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Middle ear implants (MEIs) such as the Vibrant Soundbridge (VSB) are attractive and alternative treatments for patients with conductive, sensorineural, and mixed hearing loss who do not benefit from, or who choose not to wear, conventional hearing aids (HAs). Recent studies suggest that MEIs can provide better improvements in functional gain, speech perception, and quality of life than HAs, although there are certain risks associated with the surgery which should be taken into consideration, including facial nerve or chorda tympanic nerve damage, dysfunctions of the middle and inner ears, and future device failure/explantation. In Japan, a multi-center clinical trial of VSB was conducted between 2011-2014. A round window vibroplasty via the transmastoid approach was adopted in the protocol. The bony lip overhanging the round window membrane (RWM) was extensively but very carefully drilled to introduce the Floating Mass Transducer (FMT). Perichondrium sheets were used to stabilize the FMT onto the RWM. According to the audiological criteria, the upper limit of bone conduction should be 45 dB, 50 dB, and 65 dB from 500 Hz to 4, 000 Hz. Twenty-five patients underwent the surgery so far at 13 different medical centers. The age at the surgery was between 26-79 years old, and there were 15 males and 10 females. The cause of conductive or mixed hearing loss was middle ear diseases in 23 cases and congenital aural atresia in two cases. The data concerning on the effectiveness and safety of VSB was collected before the surgery and 20 weeks after the surgery. Significant improvements of free-field Pure Tone Audiogram (PTA) from 250 Hz to 8, 000 Hz were confirmed (p < 0.001). Hearing gain up to 40 dB was achieved in the 1, 000 Hz to 4, 000 Hz range. No deterioration in either air conduction or bone conduction at PTA was noted at 20 weeks after the surgery. Monosyllable speech perception in both quiet and noisy conditions improved significantly (p < 0.001). The speech discrimination score in both quiet and noisy conditions improved significantly too (p < 0.001). In the future, it is likely that there will be an increasing population even in Japan that will meet the criteria for MEIs such as VSB. However, the long-term efficacy and safety of these devices should be established.

The Vibrant Soundbridge (VSB) is an active middle ear implant with the Floating Mass Transducer (FMT). We performed a multicenter study to study the efficacy of the VSB by means of "the 10 Questionnaire on Hearing 2002" and "the APHAB questionnaire" at 13 hospitals between 2011 and 2013. In all, 23 patients with mixed or conductive hearing loss received VSB implantation by the round window placement technique. These individuals were generally unable to use, or gained little from conventional hearing aids or bone conduction hearing aids. Two questionnaires were administrated before the surgery and 20 weeks after the VSB implantation. Scores on every item of "the 10 Questionnaire on Hearing 2002" showed significant improvement under noise after VSB implantation. On the APHAB, the scores for Ease of Communication, Reverberation, and Background subscales improved significantly after the VSB implantation, while the score for the Aversiveness subscale alone failed to show a positive improvement from the inexperience to the new sound. Analysis of the responses to these subjective questionnaires revealed better results after VSB implantation as compared to the preoperative data. In conclusion, RW vibroplasty with the use of VSB provided subjective benefit in patients with conductive and mixed hearing loss.

Usher syndrome is an autosomal-recessive disorder that causes bilateral sensorineural hearing loss, retinitis pigmentosa (RP), and occasionally vestibular dysfunction. Usher syndrome types 1, 2, and 3 can be distinguished by differences in audiovestibular features. The objectives of this retrospective study were to evaluate 26 patients with Usher syndrome clinically. The 26 patients (male: 12 cases, female: 14 cases) with Usher syndrome, with a clinical diagnosis based on symptoms of bilateral sensorineural hearing loss and RP, had been registered from 13 hospitals as a multicenter study. We assessed the clinical history and performed audiovestibular and ophthalmologic examinations, and genetic testing. Eleven of the patients were classified as having Usher type 1 (38.5%), 6 with Usher type 2 (23.1%), and 9 with Usher type 3 (38.5%). However, many patients with atypical Usher type 1 (70%) and type 2 (83.3%) were found compared with Usher type 3 (10%). The conductive rate of vestibular examinations including the caloric test (50%) was low. There were many variations in the clinical symptoms in Usher syndrome patients, therefore the classification of Usher types 1, 2, and 3 has been complicated. We have proposed a flowchart for the diagnosis of Usher types 1, 2, and 3.

The effectiveness of bone anchored hearing aid (BAHA) for the patients with congenital aural atresia was evaluated by multicenter clinical study in Japan. Twenty patients (17 bilateral and 3 hemilateral) of congenital auricular atresia were registered for this study and finally, 18 of them (15 bilateral and 3 unilateral) were subjected to further evaluation. Primary endpoint of this study was free sound-field pure-tone audiometory and speech threshold hearing test in quiet and noisy circumstances. Secondary endpoint of this study was patient's satisfaction based upon APHAB (Abbreviated Profile of Hearing Aid Benefit) questionnaire survey. These results were compared between before and 12 weeks after BAHA surgery. Both hearing level of pure tone and speech threshold significantly improved after BAHA surgery. APHAB scores also suggested the improvement of the QOL after BAHA usage, except for the scores that concerned with unpleasantness of noisy sound. BAHA is one of the useful options for the treatment of congenital auricular atresia.

Auditory brainstem implant (ABI) is a central prosthesis that directly stimulates the cochlear nucleus in the brainstem for those who have interrupted auditory nerves and cannot benefit from the cochlear implantation. Speech perception in a recipient of the Nuclues 8 channel ABI, the first in Japan, is reported. A 25-year-old man with bilateral acoustic nerve tumors postlingually deafened due to tumor resection received auditory sensations with 5 channels. The correct answer using a coding strategy, SPEAK, was 35% for 5 vowels and 36% for 5 monosyllables. The use of ABI also improved his lip-reading ability on monosyllables and open-set words. This indicated that he benefited from ABI, although it was limited. Even after 1 year and 3 months of follow-up, he had no serious side effects such an infection or implant rejection.

Sound lateralization is considered useful in diagnosing retrocochlear lesions. Interaural time difference (ITD) discrimination has been considered more important than interaural intensity difference (IID) discrimination in diagnosing retrocochlear lesions. The purpose of this study was to determine whether testing sound lateralization by IID and ITD discrimination is useful in patients with acoustic neurinomas (AN). Twenty patients (15 to 74 years old) with unilateral AN were studied by testing IID and ITD discrimination using a self-recording device by delivering 500 Hz band noise through head-phones. Auditory brainstem response (ABR) testing and magnetic resonance imaging (MRI) were also performed in all patients. IID discrimination abnormalities were found in 25% of all patients, and ITD discrimination abnormalities in 85%. Five patients (25%) showed both IID and ITD discrimination abnormalities. One of the three patients with both normal IID and ITD discrimination showed waves I and V, and two of them showed waves I, III and V. One of the five patients with both IID and ITD discrimination abnormalities showed no response, two of them showed only wave I, the other two showed waves I, III and V. Two patients with latency prolongation between waves III and V had both IID and ITD discrimination abnormalities, and seven patients with latency prolongation between waves I and III had normal ITD discrimination or slightly abnormal ITD discrimination and normal IID discrimination. Three of the four patients with large tumors (> 3 cm) had both IID and ITD discrimination abnormalities, while two patients with small ear tumors (< 1 cm) had both normal IID discrimination and normal ITD discrimination. Normal ITD discrimination or slightly abnormal ITD discrimination was found in the majority of patients with wave III. Impairment of ITD discrimination was well correlated with wave III abnormalities. Patients with latency prolongation between waves III and V showed a high degree of ITD discrimination abnormality. Impairment of IID discrimination was related to a high degree of cochlear nerve damage or brainstem damage. We emphasize that IID discrimination is important in the neurological diagnosis of AN, in addition to ITD discrimination. Sound lateralization testing was a useful screening test for diagnosing AN, because tumor size influenced lateralization in every patient, and ITD discrimination was closely correlated with the ABR findings.

Recent progress in magnetic resonance imaging (MRI) has made it possible to obtain detailed images of the inner ear by delineating the lymphatic fluid within the labyrinth. We analyzed CT scans and MR images in 70 ears manifesting profound deafness owing to inner ear lesions and compared their detective ability for inner ear lesions. The following results were obtained. 1) CT scan examination showed slight to extensive ossification of the labyrinth in six ears (9%), whereas MRI examination revealed low to absent signal intensity of the inner ear in nine ears (13%). Therefore, it was concluded that MRI is more sensitive in detecting abnormalities of the inner ear than CT scan. 2) MRI provided useful information as to whether the cochlear turn is filled with lymphatic fluid or obstructed. This point was one of the greatest advantages of MRI over CT scan. 3) Abnormal findings in either or both the CT scan and the MRI were detected in suppurative labyrinthitis occurring secondary to chronic otitis media, bacterial meningitis and in inner ear trauma. However, such abnormal findings were not detected in patients with idiopathic progressive sensorineural hearing loss, ototoxicity or sudden deafness. These findings should be taken into consideration in pre-operative assessment of cochlear implant candidates.

Immediate recall of serial 6 digits was examined in order to clarify whether the electrical information heard via a 22-channel cochlear implant can give rise to normal acoustic memory or not. Serial 6 digits were generated randomly using the digits 1 through 6. Following results were obtained in 2 patients with the implant prosthesis. 1) There was a normal primary effect, i.e., good performance of recall at the first or two digits, and also a normal recency effect, i.e., an increased probability of recall at the last one or two digits. 2) There was a normal suffix effect or attenuation of the recency effect when the digits were followed by an another irrelevant speech suffix, the "8". 3) The suffix effect, however, was not observed when the digits were followed by a non-speech noise suffix. Thus, in noise suffix mode, probability of recall was increased at the last one or two digits as similarly with in no suffix mode. The primary effect, the recency effect and the suffix effect are already regarded as the characteristic items of acoustic memory produced in subjects with normal hearing ability. Therefore, it was suggested that a speech perception with a 22-channel cochlear implant prosthesis can produce an normal acoustic memory, and that there is a similarity of neurophysiological functions between natural audition and electrical audition. Moreover, it was demonstrated that the patients with the cochlear implant can distinguish between speech and noise.

Psychophysical responses of the patients to electrical stimulation were examined in order to clarify long-term effects of the cochlear implant in 9 patients who had received a 22-channel cochlear implant. Measured items were the minimal threshold level (T-level), the maximum comfortable level (C-level), and the dynamic range between T- and C-level. Measurements were repeated for each electrode every three months over more than 6 months. Following results were obtained. 1) The changes of the T-level were classified into four types as follows, a type with no change, a type with gradual decrease, a type with decrease in two to three months followed by gradual increasing threshold and a type with gradual increasing just after surgery. Even in a last type, the maximum increase in the T-level did not exceed 200 microA and, in most cases, these changes were stabilized within a few months after implantation. 2) The dynamic range gradually increased. It was obvious in both in the middle and apical electrodes, while such increased threshold was not observed in the basal electrodes. 3) In some cases, a few basal electrodes could not been used since they caused uncomfortable sensation or those dynamic ranges became below a certain extent. As a result, it was suggested that the electrical stimulation had not induced serious degeneration of the ganglion cells and the auditory nerve fibers. The reduction in the number of usable electrodes might be due to the surgical trauma to the intracochlear tissue. Therefore, exposing of the scala tympani should be minimal in order to avoid the damage of the cochlea.

The diagnosis of the ossicular condition, fixation or interruption, is often not achieved by the tympanometry, because the overlap of the distribution of the static compliance (SC) is so great with the normal group in these two groups. Therefore, it has been said that SC, by itself, has little diagnostic value for differentiating the ossicular lesion. The overlap of the distribution of SC, however, was much smaller between the group with ossicular fixation and the one with ossicular discontinuity. So, apart from deviation from the normal range of SC, the limiting value of SC for discriminating the two groups was determined in ears with conductive hearing loss. The subjects were fifty-one ears with ossicular fixation and seventeen ears with ossicular discontinuity, in which ossicular lesions were surgically confirmed. All ears showed intact tympanic membrane. The limiting value of SC was 0.9 cc. The internal check using this discriminant value showed high ratio of discrimination, i.e. 94.1% in the fixation group and 64.7% in the discontinuity one were diagnosed correctly. Therefore the author proposed this value as the new criteria to differentiate type As ("s" mean sclerosis) tympanogram from type Ad ("d" means discontinuity) one. In addition, the comparison of SC with the normal side in twenty-five unilaterally affected ears showed smaller SC in 75% of the fixation group and larger SC in 92.3% of the discontinuity one than the normal side. Thus, it can be said that SC have useful value in separating ossicular fixation from ossicular discontinuity, if one compares ears with both the intact tympanic membrane and conductive hearing loss.

The development of digital radiography (DR) has made it possible to analyze the contour of the laryngeal soft tissue structures in more detail than the conventional screen-film method. We analyzed the contour of the paralyzed vocal cord during phonation using motion subtraction technique. Forty four patients with unilateral recurrent nerve palsy were examined. The images were obtained by means of frontal tomography of the larynx during quiet inspiration and normal (expiratory) phonation. Tomography during inspiratory phonation was also examined in ten patients who can perform it. The thickness of the slices was 5.0 mm. The authors found that the free margin of the paralyzed vocal cord shifted by the aerodynamic power along the direction of the air flow, i.e. it shifted to the cranial direction during normal phonation and to the caudal during inspiratory phonation. The displacement phenomenon of the paralyzed vocal cord was significantly correlated with the degree of vocal cord atrophy (p less than 0.01). The result would indicate that the aerodynamic power during phonation is one of the factors eliciting the higher position of the paralyzed vocal cord during phonation, in addition to its anatomical displacement due to abduction of the paralyzed arytenoid. This notion should be taken into consideration in selecting the surgical approach for the treatment of unilateral recurrent nerve palsy.