Inner ear disorders such as sensorineural hearing loss are incurable in some occasion by conventional therapeutic strategies. New therapeutic strategies for protection or recover of inner ear function are therefore to be investigated. The aim of this project is to investigate a newly-invented artificial auditory epithelium which is implantable in the inner ear. We have developed a device, which consists of a 40-micrometer-thick piezoelectric material. Piezoelectric material was fixed in a trapezoid-shape, which mimics the shape of the basilar membrane so that it will possess frequency characteristics. Pure tone was given to the prototype in the air at frequencies from 3 kHz to 20 kHz at 60 dB SPL. Oscillations of the prototype were detected and voltages produced by the prototype were measured for each electrode. The device can imitate the functions of sensory epithelia of the cochlea and transform vibratory movements into electric signals with frequency characteristics. This device can generate electrical potentials in response to sound stimuli that are able to induce auditory brain stem responses in deafened guinea pigs, indicating its capacity to mimic basilar membrane function. Artificial auditory epithelium will become an effective tool for the treatment of highly hearing-impaired patients.

We have previously shown that both Burrow’s solution (13% [v/v] acetic acid) and pure acetic acid are toxic to the inner ear. We varied the duration of drug instillation, pH, and osmotic pressure. We found that the acids penetrated the round window membrane, affecting the hair cells.

In our present report, to study the effects of acids of different molecular weights on the inner ear, we evaluated formic acid (molecular weight 46 Da), acetic acid (molecular weight 60 Da), and propionic acid (molecular weight 74 Da) in this context. After 30 minutes of instillation into the middle ear cavity, all three acids increased the compound action potential of the eighth cranial nerve. This suggests that the acids exerted toxic effects on the inner ear, regardless of molecular weight.

Model organisms are an indispensable tool for biomedical research. In order to conduct translational research that can have clinical applications, our group has been using a small non-human primate, common marmoset (Callithrix jacchus). Since whole genome database has already been established for common marmoset and novel bioengineering techniques to create genetically modified marmosets are also available, this species can be useful to establish disease models for pre-clinical research, especially for studying the genetic disorders where mouse models do not exist or for which the treatment differences among different species are known.

In this study, we performed morphological analyses of the temporal bone of marmosets. CT scan and 7-tesla MRI with or without cryogenic probe revealed that the morphology of the inner ear and ossicular chain of marmosets were similar to those of humans, although the size was relatively larger in comparison with the other surrounding structures. Mastoid air cells were replaced by a single bulla structure. These features indicate that the marmoset model is suitable for biomedical research, especially for modeling therapeutics with drug delivery into the inner ear with the post-auricular incision approach.

We report a case of external and middle ear foreign body accompanied by fracture and transection of the ear ossicles caused by a hearing aid impression material. The patient was a 65-year-old male with right chronic otitis media, who was wearing a welfare hearing aid on his left ear. Prior to the patient’s presentation at the clinic, an authorized hearing aid technician who was not part of the Japan Hearing Instruments Dispensers Association had made a sales visit to the patient’s house and had advised him to wear bilateral hearing aids at the patient’s own expense. During the visit, the technician introduced the silicone hearing aid impression material into the right ear canal.

The impression material remained in the patient’s outer ear and the middle ear, and secondary damage of the ossicular bone occurred. We removed the impression material and performed a tympanoplasty (Ⅲc) under general anesthesia. The hearing aid consultation doctor is responsible for carefully providing guidance on the subject of hearing aid fitting and use, which is included in the qualification examination of certified hearing aid technicians. It is necessary to instruct hearing aid dealers so that they do not perform medical actions such as the adaptation of hearing aids and/or the taking of ear impressions of diseased ears.

Wideband tympanometry (WBT) is a testing system that displays the acoustic energy (absorbance) of individual frequencies in the middle ear. The purpose of this study was to obtain normative data of WBT in Japanese cases, and to investigate whether the measurement of absorbance may provide improved fitting of hearing aids for patients with conductive/mixed hearing loss. The normative data were collected from 119 ears of 60 Japanese volunteers and compared with the default settings used by the manufacturer Interacoustics. Next, the absorbance data of four patients with middle ear disorders were compared with the normative data of the Japanese volunteers.

Comparison of the normative absorbance data of Interacoustics and the Japanese volunteers revealed a slight difference in sound pressure levels. For the four patients with conductive loss, the real ear insertion gain added to the absorbance value in dB was compared to the aided threshold in the sound field, and a relationship between the two was observed. These results indicate that WBT would be a useful tool when fitting hearing aids for patients with middle ear disorders.

Gradenigo’s syndrome is characterized by otitis media, trigeminal neuralgia, and paralysis of the abducens nerve. Gradenigo first reported this syndrome characterized by acute otitis media, irritation of the trigeminal nerves, and paralysis of the abducens nerve in 1904. Here, we report the case of a 51-year-old man with severe diabetes mellitus who was referred to the local hospital due to left otalgia. The patient was given oral antibiotics after he was diagnosed with acute otitis media. However, the patient did not respond to treatment. Three weeks later, he complained of trigeminal neuralgia and paralysis of the abducens nerve. He was then referred by the local hospital to our hospital. Computed tomography revealed right mastoiditis and no intradural or brain lesion. There was no evidence of petrous apicitis. However, magnetic resonance imaging revealed a lesion in the left petrous apex that had low density on T1-weighted images, high density on T2-weighted images, and high density on diffusion-weighted images. The patient was diagnosed with Gradenigo syndrome’s, for which he underwent ventilation tube insertion during hospitalization. He was started on intravenous ceftriaxone at 4 g/day, combined with hydrocortisone at 1 g/day to improve dura edema. The patient responded to conservative treatment with broad-spectrum antibiotics and intensive insulin therapy. Therefore, surgery was not performed. After treatment, otorrhea and temporal pain quickly diminished. Paralysis of the abducens nerve resolved completely after 3 months. He was discharged on day 10 of hospitalization. He has been attending our out-patient clinic for regular check-ups for 6 months, with no apparent symptoms.

Mucopolysaccharidoses (MPS) include a spectrum of disorders characterized by the genetic deficiency of specific lysosomal enzymes. MPS occurs in as many as 1 in 60, 000 people in Japan and is classified into seven subtypes, according to the defective lysosomal enzyme. MPS is a progressive disease that involves the accumulation of glycosaminoglycans within cells throughout the body. The head and neck manifestations of this disease include recurrent otitis media, hearing loss, and upper airway obstruction. Curative treatment involves enzyme replacement therapy (ERT) and hematopoietic cell transplantation (HCT). A retrospective chart review of 31 patients with MPS, referred by the Pediatrics Department at our hospital between April 2005 and March 2016, was performed. The average age of the patient at the first audiometry examination, was 12. 1 years (range: 1-53 years). We recorded the patients’ hearing level, type of hearing loss, and whether or not the MPS was complicated by otitis media. For the 26 patients who underwent follow-up audiometry for over 3 years (follow-up period: 3-27 years), we evaluated the differences between the results of the first and last audiometry examinations, as well as the effect of ERT and HCT on their hearing. During their first audiometry examinations, 44% of the patients exhibited mixed hearing loss and 45% exhibited moderate hearing loss. Among the patients who underwent follow-up audiometry examinations, 42% exhibited progressive hearing loss, whereas 19% showed an improvement in their hearing loss. HCT tended to prevent the progression of hearing loss in patients with MPS. It has been reported that HCT has a curative effect on MPS I and II, when administered before the progression of the disease. The evaluation of MPS patients by otolaryngologists is essential for early recognition and initiation of treatment.

Patients with acoustic tumors sometimes recognize a sudden difficulty in hearing. Therefore, it is important to distinguish an acoustic tumor from sudden hearing loss.

We developed a clinical pathway that includes treating a patient with sudden hearing loss with an intravenous infusion of steroids and PGE1 for 1 week. The pathway includes an evaluation of the inner ear for an acoustic tumor using magnetic resonance imaging (MRI). We found 12 cases of acoustic tumors by screening MRI examinations in 730 cases of sudden sensorineural hearing loss over 15 years.

We introduced all the cases to a neurosurgeon. Eight patients were placed under observation and 4 patients underwent surgery. The average of the size of tumor was 11. 6 mm. The size of the tumor was less than 5 mm in 4 cases and greater than 2 cm in 4 cases.

We classified these cases as 1 of 2 types based on the tumor’s position. The tumor appeared at the internal acoustic meatus in 5 cases and invaded the post-cranial fossa in 7 cases.

The audiogram of cases of acoustic tumors sometimes show a so-called “Valley type” pattern. We reclassified the patterns based on the hearing differences when compared to the hearing in the contralateral ear, in order to remove the influence of presbycusis. The reclassified audiograms of 3 cases presented a “Valley type” pattern while 3 cases showed deaf pattern in 12 cases. A diagnosis of acoustic tumor based only on the audiogram pattern is difficult.

When sudden hearing loss is suspected, it is imperative to start treatment rapidly. We found that an early evaluation of the inner ear to find an acoustic tumor during treatment using MRI is significant.

Superior canal dehiscence syndrome (SCDS) is caused by thinness of the bone over the superior canal, or other acquired factors such as trauma or cerebrospinal pressure.

A 71-year-old-man presented with pulsatile tinnitus and momentary faintness induced by sound (Tullio phenomenon). High-resolution computed tomography scans of the temporal bone revealed a tubular defect of the right superior canal, which was the superior petrosal sinus enlarged by a dural arteriovenous fistula (dAVF). After endovascular treatment, momentary faintness was easily induced by both sound and pressure due to the exposure of the bony dehiscence to the intracranial space.

We concluded that traumatic dAVF-induced hyper shunt flow and vascular pressure of the transverse-sigmoid sinus and superior petrosal sinus caused the dehiscence of the superior canal. AVF has good reason to cause acquired and unilateral high pressure of the upper part of the superior canal. This case suggests the possibility of a new etiology of SCDS.

CHARGE syndrome is a congenital disorder associated with multiple malformations resulting from abnormal embryonic organogenesis. Sensory disorders such as vision and hearing impairments, are associated with significant developmental delay in patients with CHARGE syndrome. Therefore, congenital deafness is treated through cochlear implantation. However, deafness is often diagnosed and managed after treatments for a wide variety of complications in patients with CHARGE syndrome. In addition, it is extremely difficult to perform surgery for deafness owing to the presence of various malformations in the ear region in these patients. Here we present our results of cochlear implantation performed in 2 patients with CHARGE syndrome. Detailed preoperative assessment of anatomical indicators and development of a plan for safely performing cochlear implantation are considered important.