Vestibular schwannoma (VS), commonly known as acoustic neuroma, is a tumor arising from the Schwann cells of the vestibular nerve. Its primary symptoms include sensorineural hearing loss, tinnitus, and vertigo. With the aging population, the number of affected patients is increasing. However, the mechanisms underlying tumor-induced hearing loss, as well as the tumor’s development and progression remain unclear. This study aimed to elucidate the mechanisms of hearing loss caused by VS and to develop novel diagnostic and therapeutic strategies. Using cultured cells from resected tumors, it was demonstrated that microRNAs contained within extracellular vesicles can induce damage to the auditory nerve. Additionally, the inhibitory effects of various compounds on tumor growth were investigated, and candidate biomarkers that correlated with tumor size and hearing levels were identified. VS is not a rare disease, and in numerous cases, neither surgery nor radiation therapy is recommended. Instead, patients are managed through a “wait and scan” approach. As specialists in hearing and balance disorders, otologists play a pivotal role in the management of this disease, and are committed to advancing research efforts in this field.

Detailed preoperative assessment of local findings is the key to successful otological surgery. This article discusses the key assessment points for the auricle, external auditory canal, tympanic membrane, and middle ear, which are important in otological surgeries.

It is important to understand the proper positioning for observation of the tympanic membrane, differences in its appearance between children and adults, and selection of an otoscope. Additionally, this article explains the condition of the pars flaccida and pars tensa of the tympanic membrane, anomalies of the ossicles, and the differential diagnosis of middle ear lesions.

Even under the same conditions, the complexity of surgery can vary. Therefore, it is important to accurately predict the pathology based on local findings and formulate a preoperative plan according to the level of expertise.

We hope that this article will serve as a helpful guide for the accurate assessment of preoperative conditions.

Pure-tone audiometry is often performed preoperatively, because the presence or absence of conductive hearing loss is a critical factor in determining the indications for middle ear surgery. However, the audiometric profile serves as an important finding that reflects the pathological conditions of the middle ear, including the tympanic membrane and ossicular chain. Therefore, it must be thoroughly evaluated in conjunction with imaging studies, such as temporal bone computed tomography (CT), preoperatively to ensure a safe and appropriately targeted procedure.

In interpreting pure-tone audiometry, it is essential to have a fundamental understanding of masking concepts and verify that threshold determination has been performed appropriately. Additionally, in cases in which multiple pathological conditions coexist, certain conditions that may not be visualized on CT can manifest as audiometric findings. Careful interpretation of these findings can contribute to more precise and effective middle ear surgery.

Whether it is microscopic or endoscopic ear surgery, understanding temporal bone anatomy and diagnostic imaging is essential for performing surgery. High-resolution computed tomography (CT) of the middle ear and inner ear is required. First, it is important to understand the representation of normal structures on CT images. The next step is to check for irregular structures such as inner ear malformations, ossicular malformations, abnormal facial nerve trajectories, internal auditory canal stenosis, and an enlarged vestibular aqueduct. Then, soft tissue shadows, ossicular destruction, calcification, demineralization, skull base, and inner ear bone damage are assessed. Magnetic resonance imaging (MRI) is useful for qualitatively evaluating soft tissue shadows on CT, evaluating the auditory and facial nerves, and assessing the condition of the membranous labyrinth of the inner ear. MRI is not required for all otologic surgeries, but it may be used when needed to determine the appropriate surgical strategy. Diagnostic imaging skills can be improved by reviewing postoperative images.

Basic outpatient treatment of external and middle ear conditions is common in otorhinolaryngology. These treatments are often performed under a microscope, necessitating proper training to execute the procedures under microscopic visualization.

If performing outpatient treatment, it is essential to develop an image-filing system using an endoscope and implement infection preventive measures through medical instruments. Therefore, infection risks and medical safety are of paramount importance.

The lecture focuses on four external ear conditions commonly encountered in outpatient settings (earwax blockage, cholesteatoma, mycosis of the external ear canal, and epithelial pearl) and describes treatment approaches for each condition.

The treatment of external and middle ear conditions is a fundamental procedure in otorhinolaryngology outpatient practice. Accurate diagnosis and appropriate management are important patients with otorrhea. Through proper diagnosis and treatment, early improvement can be achieved; however, this may be impossible with drug administration alone.

This procedure requires microscopy or endoscopy and careful manipulation of surgical instruments under a microscope. For patients with otorrhea, basic treatments, including culture examination, cleaning, aspiration, wiping, and management of granulation tissue, should be performed before administering the appropriate medications. Because the underlying lesions causing otorrhea vary depending on the disease, the ear canal, tympanic membrane, and tympanic cavity must be closely observed through the tympanic perforation after cleaning the otorrhea.

Postoperatively, important structures, such as the ossicles, lateral semicircular canal, and facial nerve, may be exposed, necessitating meticulous handling. Outpatient procedures enable otologists to refine their skills and it is crucial to ensure that these procedures are performed safely and effectively.

Aminoglycoside antibiotics, cisplatin, loop diuretics, and salicylic acid are representative drugs that induce hearing loss. These drugs are administered systemically for treatment or symptom relief of various diseases; however, they may cause sensorineural hearing loss. Hearing loss caused by systemic drug administration is generally bilateral sensorineural. Although hearing loss caused by aminoglycosides and cisplatin often presents as irreversible, loop diuretics and salicylic acid cause reversible hearing loss. This article provides an overview of drug-induced hearing loss caused by systemic drug administration and describes the site of action of each drug in the inner ear, typical course of hearing loss, and approach for prevention and treatment.

Cochlear implantation (CI) is a feasible treatment for severe-to-profound hearing loss, with criteria varying by country. In Japan, CI candidates must have an average pure-tone hearing level of ≥90 dBHL, or 70–90 dBHL with maximum aided monosyllable recognition <50%. However, many countries usually refer to the speech perception score at the sound pressure level of a typical conversation (65 dBSPL). Among the 111 cases (135 ears) of severe hearing loss, this study measured the number of cases that met the current Japanese criteria and those of other countries. Consequently, applying the new criteria increased eligibility from 50% to 79%. Our findings can serve as a reference for revising CI criteria in Japan.

Here, we report a case of surgical resection and cochlear implantation (CI) for early-stage external auditory canal cancer in the only hearing ear that achieved tumor control and good auditory function. The patient previously underwent open ear surgery for right-sided deafness and presented with left otorrhea. A tumor was observed in the external auditory canal, and biopsy revealed squamous cell carcinoma. The patient was diagnosed with Pittsburgh-T2 external auditory canal cancer. Provided the severe hearing loss in the only hearing ear, we performed simultaneous lateral temporal bone resection and cochlear implantation. Adjuvant radiotherapy was administered because the deep margins of the lateral external auditory canal were positive. Eight months postoperatively, FDG uptake on FDG-PET/CT raised the suspicion of local recurrence. Consequently, concurrent tumor resection and cochlear implant replacement were performed. The postoperative speech discrimination ability with the cochlear implant was favorable. There was no change in the aided thresholds compared to the initial surgery. This approach provides high curability and good postoperative auditory function in cases of external auditory canal cancer in only hearing ear with severe hearing loss.

Localized amyloidosis is a disease in which amyloids are deposited in certain organs, leading to organ damage. Head and neck localized amyloidosis is rare, whereas nasopharyngeal amyloidosis is extremely rare. Here, we describe the case of nasopharyngeal amyloidosis in a 36-year-old woman who presented with otitis media and effusion. The patient had a medical history of laryngeal amyloidosis 13 years previously. Because of the viscous effusion in the bilateral middle ears and pathological findings of the nasopharyngeal lesion, the patient was diagnosed with nasopharyngeal amyloidosis. Systemic amyloidosis and multiple myeloma complications were ruled out, and the patient was observed without any treatment. Therefore, nasopharyngeal amyloidosis should be considered in patients with persistent otitis media and effusion. Furthermore, the pharyngeal orifice of the eustachian tube should be carefully examined, and any abnormalities should be subjected to imaging and histological examination.

Intralabyrinthine schwannoma (ILS) is a rare benign tumor. Here, we report a case suspected of ILS for which multiple vHIT and VEMP tests were performed, revealing vestibular function deterioration. A 52-year-old woman presented with dizziness and left-sided hearing loss that did not improve with initial treatment. ILS was suspected on magnetic resonance imaging, and she was referred to our hospital. At the first visit, vHIT showed decreased function in the left posterior semicircular canal. However, VEMP did not reveal any abnormalities in the otolith organs. After one year, vHIT showed decreased function in all three semicircular canals, and VEMP revealed abnormalities in the otolith organs. Over the following two years, vHIT and VEMP results progressively worsened. There are few reports of vHIT and VEMP applied to ILS cases domestically and internationally, and no reports have followed cases gradually. As more cases like this are studied with vHIT and VEMP, we believe that it may help in understanding the pathogenesis and pathophysiology of ILS.