Yusuke Akamatsu

Vestibular evoked myogenic potentials evoked by multichannel cochlear implant – influence of C levels

Conclusions. This study showed that vestibular evoked myogenic potentials (VEMPs) evoked by cochlear implant (CI), could be related to the comfortable level (C level), particularly in the channels that are closer to the apical turn of the cochlea. Objective. The purpose of this study was to investigate the correlation between VEMPs and C level of each channel. Subjects and methods. We investigated 24 children who underwent cochlear implantation. VEMPs were recorded from the operated ears with the CI switched ‘off’ or ‘on’. To investigate the correlation between VEMPs and C level, we selected 13 patients with Nucleus 24 (SPrint), and divided them into group A (normal VEMPs) and B (absence of VEMPs). In these children, all the 22 electrodes were active, and were mapped in the same frequency range for each channel. Results. Twenty children (83%) showed no VEMPs with the CI ‘off’. Among them, 10 elicited VEMPs with the CI ‘on’, but the other 10 did not. In all channels, the mean C levels of CI were higher in group A than in group B. The p values in channels 1–12 were >0.10, in channels 13–16 were 0.06–0.09, and in channels 17–22 were 0.05–0.06, which were lower but not statistically significant.

Vestibular evoked myogenic potentials of children with inner ear malformations before and after cochlear implantation.

Conclusions: Our results show that among the patients with inner ear malformations, there were two patients with sensory cells of sacculus and inferior vestibular neurons and at least five patients with inferior vestibular neurons only, but no patients without sensory cells and vestibular neurons, as determined on the basis of vestibular evoked myogenic potentials (VEMPs). Objective: The aim of this study was to investigate whether sensory cells of sacculus or inferior vestibular neurons or both are present in cochlear implant patients with inner ear malformations, particularly common cavity (CC) deformity, using VEMPs. Patients and methods: Seven children with inner ear malformation who underwent cochlear implantation (CI) participated in this study. The patients had CC deformity (n=2), incomplete partition type I (n=2), incomplete partition type II (n=1), or a narrow internal auditory canal (IAC) (n=2). It was possible to record VEMPs before and after CI in three patients and not before but after CI in four patients. After surgery, VEMPs were recorded with the cochlear implant device switched both off and on. Results: Before the CI, two patients showed VEMPs and one patient showed no VEMPs, whereas in four patients no VEMPs could be recorded. All the patients showed VEMPs with the cochlear implant on.

Development of auditory skills after cochlear implantation in children with inner ear malformations

Abstract Conclusions: CI improves hearing thresholds and auditory skills in children with most types of inner ear malformations. However, the development of sound detection skills is not as good as it is in children without inner ear malformations. Objectives: To investigate the influence of inner ear malformations on development of auditory skills after cochlear implantation (CI). Methods: Records of 20 children with inner ear malformations who underwent cochlear implantation before 4 years of age and followed up for more than 2 years were retrospectively reviewed. Hearing thresholds, the Meaningful Auditory Integration Scale (MAIS), and Meaningful Use of Speech Scale (MUSS) scores before and after CI were analyzed and compared with 20 age-matched deaf children who underwent CI. Results: The children with inner ear malformations showed significant improvements in hearing thresholds and the MAIS and MUSS scores 1 year after CI (p < 0.01). However, their development of the MAIS scores was significantly delayed compared to children without inner ear malformations (p < 0.05), while there was no significant difference in development of the MUSS scores between them. Significant improvements in hearing thresholds and the MAIS and MUSS scores were observed in cochlear hypoplasia and incomplete partition (p < 0.05).

Spontaneous otoacoustic emissions in two infants

Conclusion: We regard spontaneous otoacoustic emission (SOAE) as a unique phenomenon due to spontaneous outer hair cell hyperactivity during the infantile period in these two infants. Objectives: We report the cases of SOAEs in two infants, which were audible to their parents. We were able to hear continuous sounds from these two infants’ ears. We studied their hearing and the emitted sounds objectively. Patients and methods: Patient 1 was a 5-month-old girl and patient 2 was an 11-month-old girl. Their parents heard continuous sounds emanating from their infants’ ears. Audiological examinations and frequency analysis were conducted. Results: The distortion-product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs) of the two patients were normal. Analysis of the continuous sounds demonstrated frequencies of 4.2 and 6.5 kHz for patient 1 and 6.7 kHz for patient 2. These audible sounds were diagnosed as SOAEs. The SOAEs in these infants did not disappear with their development in the last 2 years.

Environmental sound perception in adult patients with cochlear implants: a comparison with central auditory disorders.

Abstract The aim of this study is to investigate the perception mechanism of environmental sounds in postlingual patients with cochlear implants compared with that in patients with central auditory disorders. Seventeen postlingual patients with cochlear implants were studied; six patients with auditory nerve disease (auditory neuropathy) and ten patients with cortical deafness were selected for the comparison. A taperecorded environmental sound perception test of 24 environmental sounds was carried out. This test is divided into two categories: the category of voice includes human voice, animal and bird sounds, and the category of non-voice includes musical instrument sound, natural sound and artificial sound. The percentage of correct perception of environmental sounds in postlingually deaf patients with cochlear implants was markedly higher than that in patients with cortical deafness, but was similar to that in patients with auditory nerve disease (auditory neuropathy).

Environmental Sound Perception in Patients with Cochlear Implants Compared with That in Patients with Auditory Nerve Diseases (Auditory Neuropathy) and Cortical Deafness

The mechanism for perception of environmental sounds is considered to be different from the cognitive mechanism of language. The environmental sound perception of cochlear implantees appears to be good but not perfect. However, its underlying mechanism is not yet known. The aim of this study was to investigate perception of environmental sounds in postlingually deaf patients with cochlear implants compared with that in patients with central auditory disorders. Seventeen postlingual patients with cochlear implants, 6 patients with auditory nerve disease (auditory neuropathy), and 10 patients with cortical deafness were selected for the comparison. A tape-recorded environmental sound perception test of 24 environmental sounds, which was developed by the authors in 1987, was used. This test is divided into two categories: the category of vocalization includes human voice as well as animal and bird sounds, and the category of non-voice sounds includes sounds of nature and musical instruments, as well as sounds from man-made sources. The test procedure consists of two steps. The fi rst step (open set) is only to listen and to identify each sound either orally or in writing. The second step (closed set) is to listen and chooses a picture card matching test form among four different pictures. The percentages of correctly identifi ed environmental sounds in postlingually deaf patients with cochlear implants was markedly higher than that in patients with cortical deafness, but was similar to that in patients with auditory nerve disease (auditory neuropathy), in both the closed and open sets. Our study revealed that the perception of environmental sounds in postlingual patients with cochlear implants was not good in the open set but markedly better in the closed set. This result is similar to those for auditory nerve disease patients but completely different from those for cortical deafness patients. The ability of patients with cochlear implants to perceive environmental sounds is similar to that of patients with auditory nerve disease, perhaps because information carried by the cochlear nerve is similarly degraded.

Outcomes of cochlear implantations for mumps deafness: A report of four pediatric cases

Mumps virus occasionally causes bilateral hearing loss. We report 4 cases of bilateral mumps deafness in whom cochlear implantations (CI) were performed. The age at the onset of hearing loss was 1-9 years. CI surgery was performed within 6 months from the onset of hearing loss in 3 cases and after 9 years in the other case, showing good speech perception in the early intervention cases and a poor outcome after later implantation. Early CI surgery is highly recommended in sudden onset deafness by mumps in childhood.

Cochlear Implantation Outcome in Patients with Common Cavity Deformity

Objectives: (1) Analyze our own cases and those in published reports involving cochlear implantation (CI). (2) Determine the factors affecting outcome in patients with common cavity (CC) deformity. Methods: We reviewed the English and Japanese literature published from January 1995 to December 2013 using the keywords “CC,” “CI,” and “cochlear malformation.” We included cochlear implanted CC patients whose records on occurrence of cerebral spinal fluid (CSF) gusher, facial nerve stimulation (FNS), number of inserted and actively used electrodes, or hearing levels before or after CI were available. Results: A total of 72 cochlear implanted CC patients were identified from 11 reports, including 5 patients from our institution. Individual hearing results as monosyllable and word scores were reported in 9 and 15 patients, respectively. Monosyllable hearing levels were greater in patients inserted with ≥20 electrodes and in those younger at time of CI. CSF gusher occurred in 18 (32%) of 57 patients, and FNS occurred in 12 (44%) of 27 patients. Conclusions: Individual data are important in assessing the outcome after CI in patients with CC because the outcomes vary significantly. Although there have been several reports, only a few have reported efficient data to discuss the propriety of each operation. Younger age at CI and greater number of inserted electrodes were associated with better outcome following CI in patients with CC. However, additional data are needed to confirm our findings.

Audio-Visual Vowel Perception of Cochlear Implant Users

Objectives: We created a vowel perception test to analyze the contribution of visual and auditory inputs during vowel processing in cochlear implant (CI) users. Methods: We enrolled 30 adults and 40 children who received cochlear implants (CI). Ten adults and 11 children with normal hearing (NH) also participated as controls. The auditory stimuli were 5 Japanese vowels and the visual stimuli were apparent motions that were succeeded by pictures of faces. The following three test conditions were used: 1) AV, the matched pairs of visual and auditory stimuli, 2) AV-mismatch, the inconsistent pairs of stimuli, and 3) A-only. During the session, the subjects were instructed to judge which vowel was said and to press the correct button. Correct rate and reaction time were measured. Results: Correct rate in AV-mismatch and A-only condition was significantly higher in NH compared to CI. Correct rate of AV-mismatch condition was significantly lower than that of AV and A-only conditions in CI. Moreover, CI took longer reaction time in AV-mismatch condition compared to other conditions. We found that the degree of visual dependence of adult CI users was correlated with speech discrimination score, but not age, duration of deafness, or duration of CI use. Among pediatric CI users, mode of communication during preschool period affected the results. Conclusions: The aural group showed results similar to those of adult CI users, which imply that their processing of visual and auditory inputs is close to those who learned speech and language through the auditory modality.