearing recovery. Older ages, vertigo or dizziness, diabetes mellitus, and congestive heart failure were significantly related to higher hearing thresholds on the affected side. Older ages, male, and vascular disease were significantly related to higher hearing thresholds on the healthy side. Vertigo or dizziness, severe hearing loss and hearing loss at high frequencies on the affected side, higher hearing thresholds on the healthy side, regular anticoagulant medication, and delayed steroid treatment were significantly related to lack of recovery. Since several atherosclerosis-related factors are associated with higher hearing thresholds on both affected and healthy sides in ISSNHL and higher hearing thresholds on the healthy side predict poorer prognosis, diagnosis, and predicting prognosis of ISSNHL may benefit from rigorous evaluation of patients’ cardiovascular comorbidities and hearing levels on both the healthy and affected sides.

Objectives: Local flaps, pedicled flaps, and free flaps are used to reconstruct medium-sized skin defects after excision of parotid carcinoma. The bilobed flap is a local flap primarily used by plastic surgeons for small defects of nasal skin. We report a case of parotid carcinoma with skin infiltration successfully treated by skin reconstruction with a bilobed flap. Methods: An 84-year-old man presented with a parotid mass he had noticed 2 months earlier. Parotid carcinoma with skin infiltration was diagnosed and he underwent radical surgery. The skin defect was round (diameter, 6 cm) and was resected and reconstructed with a bilobed flap designed to be caudal to the defect. Results: Postoperative facial nerve palsy improved within 6 months. The postoperative course was otherwise uneventful, and the patient was discharged on postoperative day 7. Pathological examination revealed a sarcomatoid salivary duct carcinoma. Conclusions: Bilobed flaps are useful for reconstructing skin defects with a diameter of 6 cm or less.

Deep vein thrombosis (DVT)/pulmonary thromboembolism (PTE) is a serious condition that requires prompt and appropriate diagnosis and treatment. We report a case of head and neck surgery for a tumor in a patient with idiopathic thrombocytopenic purpura (ITP) who developed DVT/PTE and postoperative hemorrhage that were difficult to manage. The patient was a 60-year-old woman with ITP who was diagnosed as having desmoid-type fibromatosis in the head and neck region. Two days after the surgery, a decrease in blood oxygen level was detected and a chest CT was performed, which confirmed the onset of DVT/PTE, and we started the patient on anticoagulant therapy. Due to the use of anticoagulants, she developed recurrent postoperative hemorrhage which proved difficult to control. We stopped the anticoagulants and controlled the hemorrhage by applying a hemostatic agent and applying pressure to the wound. The DVT/PTE resolved, and the patient was discharged from the hospital on the 19th day after surgery. It is necessary to consider the high risk of development of DVT/PTE in cases with ITP undergoing surgery. In such cases, early diagnosis and prompt treatment are crucial. The treatment for DVT/PTE is anticoagulation, but there is a possibility that this will result in difficult-to-control postoperative hemorrhage. When postoperative hemorrhage complicates DVT/PTE treatment, careful airway management is necessary, especially in patients undergoing head and neck surgery. In patients at a high risk of developing DVT/PTE, it is important to prevent the onset of the disease, but in cases where there is a risk of hemorrhage, such as in patients with ITP, this could prove challenging. Selection of anticoagulant therapy for preventing DVT/PTE should be considered on an individual-case basis, taking into consideration the risk of hemorrhage.

Secretory carcinoma is a tumor for which the disease concept has only recently been established. Secretory carcinomas occur most frequently in the parotid gland (50%–70% of cases). They have a predilection for subjects in their 40s, and the incidence tends to be slightly higher in males. It is estimated that 10% of all salivary gland carcinomas are secretory carcinomas. The histology is similar to that of acinic cell carcinoma, and the diagnosis is often difficult to make by preoperative cytology. Detection of the ETV6-NTRK3 fusion gene plays an important role in the definitive diagnosis of secretory carcinoma. We report a case in which the fusion gene ETV6-NTRK3 was detected by preoperative cytological diagnosis. The patient was a 51-year-old man who visited our hospital with the chief complaint of a gradually enlarging mass in the right parotid region. Examination revealed a mass in the right parotid region measuring 20 mm in diameter, and fine-needle aspiration was performed. Cytological examination revealed a papillary cystic arrangement of cells that were thought to be of epithelial origin, and immunohistochemical study showed positive staining for S-100 (+), mammaglobin (focal+), CK19 (+); the ETV6 split signal was observed by FISH. Based on these findings, a preoperative diagnosis of secretory carcinoma was made, and the parotid gland lesion was treated by excision. Postoperative histopathology confirmed the diagnosis of secretory carcinoma. The detection of the fusion gene ETV6-NTRK3 by RT-PCR or FISH plays an important role as a genetic marker for diagnosing this tumor, and FISH analysis of cell block specimens, in addition to HE staining, PAS staining, and immunostaining, enabled confirmation of the diagnosis.

Surgery for vestibular schwannoma can be divided into hearing-preserving and nonhearing-preserving surgeries. Hearing-preserving surgery is usually not considered in patients with deafness due to vestibular schwannoma, because hearing is unlikely to improve, and surgery aims to maximize the tumor resection at the expense of hearing. We report an extremely rare case of a 46-year-old man with unilateral profound hearing loss due to a vestibular schwannoma with marked cystic degeneration in the left cistern, which significantly recovered to near-normal hearing levels after hearing-preserving surgery. Hearing loss gradually worsened, and preoperative pure-tone evaluation showed complete hearing loss in the left ear. However, the response to the distortion product otoacoustic emission was preserved, and hearing loss was considered to be retrocochlear. Tumor resection was performed using the retrolabyrinthine approach with continuous monitoring using dorsal cochlear nucleus action potential, auditory brainstem response, and facial nerve function muscle action potential. The cistern portion of the tumor was almost completely resected along with the wall. Postoperatively, the pure-tone threshold on the left side markedly improved. The present case clearly demonstrates the possibility of hearing recovery in patients with retrocochlear hearing loss. We should consider expanding the indications for hearing-preserving surgery.

Biphenotypic sinonasal sarcoma(BSNS) is a rare primary nasal sinus sarcoma first reported in 2012. In this report, we present a case of BSNS with skull base involvement in a 76-year-old male who underwent craniofacial surgery using a combination of craniotomy and nasal endoscopy for treatment. The tumor had extensively involved the right ethmoid sinus, and a pathological diagnosis of BSNS was made. The tumor was surgically excised in a single lump, and postoperative radiation therapy was administered. One year after surgery, no recurrent metastasis was observed. Although BSNS has a high local recurrence rate, distant metastasis has not been reported, and complete resection is crucial for disease control. For BSNS with skull base involvement, complete resection by skull base surgery combined with craniotomy and nasal endoscopy, as in this case, may be an effective option.

The DNA damage response (DDR) is an essential mechanism for maintaining genomic stability. Although DDR-targeted therapeutic strategies are being developed in several familial cancers, evaluation of their utility in head and neck squamous cell cancer (HNSCC) is lagging. This review briefly summarizes the mechanisms of DDR and the current knowledge on discovering DDR-related predictive biomarkers in HNSCC. This review also presents novel therapeutic strategies targeting DDR pathways for HNSCC based on the synthetic lethal concept. The combination of DDR inhibitors with cytotoxic treatments such as radiotherapy, chemotherapy, and immune checkpoint inhibitors is being evaluated, and several clinical trials are ongoing in patients with HNSCC. While DDR inhibitors are considered promising treatment options, resistance to these drugs is frequently observed, and their mechanisms are currently active research areas. A better understanding of the correlation between DDR pathways and cancer biology provides new therapeutic strategies for personalized medicine in HNSCC.

Highly accurate real-time cochlear nerve monitoring to preserve cochlear nerve function is essential for simultaneous cochlear implantation and ipsilateral vestibular schwannoma resection. In the present study, we developed a novel real-time monitoring system that combines dorsal cochlear nucleus action potential monitoring with intracochlear stimulating electrodes (Auditory Nerve Test System, ANTS). We used this system for a case with vestibular schwannoma resection via the translabyrinthine approach. The monitoring system developed in this study detected highly reliable evoked potentials from the cochlear nerve every two seconds continuously during tumor resection. Near-total tumor resection was achieved, and cochlear implantation was performed successfully after confirming the preservation of cochlear nerve function in a case. The patient’s hearing was well compensated by cochlear implantation after surgery. Our novel method continuously achieved real-time monitoring of the cochlear nerve every two seconds during vestibular schwannoma resection. The usefulness of this monitoring system for simultaneous tumor resection and cochlear implantation was demonstrated in the present case. The system developed in this study is compatible with continuous facial nerve monitoring. This highly accurate and novel monitoring method will broaden the number of candidates for this type of surgery in the future.

Objective: One concern for patients suffering from dysphagia is whether their swallowing improves enough to allow oral intake. Predicting oral intake independence would be practical for deciding the treatment strategy, such as swallowing improvement surgeries, at an early stage. This study describes the prognostic factors and predictive method for achieving oral intake independence at discharge from acute care hospitals. Methods: A total of 128 patients managed by the dysphagia treatment team were retrospectively examined. They were divided into two groups: the independent oral intake group and the restricted oral intake group. The patients' age, sex, causes of dysphagia, calf circumference (CC), body mass index (BMI), Hyodo score obtained through flexible endoscopic evaluation, Food Intake Level Scale (FILS) score, and Dysphasia Severity Scale (DSS) score at the initial consultation were determined. Results: The independent group had 32 patients, whereas the restricted group had 96 patients. The independent group had higher CC, BMI, and number of dysphagia cases caused by stroke. This group also had lower Hyodo scores and higher DSS scores. Multiple logistic regression analysis revealed that the Hyodo score and CC were independent prognostic factors for oral intake independence. Moreover, the prediction model developed using both factors showed relatively high accuracy (sensitivity: 42.9%, specificity: 94.0%, predictive accuracy: 81.3%). Conclusion: A lower Hyodo score and higher CC at the initial consultation may be positive prognostic factors for achieving oral intake independence. The predictive model exhibited high accuracy, indicating it may help in determining alternative treatment strategies for serious dysphagia patients. Level of Evidence: 3 Laryngoscope, 135:1661–1665, 2025.

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.

Type I spiral ganglion neurons, which play a major role in hearing by conveying electrical sound signals to the brain, are divided into electrophysiological and molecular subtypes. The differences in vulnerability among the subtypes reported in rodents are of pathophysiological importance for age-related hearing loss. However, the changes in spiral ganglion neurons in primates and humans have not been established. In this study, we investigated the age-related changes in the spiral ganglion neurons of the common marmoset, a primate model animal. Here, we show that the overall number of spiral ganglion neurons decreased in middle-aged individuals and was most pronounced during the basal turn. However, no subtype-specific reduction, as reported in rodents, was identified. Our observations indicate that aging-related changes observed in the cochlea of rodents are not always applicable to primates. The usefulness and importance of common marmosets in the study of age-related hearing loss are also highlighted.

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.