The cochlear implant of electric-acoustic stimulation (EAS) has proved to be useful for patients with ski-slope-type hearing loss. Despite less traumatic surgery and use of flexible electrodes, there remains great inter-individual variation in hearing preservation (HP) rate. The present paper focuses on various predictive factors, including surgical approach, electrode design, electrode length, insertion depth angle, insertion speed, use of steroids, age at implantation, cochlear duct length (CDL) and volume, and etiology of hearing loss. Together with our data from patients receiving EAS (44 patients, 50 ears, from 41 families), we studied to clarify which factors may affect the individual HP rate.

For surgical procedure, the round window approach has proved to be less traumatic and is currently recognized as the standard surgical approach for EAS. Further, the use of a flexible straight array has revealed to be beneficial for HP. Moreover, systemic and/or topical steroid usage pre-, intra-, and post-operatively is recommended as a standard protocol for EAS to protect the cochlea from surgical trauma.

In contrast, electrode length, insertion depth angle, insertion speed, age at implantation, and cochlear duct length (CDL) remain somewhat controversial issues. According to our results, HP was correlated with age at implantation, which is consistent with previous reports, while HP was independent of pre-operative average of low-frequency hearing thresholds, and individual CDL. In our cohort study, no significant differences in HP were observed among the three types of electrode length (24 mm, 28 mm, and 31.5 mm), indicating that HP did not depend on electrode length. The natural course of hearing change should be considered in patients with residual hearing. Most of EAS candidates have progressive hearing loss, full insertion of medium/long electrodes is considered to be the best solution to compensate for the future hearing deterioration at the lower frequencies. Our recent data indicated that HP can be achieved with longer electrodes, and the addition of acoustic stimulation appears to improve total hearing ability. Currently, in order to increase the preservation rate of residual hearing, intraoperative monitoring cochlear microphonics is performed.

Genetic testing identified the cause of hearing loss approximately in half of the patients. We found that patients who had pathogenic variants in the CDH23, MYO7A, or MYO15A gene, expressing in the inner and outer hair cells, showed statistically better HP scores compared with patients with hearing loss due to other causes. Genetic testing can facilitate the accurate diagnosis of EAS candidates as well as the prediction of residual hearing after EAS.

Superior semicircular canal dehiscence syndrome (SCDS) is first reported by Minor in 1998 and has been debated and reported about therapies, especially surgical methods. One of them is the reinforcement method of round window which is based on the “third window theory” and seems reasonable but sometimes it was not effective very well. On the other hand, the dehiscence of most SCDS cases is identified directly by using the methods of plugging and resurfacing with middle cranial fossa (MCF) approach, but it is hard to observe it when it locates underneath superior petrosal sinus (SPS). Furthermore, there are always risks of adverse events such as brain damages when the MCF approach is chosen, so it is not easy to decide surgery owing to this dilemma. Therefore, the plugging of the dehiscence with the transmastoid approach has been advocated to perform easier to otosurgeons than MCF approach. Controversially the dehiscence is hardly observed from the low side and it is likely to say that there is more risk of sensory neural hearing impairment than the other approaches.

To dissolve these problems, we modified the plugging technique with transmastoid approach safer by using underwater endoscopic technique. It became possible to observe the membranous canal and the area of dehiscence very clearly by using this technique of soaking the tip of an endoscope underwater when superior semicircular canal is to be opened after mastoidectomy. Even if the dehiscence located on SPS, this technique is advantageous in safety and feasibility by approaching from underneath. The setting of this technique, adaptations, and the postoperative results will be demonstrated.

New developments have been seen in both the diagnosis and treatment of patulous Eustachian tube, and it is an urgent task to grasp the actual situation. Therefore, a questionnaire survey was conducted for medical education institutions and Japanese Otologic Society delegates. The diagnostic criteria proposed by Japan Otological Society was used by 76.5%, and about half of the institutes were found to use JK05-A models as Eustachian tube function test apparatus. For conservative treatment, lifestyle guidance, Chinese herbal medicine administration, and nasal instillation of physiological saline were adopted at many facilities. There were 581.7 intractable cases per year resistant to conservative treatment. As surgical treatments, ventilation tube insertion and silicone plug insertion have been performed frequently. Based on the results of this questionnaire survey, it seemed necessary that the use of Eustachian tube function tests should further be promoted, and that the proper use of the surgical treatment for the patulous Eustachian tube should also be promoted in the future.

The malleus bar indicates the bony bar that connects the bony tympanic ring and the malleus, first reported in 1988 by Nomura et al. A 9-year-old girl was referred to our hospital for adenoid hyperplasia and suspected sleep apnea syndrome. Hearing loss was suspected in the patient based on the findings of the right ear and history obtained at the first outpatient visit. Thus, pure tone audiometry and tympanometry were performed. The pure tone hearing average on the affected side was 51.7 dBHL and on the left side was 15.0 dBHL, with a maximum air-bone gap of 40 dB on the affected side. The tympanogram of the right side was type C, whereas the left side was type A. Computed tomography revealed a high-density structure extending backward from the malleus. Therefore, an exploratory tympanotomy and transcanal endoscopic ear surgery was planned for the possible detection of the malleus bar. Malleus bar and ossicular chain dysfunction were detected during the surgery; therefore, we performed the tympanoplasty IIIi-M. The postoperative pure tone hearing average of the affected side improved to 18.3 dBHL. According to previous reports, a possibility for better hearing improvement was observed in patients who underwent ossiculoplasty along with the removal of the malleus bar. Therefore, transcanal endoscopic ear surgery can be considered useful for the treatment of malleus bar.

A 75-year-old woman, who presented with right-sided otalgia and occlusion of the right ear canal, was referred to our hospital. The patient underwent ear surgery three times for cholesteatoma otitis media. Temporal bone computed tomography showed a wide soft-tissue shadow occupying the right tympanic cavity, mastoid bone, and ear canal, and bone destruction was observed in the posterior wall of ear canal and middle cranial fossa. The regions covered by the shadow displayed high-intensity signals on diffusion-weighted magnetic resonance imaging, which led to the diagnosis of recurrent cholesteatoma otitis media. At her first visit to our hospital, no ear discharge, facial palsy, or dizziness was observed. An audiological examination revealed mixed hearing loss.

Mastoidectomy was performed in the patient via the transcortical approach. Cholesteatoma occupied the mastoid and tympanic cavities. When we tried to remove the cholesteatoma matrix from the dura mater, cerebrospinal fluid (CSF) leakage occurred. It is likely because at the middle cranial fossa, the dura mater had thinned due to pressure from the cholesteatoma in the mastoid cavity. After the cholesteatoma was thoroughly removed, the resultant bone and dural defects were reconstructed with cartilage with fascial, connective, and adipose tissue. Continuous CSF drainage via a lumbar subarachnoid catheter was performed postoperatively. On the 7th postoperative day, the lumbar catheter was removed. The next day, the patient developed high fever, nausea, and headache. She was diagnosed with bacterial meningitis based on CSF examination. According to the Practical Guidelines for Bacterial Meningitis, 2014, meropenem, vancomycin, and gentamicin were administered as empiric antibiotics. Subsequently, Enterococcus faecalis was detected in blood and CSF cultures. Thereafter, we administered ampicillin, and discontinued meropenem and vancomycin. Antibiotics were administered for bacterial meningitis for 30 days. The spinal drain was removed on the 32nd postoperative day. Fortunately, the patient was discharged without any severe sequelae.

CSF leakage during cholesteatoma surgery can cause life-threatening complications. Although ear surgeons rarely encounter CSF leakage during operations, they must know how to manage this issue.

Middle ear adenoma is a rare disease. There are only a few reports on this disease in Japan. It is classified as a middle ear carcinoid/neuroendocrine tumor and a synonymous disease according to the WHO middle ear tumor tissue classification (2005). The frequency of local recurrence and cervical lymph node metastasis is reported as 22% and 14%, respectively, in the long term; hence, it is considered a low-grade malignant tumor.

The patient complained of tinnitus and hearing loss. There was a tumor lesion in the external ear canal. Computed tomography/magnetic resonance imaging showed a faintly enhanced mass in the tympanic chamber. Pathological examination showed an epithelial tumor with luminal formation, and almost no nuclear atypia or fission image was observed. Epithelial and neuroendocrine markers were positive on immunohistochemistry; therefore, a diagnosis of middle ear adenoma was made. We performed tympanoplasty for total tumor resection. The tumor was located mainly in the middle and the lower tympanic cavity and had spread to the facial fossa, tympanic sinus, and the vicinity of the round window. We completely resected the tumor, and the patient was disease free up to three years after surgery. Middle ear adenomas may recur or metastasize after more than 10 years; hence, long-term follow-up is required.

Mitochondrial dysfunction is considered to be associated with aging and age-related hearing loss, and mitochondrial transfer RNA (mt-tRNA) deficiency is one of the causes of mitochondrial dysfunction. Herein, we performed metabolome analysis to investigate the metabolic changes associated with cochlear senescence as a result of mt-tRNA deficiency. Metabolites, which are related to aerobic metabolism, accumulate in aged mice with mitochondrial dysfunction. Our results suggest that mitochondrial damage in the cochlea of aged mice accelerates their senescence, thereby causing age-related hearing loss.

Magnetic resonance imaging (MRI) can potentially induce sensorineural hearing loss (SNHL); therefore, noise protection is crucial. Few studies have explored this topic. We recently encountered three older patients with acute onset of noise-induced hearing loss after undergoing 3.0 T MRI. In one patient, hearing loss occurred in the better ear and two of these three patients experienced SNHL. During MRI, all three patients used either earplugs or earmuffs. Thus, using earplugs or earmuffs alone is insufficient; so both must be used. We recommend that (quieter) 1.5 T MRI should be preferred over the (louder) 3.0 T MRI whenever 1.5 T MRI is diagnostically adequate.

We report a case of psychogenic hearing loss initially suspected as labyrinthine concussion. A 32-year-old woman received left-sided head trauma during work. She suffered from left-sided hearing loss immediately after injury and visited our department 6 days later. Initially, labyrinthine concussion was suspected as the underlying cause of horizontal sensorineural hearing loss, with the patient having an average hearing level of 51.3 dB. However, her hearing level subsequently deteriorated to 87.0 dB, and an audiogram showed mixed hearing loss. In addition, psychogenic hearing loss was suspected because her hearing ability was satisfactorily improved with a hearing aid, despite severe hearing loss. Therefore, an auditory brainstem response (ABR) test was performed. Since ABRs were normal, she was diagnosed with psychogenic hearing loss. Upon her return to work, about six months after injury, her hearing ability returned to normal the following day. Therefore, fear of going to the workplace where the trauma occurred may have caused psychogenic hearing loss. Thus, psychogenic hearing loss should also be considered in a differential diagnosis for hearing loss, even in the presence of head trauma.