In Japan, a super-aging society, maintaining healthy longevity without age-related dysfunction is a major concern. Age-related hearing loss is one of the most common age-related functional disabilities, but methods to prevent the progression of hearing loss have not yet been established. Recently, it has become clear that immune aging is involved in the aging system. The immune system becomes dysfunctional with aging, and the decline in the function of immune cells results in the accumulation of oxidative and inflammatory compounds that should otherwise be processed by inflammatory response. The accumulation of these wastes results in prolonged and chronic inflammation. Furthermore, age-related chronic inflammation induces persistent oxidative stress. This vicious cycle of immune aging, chronic inflammation, and oxidative stress has recently been termed oxi-inflamm-aging. In fact, it has been reported that the inoculation of bone marrow cells and splenocytes from young mice and the provision of naïve T cells can prevent age-related hearing loss. Based on these findings, we investigated the mechanism of age-related hearing loss and its clinical application for prevention.

Ramsay Hunt Syndrome (RHS) is a major factor causing the impaired quality of life of patients due to severe facial paralysis, so more effective treatments are desired. To overcome RHS, it is important to (1) enable early diagnosis and early treatment, (2) develop a new antiviral treatment and (3) prevent its onset. Early diagnosis is essential to begin treatment at an early stage; however, it is difficult to distinguish RHS from Bell’s palsy at the first visit, particularly in atypical cases without a skin vesicle, called “zoster sine herpete”. It is also desirable to educate the public to visit an otolaryngologist promptly, so that patients with facial paralysis can receive the appropriate treatment. For RHS, the zoster vaccine is expected to suppress its incidence and reduce complications. Zoster vaccines are not yet well known in Japan and is hoped to have a more widespread use in the near future.

In 2019, the Japanese Society of Otolaryngology created the iCI2004, the “Word Tone Listening Assessment Test for Artificial Hearing Devices”. This test consisted of a monosyllable test and a word test. The word test is expected to have a better response rate than the monosyllable test because it provides a logical complement to the word test. In this study, the correct response rates for the monosyllable and word tests were compared in cochlear implant cases. The results showed that the adult group had an average of 52.1% for the monosyllable test and 72.8% for the word test, while the pediatric group had an average of 57.2% for the monosyllable test and 80.1% for the word test, with a significant difference between groups. The difference in performance between the two tests was approximately 20%. The percentage of correct responses for the monosyllable and word tests was not significantly different between the adult, child, and word test only groups (p > 0.05). In addition, the test could be administered at younger ages with a word test rather than a monosyllable test. If the subject is younger, there may be situations in which the monosyllable test is difficult to perform. Even in such cases, there are cases where word tests can be performed. Based on the above, we expect that the word test will be actively used.

In the Nucleus^®24 Cochlear Implant users, we investigated why channel deactivations in the Distal division (apical side of the cochlea) significantly reduced Japanese speech recognition ability.

Each Japanese consonant consists of a preceding consonant and a following vowel. Therefore, data of consonant recognitions obtained in the 67S speech audiometric test were analyzed by dividing them into preceding consonants and following vowels. Deactivation of continuous seven channels in the Distal division significantly decreased recognition both of preceding consonants and following vowels compared to other divisions, and had substantial effects on following vowels.

The first and second formant information (F1, F2) are the most important in determining vowel recognitions. Therefore, using the sound spectrogram and formant analysis, we measured F1 and F2 frequencies of following vowels and investigated the channels where F1 and F2 were input in the experimental maps. We found that the channel deactivations of the Distal division shifted the input location of both F1 and F2 to the base of the cochlea, which distorted the frequency information and caused a significant drop in performance.

Considering the channel deactivations site as “cochlear dead regions,” it was suggested that the damage of hair cells and auditory nerves in the cochlear apical side is more likely to result in losses and distortions of vowel frequency information than in the cochlear basal side and cause more damage to the hearing in Japanese.

Among recently developed electrode arrays, slim modiolar electrode arrays are prone to folding within the cochlea, a condition known as tip fold-over. One of the mechanisms that cause tip fold-over is the misalignment between the electrode array’s coiling direction and the cochlea’s curving direction. Thus, surgeons should be careful during slim modiolar electrode insertion and align the coiling planes of the electrode array and the cochlea. However, successful alignment of the electrode array’s coiling direction and the cochlea’s curving direction largely depends on the surgeon’s imagination. We recommended preoperative three-dimensional simulation to determine the correct coiling plane of the cochlea. However, not all surgeons are familiar with preoperative simulations using computers. Therefore, we developed a method of determining the coiling plane of the cochlea using anatomical landmarks that can be visualized during cochlear implantation.

We retrospectively investigated preoperative CT data of 65 ears of patients who underwent cochlear implantation by one surgeon during the period of 2017–2021. Revision cases and inner ear anomaly cases were excluded. The preoperative CT dataset was three-dimensionally reconstructed. A plane was defined containing short and long processes of the incus, as “plane of the incus”. The angle between the plane of the incus and the coiling plane of the cochlea (incudocochlear angle) were measured and collected. The incudocochlear angle was averaged at 34.6 degrees. No statistical differences were noted between the left and right ears. No statistical differences were noted in terms of age at surgery. The 95% confidence interval of the angle was 23.4–45.7 degrees. Thus, once the incus is visualized during surgery, it is possible to correctly determine the coiling plane of the cochlea. This simple method does not require the surgeon’s ability of computer simulation and may help prevent misalignment and subsequent electrode tip fold-over.

Tip fold-over occurred in 4 out of 62 cases in which the slim modiolar electrodes (CI532/632) were inserted. Herein, we investigated the electrode insertion route, the tip fold-over frequency, the surgical technique, and its factors.

The electrode insertion route consisted of cochleostomy in 0 ears (0%), a round window approach in 48 ears (64%), and an extended round window approach in 27 ears (36%). Tip fold-over occurred in 4 ears (5.3%). Three of the four cases with tip fold-over were handled by the round window approach and one by the extended round window approach.

In four of our cases of tip fold-over, the round window membrane was not sufficiently visualized and it was suspected that the tip was caught at the time of insertion. This suggested that the sheath may have contacted the cochlear window entrance and have been inserted with the electrode escaping from the sheath.

Therefore, it is necessary to secure an adequate view when inserting the sheath using the round window approach. If it is difficult to achieve clear vision, the extended round window approach should be chosen to ensure that the sheath is correctly inserted into the round window.

If the tip gets caught, the sheath should be pulled out once to make sure that the electrode has not escaped from the sheath.

Sonotubometry is commonly used for the qualitative (yes/no) detection of active Eustachian tube (ET) opening during swallowing. This study was designed to evaluate whether the external auditory canal sound amplitude (ESA) and duration of ET opening (DETO) of sonotubometry have quantitative information about ET structural patency. Fifty-seven ears with tympanic membrane perforation and 53 contralateral ears without perforation from 55 patients (male:female, 26:29; mean age, 47 years) were included in this study. A commercially available clinical equipment (JK-05A, RION Co., Japan) was used to record the following: the input sound pressure (ISP) level of sonotubometry, ESA, and DETO; ET opening pressure with Valsalva maneuver (VP); and passive opening pressure (POP) with the passage test, which quantitatively measures passive and structural patency of ET. POP was not recorded in 53 years without tympanic membrane perforation, as the test needs perforation. With the VP, 43% of ears did not appropriately complete the maneuver due to the complex task of the maneuver. With the passage test, normal, stenotic, and patulous ETs were found in 70%, 28%, and 2% of ears, respectively. There are statistical correlations between ESA and DETO in tympanic membrane with (r = 0.88; 95% CI, 0.80–0.93; p < 0.0001) and without perforation (r = 0.93; 95% CI, 0.87–0.96; p < 0.0001). ESA (r = –0.50; 95% CI, –0.68– –0.27; p < 0.0001) and DETO (r = –0.46; 95% CI, –0.65– –0.21; p = 0.0004) were significantly correlated with POP. ISP did not correlate with POP (p = 0.21), while VP was correlated with POP (r = 0.37; 95% CI, 0.043–0.62; p = 0.024). The area under the ROC curve (AUC) suggested that ESA (AUC = 0.78; 95% CI, 0.65–0.92; p = 0.0010) and DETO (AUC = 0.78; 95% CI, 0.64–0.92; p = 0.0011) can predict ET patency. For the diagnostic test for stenotic ET, the ESA cut-off value was set at 8 dB by the Youden index, and the stenotic ET on sonotubometry also had a high risk of stenosis of structural patency with an odds ratio of 19.1 (95% CI, 4.2–89.7). Ninety-four percent of non-stenotic ears on sonotubometry were also non-stenotic on structural patency. This study demonstrated that ESA and DETO have quantitative information about the passive ET function.

In the case of a traumatic perilymphatic fistula, the patient profile, the type of surgery to be performed, and the timing of surgery should be considered. Herein, we report a case of a traumatic perilymphatic fistula in which the left ear was injured by a cotton swab, resulting in hearing loss and dizziness, which improved after stapes surgery. Upon initial examination, the patient had a perforated left tympanic membrane and spontaneous nystagmus. A computed tomography scan revealed a dislocation of the incudomalleal joint and emphysema in the vestibule. As the patient had conductive hearing loss but no elevated bone-conduction threshold, the initial treatment included the administration of antibiotics and corticosteroids. Concurrently the patient was put on bed rest. On the 8th day since the incident, the dizziness resolved. However, an elevation of the bone-conduction threshold developed. Hence, the surgery was performed. The incus was removed, followed by the stapes because the entire footplate had been dislocated. The air trapped in the emphysematous vestibule was replaced with saline. The oval window was covered with subcutaneous connective tissue, a malleus attachment piston was placed on it, and the tympanic membrane perforation was closed underlay. Postoperatively, the hearing improved, and the dizziness and nystagmus disappeared. Traumatic perilymphatic fistulas require appropriate decision-making regarding the timing and surgical technique.

Elongated styloid process can cause various symptoms of discomfort in the laryngopharynx and neck due to overgrowth of the styloid process and ossification of the stylohyoid ligament.

We encountered an extremely rare case of facial nerve palsy that was most likely caused by an elongated styloid process and successfully treated with surgery.

A 30-year-old man presented with a chief complaint of right lower ear pain during swallowing, and computed tomography (CT) showed bilateral elongated styloid processes. Right facial nerve palsy developed a day after the initial visit, and tapered steroid therapy was started on Day 7 of facial palsy onset.

Based on the regional diagnosis and previous reports, the causal site of the right peripheral facial nerve palsy was thought to be peripheral to the bifurcation of the tympanic nerve between the stylomastoid foramen and the base of the styloid process. On Day 13 of onset, the facial nerve score was 8/40 and electroneuronography result was 0%; therefore, facial nerve decompression and styloidectomy were performed.

At 14 months postoperatively, the patient’s facial nerve score was 40/40, and the facial nerve palsy was completely cured. Additionally, the right low ear pain on swallowing had disappeared.

Thus, based on this case and previous reports of elongated styloid process with peripheral facial nerve palsy, facial nerve decompression in addition to styloidectomy can be considered useful for treating facial nerve palsy.