The field of otorhinolaryngology covers the ear, nose, oral cavity, pharynx, larynx, trachea, esophagus, and neck. Each organ is composed of various tissues, such as bone, cartilage, muscle, connective tissue, mucosa, vessels and nerves.

Many of the cells show constant cell loss due to cell death, and homeostasis is maintained by the supply from tissue stem cells, which is thought to contribute to the repair and regeneration of tissues when damaged.

Tissue stem cells are multipotent cells with the ability for self-renewal, and can differentiate into multiple types of cells that constitute a tissue.

While research on tissue stem cells began with hematopoietic stem cells, stem cells from various organs have been identified, such as those from the skin, intestine and neural tissue. In regard to the environment that maintains tissue stem cells, a special microenvironment termed the “niche” exists within each tissue that allows the cell number and undifferentiated state of stem cells to be maintained.

This paper will attempt to provide a basic knowledge of stem cells and tissue stem cells, the available experimental methods such as organoid and cell lineage-tracing for stem cell identification, the major tissue stem cells, and tissue stem cell research in the field of otorhinolaryngology.

Introduction: A clinical pathway for hospitalization of patients with acute vertigo at the Department of Otolaryngology was developed. Patients for whom this clinical pathway was used were patients with acute vertigo in whom causes of dangerous vertigo, such as a cerebral infarction, were excluded, patients in whom the vertigo symptoms lasted for more than a few hours, and patients who wanted to be hospitalized. The clinical pathway was designed to be used not only by otorhinolaryngologists, but also by doctors on emergency duty on holidays and at night, without consulting an otorhinolaryngologist. The purpose of this study was to evaluate the effects of introduction of the clinical pathway on the hospitalization dynamics and medical staffs.

Methods: In this retrospective study, the subjects were patients who were hospitalized at the Department of Otolaryngology for follow-up of acute vertigo during the year before and after the introduction of the clinical pathway.

Results: After the introduction of the pathway, the number of patients hospitalized increased by 2.3 times, hospitalizations from the emergency room increased significantly, and the rate of patients with vertigo of unknown origin was significantly higher as compared with the case before the introduction of the clinical pathway. Introduction of the clinical pathway reduced the burden by defining clear indications for hospitalization and allowing doctors on emergency duty to hospitalize patients quickly, reducing nursing work in the emergency room and the work of nurses in nursing planning at the time of hospitalization, and reducing the number of on-call nights and holidays for otorhinolaryngologists.

Conclusion: Although the number of patients with vertigo of unknown origin increased, the introduction of this clinical pathway reduced the burden on the medical staff, and was useful for hospital management.

One-and-a-half syndrome is a horizontal ocular movement disorder characterized by a conjugate horizontal gaze palsy in one direction and ipsilateral internuclear ophthalmoplegia, with usually preserved convergence. The responsible lesion is in the dorsal pontine tegmentum, and magnetic resonance imaging (MRI) is often used to diagnose the syndrome. It is often caused by unilateral cerebral infarction in elderly patients. We report a case of one-and-a-half syndrome in which the responsible lesions of the brainstem could not be visualized on MRI.

The patient was a 68-year-old man who presented with the complaints of dizziness and diplopia. Horizontal and vertical ocular movement disorders were observed. The right eye was fixed at the midline for all lateral movements, and the left eye could only abduct and exhibited left-beating nystagmus. Paresis of both the eyes was observed during upward gazing. In addition, convergence was impaired. Magnetic resonance angiography (MRA) on the day after admission showed narrowing of the bilateral vertebral arteries, suggestive of severe stenoses. However, we could not visualize any high signal intensity areas in the brainstem on diffusion-weighted image (DWI) MRI of the brain. MRA on the seventh day after admission showed re-perfusion of the vertebral arteries on both sides. DWI MRI revealed a high signal intensity area in the left cerebellar hemisphere fed by the anterior inferior cerebellar artery, but no high signal intensity area in the brainstem. Based on the abnormalities of horizontal monocular eye movements observed on electronystagmography and a history of atrial fibrillation, we diagnosed multiple microinfarcts in the brainstem, including in the paramedian pontine reticular formation and ipsilateral medial longitudinal fasciculus. In this case, we needed to assess eye movements over time before a diagnosis could be made, because brain microinfarction is sometimes difficult to diagnose by imaging.

Introduction: Inner ear hemorrhage can manifest with symptoms such as dizziness, deafness, and tinnitus, and can be diagnosed by MRI, but it is relatively rare and the diagnosis may be overlooked.

Case: A 76-year-old male. The patient had suffered from a sensation of light-headedness for some time, but a year ago, he also developed vertigo and right hearing loss that occurred during head position changes. Findings of a head contrast MRI examination suggested widespread right inner ear hemorrhage. The patient had a previous history of diffuse idiopathic osteoproliferative disorder and rheumatoid arthritis. No nystagmus was observed during gaze, electronystagmography showed alternating directional nystagmus, a caloric test revealed semicircular canal paralysis, cVEMP was unresponsive to the right, and oVEMP was decreased to the right. The vertigo gradually improved during follow-up, and the findings of right inner ear hemorrhage on the MRI disappeared after 2 months. A standard pure tone audiometry showed improvement in hearing in the right bass range, and the nystagmus changed to directional (horizontal to the left) nystagmus. Improvement was observed in the center of gravity sway test, but the caloric test results as well as the cVEMP and oVEMP remained unchanged with a decrease to the right.

Conclusion: We encountered a case of vertigo/deafness, in which inner ear hemorrhage was tentatively diagnosed by MRI evaluation. The main symptoms were dizziness and moderate sensorineural hearing loss, but the symptoms improved with the disappearance of the lesion that appeared to be hemorrhage in the inner ear. However, the vestibular function test results remained abnormal. The course of the test results suggest, that the greater the degree of hemorrhage, the greater the degree of disability.

We report two cases of glomus tympanicum tumor, which were classified as type III and II tumors according to the Glasscock-Jackson classification. Before surgery, interventional radiology-CT (IVR-CT) angiography and 3D image reconstruction was performed to obtain detailed information about the feeding vessels and also the inflow sites into the tumor. Based on the obtained information, management for bleeding was deemed to be necessary in both cases. Therefore, we attempted to use temporary blood flow blockade of the external carotid artery during the surgery, which resulted in a significant decrease of the blood flow. Thereafter, en bloc resection was performed in both cases.

Objective tinnitus is defined as ringing in the ears that can be heard by both the individual and another person. Diverse movements of the muscles, such as of the soft palate, eardrum, and facial muscles occur when tinnitus occurs. We previously reported in this journal that even though there is a diversity of muscle movements, the pathology is often the same, namely, patulous Eustachian tubes. In this report, we report our analysis of additional seven cases (in addition to the cases included in our previous report) of objective tinnitus synchronized with the opening and closing of the Eustachian tube. As in this report, two cases had a patulous Eustachian tube, whereas no patulous Eustachian tube was observed in the remaining five cases. In these five cases, the patients had become habituated to objective tinnitus since childhood. This habit is called “habitual clicking” and the pathologies caused by this habit were examined.

It is assumed that “habitual clicking” causes overworking of the muscles, since the Eustachian tube opens and closes more voluntarily than usual. It is thought that the muscles may be stressed, overstrained, or easily convulsive. Therefore, involuntary tinnitus can occur and become the chief complaint. In patients with dizziness, hyperacusis and high-pitched tinnitus as chief complaints, the eardrum can be moved voluntarily, and similarities with tonic tensor tympani syndrome were observed. If tonic tensor tympani syndrome was also caused by Eustachian tube disorder, that would be a new finding. Further accumulation of cases seems necessary to prove this. Treatment aimed at ceasing the habit is desired.

Osteonevus of Nanta is a nevus-cell nevus associated with osteomas, that accounts for 5.6% of case of nevus-cell nevus; it commonly occurs on the face. The frequency of nevus-cell nevus is particularly high in the case of auditory canal tumors, however, to the best of our knowledge, there are no reports of external auditory canal osteonevus of Nanta. Herein, we report a case of external auditory canal osteonevus of Nanta. The patient was a 70s woman who presented with an 8-mm elastic-hard tumor in the external auditory canal. This tumor showed a high density on CT. Thus, osteonevus of Nanta should be included in the differential diagnosis in patients who present with a hyperdense tumor in the external auditory canal on CT.

Traumatic cerebrospinal fluid (CSF) leakage is reported to occur in 1%–3% cases of severe head injury. New onset cases could be improved by conservative management, while surgical treatment is recommended for late-onset and recurrent cases. Herein, we report a case of recurrent CSF leakage that developed 22 years after head injury, which was successfully closed by an intracranial and transsphenoidal approach. A 57-year-old-man had been diagnosed as having traumatic CSF leakage 22 years earlier, and treated by surgery. Since then, he had had no recurrence of symptoms. However, he visited us with a history of watery nasal discharge and was diagnosed as having recurrence of CSF leakage. Computed tomography showed a 20 mm-sized bone defect in the sphenoid sinus, suggesting CSF leakage through the bony defect. We performed craniotomy to close the defect of the sphenoid sinus with artificial dura mater and the fascia of the tensor fasciae latae muscle. The fistula was then closed with an artificial dura mater using the transsphenoidal sinus approach and the sphenoid sinus was filled with fat. After the operation, no recurrence of the CSF leakage was observed. Transcranial and transnasal endoscopic surgery was useful for closure of a large fistula in the deep skull base.

Patulous eustachian tubes are associated with symptoms such as aural fullness, and voice and breath autophony, which are very distressing symptoms for patients. Many patients with a patulous eustachian tube are also reported as being mentally unstable. We conducted a questionnaire survey to clarify the psychological profiles of patients with patulous eustachian tubes, and report the results with a review of the literature. A total of 103 patients who visited our outpatient clinic were assessed by the Self-rating Depression Scale (SDS) and the State-Trait Anxiety Inventory (STAI). The median scores at the initial diagnosis were PHI10 26 (20–32), SDS 45 (39–55), STAI state anxiety 50 (43–57), and trait anxiety 48 (44–56). The Spearman’s rank correlation coefficient for PHI10 and SDS was 0.457 (p value 0.00161), that for PHI10 and STAI state anxiety was 0.457 (p value 0.00143), and that for PHI10 and characteristic anxiety was 0.487 (p value 0.000608), all representing significant correlations. The PHI10 improved in 73.1% of the 26 patients who required follow-up visits after the treatment. On the other hand, there was no statistically significant difference in the change of the PHI10 between the group of patients with very severe depression and those with STAI characteristic anxiety on SDS. The subjective symptoms were significantly improved with lower SDS values. There have been several reports on the relationship between a patulous eustachian tube and anxiety and depressive tendencies. The present study suggests that patients with high levels of depression and trait anxiety may be resistant to treatment and may have difficulty in receiving the usual treatments, suggesting the need for considering the psychological aspects of the disease.

We present a case of sigmoid sinus thrombosis that developed during chemoradiotherapy for locally advanced external auditory squamous cell carcinoma. The 78-year-old female patient underwent chemoradiotherapy (TPF-RT) for T3 left external auditory squamous cell carcinoma. She developed transit ischemic attack-like symptoms on day 30 of treatment. MRI revealed left sigmoid sinus thrombosis. Although thrombus formation predicted by irradiation has been reported, sigmoid sinus thrombosis is rare. It is important to check for D-dimer levels and perform MRI in patients who develop transit ischemic attack-like symptoms during CRT.

Otorhinolaryngologists often treat infections presenting with the chief complaints of fever, sore throat, and cervical lymphadenopathy, but they rarely include collagen diseases in the initial differential diagnosis. Adult-onset Still’s disease is a condition that is difficult to diagnose, as there are few specific laboratory findings, and it is a typical example of a disease that manifests as fever of unknown origin. We encountered a case of adult-onset Still’s disease in which the patient presents with cervical lymphadenopathy, followed by fever of unknown origin and systemic symptoms, making it difficult to make an accurate diagnosis. A 40-year-old woman visited an otorhinolaryngologist with painful cervical lymphadenopathy. She was diagnosed as having cervical lymphadenitis and prescribed an antibiotic, but was referred to our department when she failed to improve. At the first visit, the patient had no fever, and the throat findings were unclear. However, during follow-up, she developed a rash with fever, followed gradually by easy fatigability, and was hospitalized. Blood tests showed liver dysfunction, increased inflammatory response marker levels, and a mild increase in the serum level of ferritin. Infections and malignant tumors were considered unlikely, and cervical lymph node biopsy proved non-diagnostic. Remittent fever was noted during hospitalization, and joint pains appeared. A dermatologist consultation led to the suspicion of adult-onset Still’s disease, the diagnostic criteria for adult-onset Still’s disease were met, and the skin biopsy results were in agreement. Although it is necessary to make a diagnosis of fever of unknown origin immediately, it is important to carefully carry out a process of diagnosis by exclusion in cooperation with other departments, while keeping in mind the possibility of adult-onset Still’s disease in patients presenting with cervical lymphadenopathy.

Transoral surgery (TOS) is a less invasive surgery and is becoming the major approach for the treatment of laryngo-pharyngeal tumors. Although several types of laryngoscopes are available for TOS, the tongue base is still one of the most difficult parts in which to obtain appropriate surgical views. We developed an adapter to connect an Arm Controller to the Macintosh laryngoscope for resection of a tumor at the tongue base. The adapter allowed us to obtain appropriate surgical views and operate smoothly without the need to use other special instruments or causing stress to the surgeons.

Persistent postural-perceptual dizziness (PPPD) is a chronic dizziness disorder that is newly listed in the WHO International classification of diseases, ICD-11, revised in 2018. In this study, I selected definite cases of the first occurrence of benign paroxysmal positional vertigo (BPPV) among vertigo patients who visited our clinic in the past two years, and retrospectively reviewed the age at the first visit, gender, affected side, previous medical conditions, type of BPPV, and their tendency toward transition to PPPD.

Eligible subjects were new first-ever cases of BPPV who visited our clinic during the one-year period from June 1, 2020 to May 31, 2021, and who met the diagnostic criteria for BPPV established by the Japan Society for Equilibrium Research.

There were 311 cases, including 120 men and 191 women, with a male: female ratio of 1:1.6, hence the majority of case were women.

The mean age ± standard deviation was 60.7 ± 17.8 years. Men ranged in age from 14 to 88 years, with a mean age of 64.2 ± 16.3 years. Women ranged in age from 11 to 90 years, with a mean age of 58.5 ± 18.5 years. Thus, the average age of the men was higher.

As for the type of BPPV, there were 172 cases of posterior semicircular canal-type BPPV (canalolithiasis), 79 cases of lateral semicircular canal-type BPPV (canalolithiasis), and 60 cases of lateral semicircular canal-type BPPV (cupulolithiasis), with the posterior semicircular canal-type BPPV (canalolithiasis) being the most common.

In regard to the affected side, the right side was affected in 164 cases and the left side in 147 case; thus, involvement of the right side was more common.

The time to remission was less than 0.5 month in 86 cases, less than 1 month in 69 cases, less than 2 months in 50 cases, less than 3 months in 22 cases, and more than 3 months in 57 cases. Remission was achieved in less than 3 months in 72.9% of cases. The course remained unknown in 27 case, as the patients discontinued their clinic visits.

There was only one case of a 75-year-old man and one case of a 70-year-old woman who transitioned to PPPD. Both cases had left-sided posterior semicircular canal-type BPPV (canalolithiasis). The man had underlying hypertension, while the woman had underlying hypertension and diabetes mellitus.

The rate of transition from BPPV to PPPD was 0.6% when cases with an unknown course were included, and the rate was as low as 0.7% when cases with an unknown course were excluded. Thus, the frequency of transition from BPPV to PPPD is low.