Andy Beynon

Speech-evoked cortical potentials and speech recognition in cochlear implant users.

Processing in the auditory cortex may play a role in the unexplained variability in cochlear implant benefit. P300 and N1/P2 were elicited in post-lingually deaf cochlear implant users wearing a Nucleus multichannel cochlear implant. Four sound contrasts were presented (500-1000 Hz, /ba/-/da/, /ba/-/pa/ and /i/-/a/). N1 and P2 were present in all subjects for all conditions. Prolonged N1, P2 and P300 latencies were found in the cochlear implant group compared to a control group of subjects with normal hearing. Cochlear implant users show smaller amplitudes of N1 for all the speech signals as well as smaller amplitudes of P2 for the consonants compared to the controls. P300 results of the cochlear implant users were compared to behavioural results of speech recognition testing. A relation was found between P300 amplitude and magnitude for the 500-1000 Hz and /i/-/a/ contrasts and behavioural speech recognition in cochlear implant users. The results suggest that P300 measurements are useful and have additional value to speech recognition evaluations in cochlear implant users.

Binaural application of the bone-anchored hearing aid.

Most, but not all, hearing-impaired patients with air conduction hearing aids prefer binaural amplification instead of monaural amplification. The binaural application of the bone conduction hearing aid is more disputable, because the attenuation (in decibels) of sound waves across the skull is so small (10 dB) that even one bone conduction hearing aid will stimulate both cochleas approximately to the same extent. Binaural fitting of the bone-anchored hearing aid was studied in three experienced bone-anchored hearing aid users. The experiments showed that sound localization, and speech recognition in quiet and also under certain noisy conditions improved significantly with binaural listening compared to the monaural listening condition. On the average, the percentage of correct identifications (within 45°) in the sound localization experiment improved by 53% with binaural listening; the speech reception threshold in quiet improved by 4.4 dB. The binaural advantage in the speech-in-noise test was comparable to that of a control group of subjects with normal hearing listening monaurally versus binaurally. The improvements in the scores were ascribed to diotic summation (improved speech recognition in quiet) and the ability to separate sounds in the binaural listening condition (improved sound localization and improved speech recognition in noise whenever the speech and noise signals came from different directions). All three patients preferred the binaural bone-anchored hearing aids and used them all day.

Evaluation of cochlear implant benefit with auditory cortical evoked potentials.

Endogenous P300 and exogenous slow vertex potentials were obtained with tone and speech stimuli in a group of five children using a cochlear implant (CI) with poor speech recognition (group A) and compared with those from another group of five children using a CI with good speech recognition (group B). The responses were also compared to those of children with normal hearing (n = 14) and a group of adult CI users (n = 9). N1 and P2 latencies of CI group A and group B were prolonged compared to those of normally-hearing children. In group A, P300 was present when contrasts with tone stimuli were used. When speech stimuli were used, P300 potentials were absent or delayed. P300 potentials obtained in group B were no different from those obtained in normally-hearing children. It is suggested that the poor results evoked with speech stimuli in contrast to those evoked with pure-tone stimuli in group A are due to the immaturity of (sub) cortical generators associated with acoustical and phonetic processing. In contrast to the children in group B, all children in group A suffered from congenital deafness. Sumario Se compararon los potenciales endógenos P300 y los potenciales exógenos lentos del vértex con estímulos tonales y de lenguaje en dos grupos diferentes. El grupo A estaba conformado por cinco niños con implante coclear, con pobre discriminación del lenguaje. El grupo B igual-mente conformado por cinco niños, pero con buena discriminación del lenguaje. Las respuestas también fueron comparadas con las de niños con audición normal (n = 14) y con un grupo de adultos con implante coclear (n = 9). Las latencias de N1 y P2 estaban prolongadas en los grupos A y B en comparación con las de los niños normoyentes. En el grupo A, la P300 se presentó cuando se utilize contraste con el estimulo tonal. Cuando se utilizó estímulo lingüístico la P300 estuvo ausente o retrasada. Los potenciales obtenidos en el grupo B no mostraron diferencia con aquellos obtenidos en niños normoyentes. Se piensa que la inmadurez de los generadores (sub) corticales asociados con el procesamiento fonético y acústico, son la causa de los pobres resultados obtenidos con el estímulo lingüístico que con-trastan con los resultados obtenidos al estimular con tonos puros. A diferencia de los niños del grupo B, la sordera de los niños en el grupo A era congenita.

A retrospective Multicenter Study comparing Speech Perception outcomes for Bilateral Implantation and Bimodal rehabilitation

Objectives: To compare speech perception outcomes between bilateral implantation (cochlear implants [CIs]) and bimodal rehabilitation (one CI on one side plus one hearing aid [HA] on the other side) and to explore the clinical factors that may cause asymmetric performances in speech intelligibility between the two ears in case of bilateral implantation. Design: Retrospective data from 2247 patients implanted since 2003 in 15 international centers were collected. Intelligibility scores, measured in quiet and in noise, were converted into percentile ranks to remove differences between centers. The influence of the listening mode among three independent groups, one CI alone (n = 1572), bimodal listening (CI/HA, n = 589), and bilateral CIs (CI/CI, n = 86), was compared in an analysis taking into account the influence of other factors such as duration of profound hearing loss, age, etiology, and duration of CI experience. No within-subject comparison (i.e., monitoring outcome modifications in CI/HA subjects becoming CI/CI) was possible from this dataset. Further analyses were conducted on the CI/CI subgroup to investigate a number of factors, such as implantation side, duration of hearing loss, amount of residual hearing, and use of HAs that may explain asymmetric performances of this subgroup. Results: Intelligibility ranked scores in quiet and in noise were significantly greater with both CI/CI and CI/HA than with a CI-alone group, and improvement with CI/CI (+11% and +16% in quiet and in noise, respectively) was significantly better than with CI/HA (+6% and +9% in quiet and in noise, respectively). From the CI/HA group, only subjects with ranked preoperative aided speech scores >60% performed as well as CI/CI participants. Furthermore, CI/CI subjects displayed significantly lower preoperative aided speech scores on average compared with that displayed by CI/HA subjects. Routine clinical data available from the present database did not explain the asymmetrical results of bilateral implantation. Conclusions: This retrospective study, based on basic speech audiometry (no lateralization cues), indicates that, on average, a second CI is likely to provide slightly better postoperative speech outcome than an additional HA for people with very low preoperative performance. These results may be taken into consideration to refine surgical indications for CIs.

A Comparison of Surgical Treatments for Superior Semicircular Canal Dehiscence: A Systematic Review

OBJECTIVE We investigate the postoperative subjective and objective outcomes of different surgical treatments for superior semicircular canal dehiscence (SSCD): vestibular signs, auditory signs, vestibular evoked myogenic potential test, pure tone audiogram, speech audiogram, or video-nystagmography. DATA SOURCES An electronic search performed in the PubMed, Cochrane Library, and EMBASE databases on 15th of September 2015. A systematic search was conducted. Articles were included if written in English, Dutch, German, or French language. STUDY SELECTION Original studies reporting on the pre and postoperative subjective and/or objective outcomes of surgical treatments for superior semicircular canal dehiscence were included. DATA EXTRACTION The methodological quality of the studies was independently assessed by two reviewers using a constructed critical appraisal, to assess the directness of evidence and the risk of bias. The results of the pre and postoperative subjective and/or objective outcomes were extracted. DATA SYNTHESIS Comparative study was conducted. CONCLUSION Surgical treatment for SSCD is particularly effective for vestibular symptoms and there is no evidence for improvement of hearing loss after surgical treatment. Since plugging using transmastoid approach had a lower complication rate, lower revision rate, and a shorter hospital stay, this treatment is recommended in high disabled SSCD patients.

Electrically evoked auditory brainstem responses in children with sequential bilateral cochlear implants.

Objective: To examine the effect of sequential bilateral cochlear implantation on auditory brainstem maturation and the effect of age in receiving the second implant (CI2). Study Design: Prospective cohort study. Setting: Tertiary academic referral center. Patients: Thirty prelingually deaf children, who received their first implant (CI1) at a mean age of 1.8 year and their CI2 at a mean age of 5.3 years. Intervention: Sequential bilateral cochlear implantation. Main Outcome Measure: Electrically evoked auditory brainstem responses on the 2 implant sides were measured intraoperatively and postoperatively after 6, 12, and 24 months of bilateral implant use. Results: Electrically evoked auditory brainstem response latencies on the 2 implants were compared within subjects over time. Wave III did not show any significant differences between the 2 sides, whereas Wave V was initially prolonged on the CI2 side compared with the CI1 side. Although still apparent, this interaural latency difference of Wave V was no longer significant after 12 and 24 months. Interwave interval III to V latencies remained significantly prolonged on the CI2 side. Age in receiving the CI2 did not account for the individual differences in latencies for all waveforms. Conclusion: The present data suggest that auditory brainstem maturation will occur after a relatively long period of unilateral deafness irrespective of the age in receiving the CI2. Because some abnormalities were still seen at the upper part of the brainstem, our results indicate that the CI2 side has not caught up with the CI1 side. Nevertheless, within our follow-up time, interaural (interwave) latencies decrease significantly, and longer-term data might reveal that the CI2 eventually will catch up with the CI1 side.

Clinical evaluation of cochlear implant sound coding taking into account conjectural masking functions, MP3000™

Abstract Efficacy of the SPEAK and ACE coding strategies was compared with that of a new strategy, MP3000™, by 37 European implant centers including 221 subjects. The SPEAK and ACE strategies are based on selection of 8–10 spectral components with the highest levels, while MP3000 is based on the selection of only 4–6 components, with the highest levels relative to an estimate of the spread of masking. The pulse rate per component was fixed. No significant difference was found for the speech scores and for coding preference between the SPEAK/ACE and MP3000 strategies. Battery life was 24% longer for the MP3000 strategy. With MP3000 the best results were found for a selection of six components. In addition, the best results were found for a masking function with a low-frequency slope of 50 dB/Bark and a high-frequency slope of 37 dB/Bark (50/37) as compared to the other combinations examined of 40/30 and 20/15 dB/Bark. The best results found for the steepest slopes do not seem to agree with current estimates of the spread of masking in electrical stimulation. Future research might reveal if performance with respect to SPEAK/ACE can be enhanced by increasing the number of channels in MP3000 beyond 4–6 and it should shed more light on the optimum steepness of the slopes of the masking functions applied in MP3000.

Nonsyndromic Hearing Loss Caused by USH1G Mutations: Widening the USH1G Disease Spectrum

Objective: Currently, six genes are known to be associated with Usher syndrome type I, and mutations in most of these genes can also cause nonsyndromic hearing loss. The one exception is USH1G, which is currently only known to be involved in Usher syndrome type I and atypical Usher syndrome. Design: A Dutch family with autosomal recessively inherited hearing loss was examined. Audiometric, ophthalmic, and vestibular evaluations were performed besides the genetic analysis. Results: The hearing loss had an early onset with a downsloping audiogram configuration. Slight progression of the hearing loss was seen in both affected individuals. Compound heterozygous mutations in USH1G were found to segregate with the hearing loss in this family, a missense (c.310A>G, p.Met104Val) and a frameshift mutation (c.780insGCAC, p.Tyr261Alafs*96). Extensive ophthalmic and vestibular examinations demonstrated no abnormalities that are usually associated with Usher syndrome type I. Conclusions: This is the first family presented with nonsyndromic hearing loss caused by mutations in USH1G. Our findings expand the phenotypic spectrum of mutations in USH1G.

Auditory cortical maturation in children with sequential bilateral cochlear implants.

Objective To assess the effect of sequential bilateral cochlear implantation on auditory, cortical maturation after various periods of unilateral cochlear implant use. Study Design Prospective cohort study. Setting Tertiary academic referral center. Patients Thirty prelingually deaf children, who received their first implant at a mean age of 1.8 years and their second implant at a mean age of 5.3 years. Intervention Sequential bilateral cochlear implantation. Main Outcomes Measure The electrically evoked auditory cortical response (EACR) was evoked by the 2 implants separately after 12 and 24 months of bilateral cochlear implant use. P1 and N2 latencies and RMS amplitudes were compared between both implant sides and were compared with those of a group of 27 age-matched children with normal hearing. Results EACR latencies diminished over time for both implant sides. RMS amplitudes and P1 latencies elicited by the second implant were still significantly different from that of the first implant after 24 month. After 24 months, the difference in N2 latencies between both implant sides was no longer significant, although still apparent. Interimplant delay had an adverse effect on RMS amplitudes and waveform morphology. EACR latencies were age appropriate, although RMS amplitudes evoked by the second implant were smaller than those of the children with normal hearing. Conclusion Auditory cortical maturation is possible after extended unilateral cochlear implant use, although responses evoked by the second implant still lack behind that of the experienced first implant. It is not clear if the auditory cortical response will become similar on both implant sides over time, especially for the children with longer interimplant delays.

Percutaneous titanium implantation in the skull for the bone-anchored hearing aid.

In the 1980s, a new type of bone conduction hearing aid was developed in Göteborg, Sweden. With this new bone-anchored hearing aid (BAHA) system, sound waves are transmitted directly to the skull by means of a titanium screw implanted into the skull. The advantages and disadvantages of the conventional hearing aid and the BAHA are described here. In the 25 patients presented, all the percutaneous implants remained firmly anchored in the skull. One screw was lost through trauma. The scores on the speech recognition-in-noise and the speech recognition-in-quiet tests were significantly higher in 64% and 32% of the patients with a BAHA, respectively.