In this study, we investigated whether the difficulty and intraoperative complications of cochlear implant surgery can be estimated from temporal bone HRCT imaging findings, and conducted basic research on the understanding of cochlear nerve pathophysiology using ECAP. We found that the intraoperative view of the round window niche was affected by the angle between the external auditory canal and the basal turn of the cochlea and the positional relationship between the basal turn of the cochlea and the facial nerve. Intraoperative CSF Gusher was found to be more likely to occur in cases with no modiolus, large vestibular aqueduct diameter, and a short inner ear canal, while postoperative facial nerve stimulation was more likely to occur in cases with a short inner ear canal length and a small vestibular aqueduct diameter. In cases with ossification of the cochlea after meningitis, the normal cochlear CT value of less than 200 HU was found to become more than 500 HU. ECAP measurements showed that there were cases in which short latency action potentials could be recorded with the distant recording electrode, while examination of current spread revealed that the nerve groups being measured were identical.

Excessive amounts of ototoxic agents, such as cisplatin and aminoglycoside antibiotics, usually induce hair cell death and permanent sensorineural hearing loss. They generate reactive oxygen species (ROS) in the cochlea, which activate several kinase pathways, including c-Jun-N-terminal kinase, p38 mitogen-activated protein kinase, and protein kinase B (AKT). These kinase pathways function as damaging or protecting mechanisms in ototoxicity. Sphingolipid metabolites, including ceramide, sphingosine, and their phosphorylates (ceramide-1-phosphonate [C1P] and sphingosine-1-phosphate [S1P]), are well-known regulators of diverse cellular processes, including apoptosis, cell cycle, and cellular differentiation. This review summarizes the roles of sphingolipid mediators in cochlear ototoxicity.

Two pathways are known to generate ceramide: the de novo ceramide synthetic pathway and the sphingomyelinase pathway (ceramide/sphingomyelin cycle). Ototoxic agents activate sphingomyelinase, and ceramide is mainly generated via activated sphingomyelinase in the cochlea through a ceramide/sphingomyelin cycle from sphingomyelin. The generated ceramide is converted to other sphingolipid mediators. Ceramide and sphingosine accelerate the cochlear hair cell death induced by ototoxic agents. Conversely, C1P and S1P inhibit cochlear hair cell death. S1P receptor subtype 2 is involved in the hair-cell protection effect of S1P. C1P and S1P activate AKT, which inhibits the cochlear hair cell death induced by ototoxic agents.

In conclusion, sphingolipid mediators are generated in response to ototoxic agents and play important roles in determining the fate of cochlear hair cells in ototoxic injury.

Cartilage conduction hearing aids (CCHAs) are available in clinical practices and have rapidly spread in Japan. However, knowledge of their indication and limitation are not fully clarified because of the introduction of a new device. A survey on the fitting of the CCHA found high purchase rates (approximately 80%) in 256 cases with atretic ear or chronic otorrhea who hardly benefited from air conduction hearing aids. The findings demonstrated that these cases are good indications of CCHAs. In order to establish the audiological indication of CCHAs, their output levels were evaluated according to the standard methods used in air and bone conduction hearing aids. The results suggested that audiological benefits are sufficient in cases with mild or moderate hearing loss in open ears and with bone conduction hearing levels better than 20–40 dB in the closed ears. The transmission mechanism of cartilage conduction is different from those of air and bone conductions. Furthermore, the ear condition can affect the transmission of cartilage conduction. Thus, the benefits of CCHAs have to be actually evaluated after fitting the device for precise understanding.

Although causes of vertigo or dizziness vary widely across medical specialties, peripheral vertigo due to inner ear and vestibular nerve disorders accounts for a majority of these cases. Thus, otolaryngologists often receive referrals for patients with dizziness from other departments. To address this, otolaryngologists need to meet the expectations of patients and medical professionals by providing accurate diagnoses and treatments for dizziness.

Recently, information and communication technology (ICT) has become universal due to the widespread use of smartphones and tablet devices and the development of data communication technology. As such, medical support applications and devices based on smartphones and tablet devices are being developed to promote dizziness treatments and improve regional consultation capabilities. Based on the medical support applications and devices we have developed and advanced case studies from different countries, we were able to draw the image of telemedicine and online medical care and discuss the advantages of online medical care for patients and physicians in dizziness treatment, including its ability to overcome barriers for widespread use.

The Japan Otological Society (JOS) conducted a nationwide epidemiological survey of patients with middle ear cholesteatoma who underwent initial surgery in 2015, enrolling 1,787 patients at 74 facilities in Japan. In 2018, a follow-up survey was conducted on 1,456 cases at 49 facilities in Japan, with 1,060 cases examined for hearing prognosis and 1,084 cases examined for recidivism prognosis. The hearing improvement rate was 63.3%, and 152 patients (14.0%) were found to have a recidivism. In 2020, the JOS compiled terminologies related to tympanoplasty, which further detailed its optional procedures. Moreover, members of the JOS and others also examined the extent to which optional procedures are performed for each condition and surgery.

In this issue, a comparative study of the epidemiology, surgical procedure selection, optional procedures, and outcomes in pars flaccid cholesteatoma and pars tense cholesteatoma was conducted.

In the future, surgical procedure selection and the use of optional procedures will become more standardized depending on the degree of staging. In addition, the issues and prospects of middle ear cholesteatoma treatment in the near future will also be discussed.

Vestibular evoked myogenic potential (VEMP) has been established as a functional assessment for the otolith organs. VEMP includes cervical VEMP—which is recorded in the ipsilateral sternocleidomastoid muscle to examine saccular function—and ocular VEMP—which is recorded just below the contralateral eyeball to examine utricular function. VEMPs have revealed some new findings. One finding is that the solo otolithic disorders cause sensation of linear motion on the plane where the macula is placed. In other words, the saccular and utricular lesions cause linear motion on the sagittal and horizontal planes, respectively. In addition, although the positional vertigo of benign paroxysmal positional vertigo disappears following positional therapies, such as Epley’s maneuver, some patients experience persistent dizziness even after successful treatment with positional therapy. The residual dizziness is related to the persistent utricular disfunction. It is interesting to note that these new findings are consistent with previously known physiologic facts. To date, VEMP is one of the essential examinations for a comprehensive study of vestibular function.

Recent issues in a super-aged society result in the increasing demand for fall-prevention strategies. To achieve this goal, we conducted research to quantify unsteadiness. Since otolithic and visual/proprioceptive inputs are integrated to sense gravity and construct a reference frame, we intended to quantify the otolith-ocular reflex to evaluate the risk of fall, detect high-risk individuals, and suggest preventive medical interventions. This reflex can be estimated in a roll plane using ocular counter-rolling. The gain of otolith-ocular reflex in a roll plane can further be calculated by the ratio of the angles of ocular counter-rolling to that of head inclination. On the other hand, estimation in a pitch plane requires calculation of the Listing’s plane. In addition, the ratio of the tilting angle of Listing’s plane to the head inclination angle can indicate the gain of the reflex. Herein, we outline our previous studies and introduce our future research.

First, we revealed the typical characteristics of Listing’s plane in healthy subjects as a parameter for evaluating otolith function. Next, we verified the pathological modification of Listing’s plane in various vestibular deficits, since vestibular dysfunction thickens the plane and reduces the precision of the otolith-ocular reflex. Furthermore, optokinetic-induced pseudo-disturbance of gravitational input was also revealed to thicken Listing’s plane, indicating the possibility that Listing’s plane can reflect, not only peripheral otolith function, but gravity recognition as well. Simultaneously, we are establishing a mouse model of this otolith-ocular reflex to enable invasive experiments. For the precise calculation of Listing’s plane, we clarified the characteristics of the torsional saccade, which demonstrates the torsional main sequence with saturating characteristics, similar to that of the horizontal and vertical aspects. Additionally, we are conducting research to elucidate the existence of a static cervical-ocular reflex to compensate for the otolith-ocular reflex. Since we are trying to disclose the mechanism of unsteadiness after rotational and caloric stimulation, we are instituting a program using virtual reality goggles to increase the accuracy of measurements and develop a system of precise evaluation and rehabilitation.

This study aimed to clarify the mechanism of hearing loss caused by an increase in endolymphatic pressure using a human cochlear finite-element model. An increase in the endolymphatic pressure caused by the endolymph hydrops (EH) was simulated by loading a static pressure on the surface of the basilar membrane (BM) of the model. When the static pressure was loaded, initial deformation of the apical side of the BM was noted, and the middle part of the BM was deformed with a further increase in the magnitude of static pressure. The vibration of the BM by applying sound pressure was calculated in the model under static pressure and compared with that in the normal cochlea. The envelope of the BM vibration in the normal model shows a spindle shape. Whereas under static pressure, an elongated spindle shape was obtained. As a result, the vibration amplitude of the BM was decreased, and the characteristic frequency (CF) distribution was changed. Alteration in hearing levels caused by loading a static pressure was approximately estimated from the ratio of vibration amplitude obtained from the EH model to that from the normal model at the CF point of the normal model. The amplitude of the vibration of the BM reduced with the increase of the static pressure applied to the BM. Changes in the CF distribution and the envelope of the BM vibration might influence frequency discrimination ability. These changes might cause a fluctuating hearing loss associated with a change in the endolymphatic pressure.

CHARGE syndrome is characterized by a combination of congenital abnormalities. These patients usually have anomalies of the temporal bone, such as venous malformations, inner and middle ear malformations, and aberrant facial nerves. Cochlear implantation in CHARGE syndrome cases is technically challenging because of these malformations. Image-guided surgery systems (IGSSs) should be helpful intraoperative tools for malformations encountered in patients with CHARGE syndrome. Herein, we report two cases of cochlear implantation supported with IGSS in children with CHARGE syndrome. We used bone-anchored fiducial markers to maximize the accuracy of IGSS. Computed tomography (CT) images were taken with fiducial markers after initiating operations using a mobile cone-beam CT; these images were used to register the IGSS. This method allowed the preoperative preparations to be skipped and increase the accuracy of IGSS. In both cases, IGSS helped us to perform mastoidectomy safely and determine the site of cochleostomy despite cochlear malformation (cochlear hypoplasia type III), aplasia of semicircular canals, high jugular bulbs, protrusion of the sigmoid sinus, a remnant of the petrosquamosal sinus, and aberrant route of the facial nerve. We report our registration method for IGSS and the usefulness of our technique.

We report about a 6-year-old boy with transient facial paralysis that occurred after prophylactic inner ear obliteration. The patient had unilateral deafness owing to an abnormality in the inner ear, incomplete partition (IP-I).

As the risk for meningitis in IP-I was high, preventive inner ear obliteration was performed. During the surgery, a bony defect of the stapedial footplate and leakage of the cerebrospinal fluid were noticed. Therefore, after removing the stapedial footplate, inner ear obliteration with the temporal muscle fascia and cartilage was performed. The patient developed facial paralysis after surgery and underwent a second surgery the next day. The fascia and cartilage in the inner ear were removed, and re-obliteration was performed. We first inserted the cartilage into the inner ear and filled the fascia above it, which is the reverse order of the procedure in the first surgery. Subsequently, the facial nerve paralysis improved, and no cerebrospinal fluid leakage or meningitis was observed. Facial nerve paralysis was considered to occur because of nerve compression in the internal auditory meatus by obliteration materials.

Although there are few reports of neuropathy owing to inner ear obliteration, it is necessary to devise methods to prevent excessive nerve compression in the internal auditory meatus.

We report a case of postoperative conductive hearing loss due to an osseous lesion around the stapes following facial nerve decompression. A 46-year-old, male patient with severe peripheral facial nerve palsy underwent transmastoid decompression of the facial nerve. Postoperatively, an audiogram showed conductive hearing loss of approximately 30 dB. Six months later, the patient underwent an exploratory tympanotomy, which demonstrated limited improvement in his hearing. He visited Mitsui Memorial Hospital for consultation 13 months postoperatively and underwent a reoperation.

There was no lesion around the incus although it was dislocated and had been repositioned at the first operation; however, an osseous lesion around the stapes to the promontory was found.

The stapes could move smoothly after laser ablation of the osseous fixation, and his hearing level improved to approximately 16 dB. In this case, the osseous lesion around the stapes was considered to have formed with bone dust remaining in the tympanic cavity during the facial nerve decompression operation combined with the fibrin glue used at the time of ossicular chain reconstruction. In conclusion, we should take care to wash out bone residue sufficiently in facial nerve decompression.

Middle ear myoclonus (MEM) is a rare diagnosis of tinnitus that is presumed secondary to abnormal stapedius or tensor tympani muscle movement. Herein, we describe four cases of MEM with no history of facial palsy. We speculate that tinnitus was caused by tensor tympani muscle contraction, as visible eardrum movement was observed in all four cases. In case 1, eardrum movement was synchronized with forced eyelid closure, which was diagnosed as forceful eyelid closure syndrome. In cases 2, 3, and 4, rhythmic eardrum movement was observed, while putting strength into the ear. In cases 1 and 2, muscular tinnitus became tolerable after behavioral therapy, and the patients declined further treatment, such as medical therapy and surgical tenotomy of the tensor tympani. Thorough history-taking, otoendoscopic examination, and stapedial reflex testing during eye blinking, or putting strength into the ear are recommended when encountering middle ear muscular tinnitus.

We report a case of giant trigeminal schwannoma with ear symptoms such as mixed hearing loss, dizziness, and tinnitus. A 34-year-old woman had been treated for otitis media with effusion at an ENT clinic for about 2 years. She was referred to our hospital because of left ear tinnitus and progressive hearing loss. Close inspection of the head and neck region and examination of blood tests ruled out the presence of nasopharyngeal tumor, eosinophilic otitis media, and otitis media with ANCA-associated vasculitis. Because the patient showed mixed hearing loss, gadolinium-enhanced MRI was finally conducted to rule out cerebellopontine angle lesions. Consequently, a huge tumor was found in the middle cranial fossa. The legion was an extradural tumor that extended to the internal auditory canal (IAC), compressing the vestibulocochlear nerve. The anatomical location of the tumor and clinical symptoms suggested trigeminal schwannoma as the most probable pathology.

In this patient, otitis media with effusion was suggested due to compression of the Eustachian tube by the tumor, and hearing loss, dizziness, and tinnitus were due to compression of the vestibulocochlear nerve at IAC. Finally surgical excision of the tumor was performed, and the pathology was confirmed as a meningioma.

Traumatic perilymphatic fistulas are caused by direct external forces, such as head or middle ear trauma, or indirect external forces, such as pressure trauma. Perilymphatic fistulas are rarely associated with pneumolabyrinth, which may affect hearing and worsen prognosis. We report a case of a patient with a traumatic perilymphatic fistula with pneumocephalus in the internal auditory meatus. A 15-year-old male presented with a chief complaint of vertigo and left-sided hearing loss. During baseball practice, the left side of his head had been hit by a ball. He had horizontal dextrorotatory mixed nystagmus. Pure-tone audiometry showed left ear scale-out. Computed tomography showed pneumolabyrinth and pneumocephalus in the internal auditory meatus, suggesting a left traumatic perilymphatic fistula. There were no fracture lines in the temporal bone or otic capsule, and no middle or inner ear malformations were observed. Emergency fistula closure was performed. During the operation, a floating footplate was noted. Continuous perilymph leakage was observed from the oval window. Despite repairing the stapes and attempting to seal the footplate borders with fascial tissue grafts, the leakage was difficult to control. Therefore, to close the fistula, the stapes was removed, the oval window sealed with fascial tissue grafts, and the stapes was returned to the fascia to restore the ossicular chain. Postoperatively, the vertigo improved immediately but hearing did not. A possible explanation for the pneumocephalus in the internal auditory meatus is the penetration of air bubbles through minute gaps in the bottom of the internal auditory meatus, associated with the floating footplate caused by intense trauma.

Subannular tube (SAT) insertion was introduced as a method for extending the length of time that middle ear intubation can remain in place before tube replacement is needed and for reducing the risk of tympanic membrane perforation after extubation. Although the rate of complications such as tympanic membrane perforation after extubation has been low with SAT insertion, in some cases, the time that the SAT could remain in situ has not been as long as expected compared with that of the transtympanic T-tube insertion.

We performed cartilage myringoplasty combined with SAT insertion in four pediatric patients who had tympanic membrane adhesion and atelectasis or persistent perforation after extubation. Herein, we report this series of pediatric cases treated at our department.

In these four patients, the SAT remained in place for 580–695 days after intubation with no complications, excluding one case in which the tube was unintentionally extruded. This is a longer period than that observed in cases of SAT insertion without a cartilage graft at our department.

SAT insertion combined with cartilage myringoplasty could be the treatment of choice to avoid the risk of perforation inherent with the long-term placement of a transtympanic T-tube.

Amyloidosis of the external auditory canal is often differentially diagnosed as mass lesions of the ear canal and has been reported in several cases; however, it is rare and not widely known.

This is a case report of a 70-year-old woman who presented at her first visit with multiple small skin nodules were observed on the skin of the external auditory canal, on both sides. The pathological findings included subepithelial acidophilic non-structural material and a red-orange color on Dylon staining, which led to the diagnosis of amyloidosis of the external auditory canals. Subsequent systemic assessment revealed no other lesions, and we concluded that the patient had cutaneous amyloidosis confined to the external auditory canal. No specific treatment was administered, and regular ear cleaning and follow-up were performed. The tumors have been decreasing in size but have not disappeared.

In dermatology, amyloid is often deposited in regions that encounter friction by the long-term use of nylon towels and brushes. Furthermore, chronic mechanical stimulation, such as habitual ear picking, may be involved in the origin of external auditory canal amyloidosis, as in this case.