Kristin Daemers

Outcome of cochlear implantation at different ages from 0 to 6 years.

Objective To evaluate the outcome of cochlear implantation in young children in relation to the age at implantation. Study Design A retrospective longitudinal and cross-sectional analysis of pediatric cochlear implant patients. Patients All children with congenital deafness who underwent implantation before the age of 6 years (n = 48 for the longitudinal analysis and n = 70 for the cross-sectional analysis) Interventions All children received a multichannel cochlear implant. Main Outcome Measures Categories of Auditory Performance (CAP) score and integration into the mainstream school system. Results For all children, the CAP score increased after implantation. Implantation beyond the age of 4 years hardly ever resulted in normal CAP scores or in integration into the mainstream primary school (20 to 30% of cases). Implantation between the age of 2 and 4 years always resulted in normal CAP scores after 3 years with a 66% probability of integration into the primary school. Implantation before the age of 2 years always resulted in immediate normalization of the CAP scores, with a 90% probability of integration into the mainstream kindergarten, well before entrance into the primary school. Conclusion All children with congenital deafness who underwent implantation before the age of 6 years appeared to benefit from the implant. However, these data add evidence to the importance of early implantation (before the age of 2 years). Intervention before the age of 4 years seemed to be critical to avoid irreversible auditory performance losses, and intervention before the age of 2 years seemed to be critical to achieve optimal results.

Cochlear implantation between 5 and 20 months of age: the onset of babbling and the audiologic outcome.

Objective: The objective of this study was to investigate the onset of prelexical babbling and the audiologic outcome of 10 deaf children who received a cochlear implant (CI) before the age of 20 months. Study Design: A prospective longitudinal observation and analysis. Patients: Ten congenitally deaf infants implanted at an age between 6 and 18 months. Intervention: All children received a Nucleus-24 multichannel cochlear implant. Main Outcome Measures: 1) The onset of babbling defined as a) the first appearance of multiple articulatory movements and b) a canonical babbling ratio of .2 or higher; 2) the babbling spurt defined as a sudden increase of babbled utterances; 3) the audiologic outcome defined by the CAP score (Categories of Auditory Performance) and the results of the A§E (Auditory Speech Sound Evaluation). Results: All children started babbling after a short interval of 1 to 4 months after activation of the device so that the onset of babbling in the youngest subjects occurred at a chronologic age comparable to that of normally hearing infants. The outcomes of the different babbling measures correlated significantly with the age of implantation: the earlier the implantation, the closer the results approached the outcomes of normally hearing infants. The children implanted in their first year of life showed a normal CAP development as early as 3 months after implantation. All CI children were able to discriminate phoneme pairs of the A§E immediately after the fitting of the device. Conclusions: The earlier the implantation took place, the smaller the delay was in comparison with normally hearing children with regard to the onset of prelexical babbling and with regard to auditory performance as measured by CAP.

Audiological findings in large vestibular aqueduct syndrome

An enlarged vestibular aqueduct is a congenital disorder causing early onset and progressive hearing loss in children. This paper presents the audiological findings at first presentation and the audiological evolution in 10 consecutive cases presenting with hearing loss and showing a large vestibular aqueduct on imaging. The reported onset of the hearing loss is within the first few years of life. Most of the cases (80%) showed bilateral involvement. The sex ratio was 1. Patients presented on average at age 5 with a median hearing loss of 62 dB at the speech frequencies. The hearing loss was essentially asymmetrical with an interaural difference, of 33 dB and it was a mixed type of hearing loss in 90% of the cases. The authors claim that the conductive component of this hearing loss is a pure cochlear conductive loss which may be pathognomonic for the disease. The presence of a conductive component in a child is easily misinterpreted as a middle ear ventilation problem or in case of good ventilation as an ossicular problem (type otosclerosis). In addition and in contrast to most literature data, the authors did not find evidence for stabilization of the hearing loss but they found a steady decrease of the hearing at an average rate of 4 dB/year.

Cochlear implants in aplasia and hypoplasia of the cochleovestibular nerve

Objective To report on the outcome of four patients with aplasia or hypoplasia of the cochleovestibular nerve who have received a cochlear implant. Study Design Retrospective case review. Setting Tertiary referral center. Patients Four patients with: 1) type I aplasia; 2) type IIa aplasia; 3) type IIa hypoplasia; and 4) type IIb aplasia received a cochlear implant. All patients had corner audiograms even with hearing aids. Intervention Three patients received a LAURA multichannel implant, and one patient received a Nucleus 24 implant. Main Outcome Measure Auditory performance, educational setting. Results The patients with type I and type IIb aplasia did not have auditive perception with their implant and became non-users. Both are now in a total communication educational setting. The patients with type IIa aplasia and hypoplasia had moderate audiological results with the implant with audiometrical thresholds of approximately 40–60 dB HL (pure tone average), moderate phoneme discrimination, and poor word discrimination. One child is in a total communication educational setting and the other in an oral educational setting, but the preferred mode of communication remains total communication for both. Both appear to benefit from the implant nonetheless. Conclusion Patients with aplasia/hypoplasia of the cochleovestibular nerve should be counseled with caution with respect to cochlear implantation, but particular circumstances may justify the intervention. At present these circumstances seem to be a type IIa aplasia or hypoplasia in which the end organ (cochlea or common cavity) still connects to a neural structure on MRI.

Long-term evaluation of the effect of intracochlear steroid deposition on electrode impedance in cochlear implant patients.

Objective To evaluate the long-term effect of intracochlear steroid deposition on electrode impedance in patients with cochlear implants. Study Design A retrospective study was carried out comparing the impedances of cochlear implant electrodes with and without a single application of steroids in the cochlea. Patients Ninety two implanted children with an average age of 5 years (range, 0.7 to 16 years) were divided in four groups according to the type of electrode and the use of steroids or not. In addition, the impedances of five children who required a reimplantation are reported. Main Outcome Measure The impedances of Nucleus electrodes, either straight or Contour, were measured at regular intervals up to 12 months after surgery. Results Two months after surgery, the impedances in the steroid groups were significantly lower than in the nonsteroid groups (straight electrodes, 3.9 versus 4.7 kOhm, respectively; Contour electrodes, 5.4 versus 6.5 kOhm, respectively). This reduction remained stable over time for the straight electrodes, but for the Contour electrodes, it seemed to disappear after 6 months. The impedances after a second implantation were significantly higher than after a first implantation (median value, 8.8 kOhm after 2 months). Conclusions The application of a single dose of a steroid solution reduces the electrode impedances significantly, and, for the straight electrodes, this effect seems to last. It seems justified to reimplant with caution, because this seems to increase the impedances substantially.

Contralateral suppression of transient evoked otoacoustic emissions: normative data for a clinical test set-up.

Hypothesis Contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) can be used in a clinical set-up using a procedure based on a unique and robust parameter to quantify the magnitude of suppression for a subject. Background TEOAEs can be suppressed by delivering contralateral white noise (WN). This suppression is thought to be mediated via the efferent nerve fibers that innervate the outer hair cells. The ipsilateral TEOAE-eliciting click stimulus level and the contralateral WN level have a strong impact on the recorded level of suppression. Methods TEOAEs were recorded using the nonlinear stimulation mode in two conditions (with and without contralateral WN). An optimal TEOAE-eliciting click stimulus level and contralateral WN level were defined to obtain a unique and robust parameter to quantify the magnitude of suppression. Results Suppression of TEOAEs with contralateral WN can be measured in a clinical set-up using nonlinear stimulation, and the level of suppression is of the same order of magnitude as measures using the linear stimulation recording mode. The level of suppression appears to be “locked” to the interaural difference between ipsilateral TEOAE-eliciting broadband click stimulus level and the contralateral WN level. Conclusions A procedure is proposed to record contralateral suppression in a clinical set-up, and normative data are given for a normal-hearing population (n = 60).

Numerical assessment of TOAE screening results : Currently used criteria and their effect on TOAE prevalence figures

The literature on neonatal hearing screening by means of oto-acoustic emissions (OAEs) presents various prevalence figures, and gives little quantitative information on the procedure used to score the recordings. If the OAE test is to be interpreted by users who do not have the opportunity to develop intuitive interpretation skills through extensive training, a clear numerical decision criterion is needed. The present paper discusses the scoring procedure used by 25 teams, which together screen 22,356 neonates annually. More than 60% of the groups involved in this study use visual interpretation of the recorded OAE response, together with numerical criteria. Amongst the teams, 21 different ways of numerical scoring are used. It is shown that for a given set of OAE recordings, prevalence varies from 61% to 90%, depending on the numerical decision criterion being applied. We conclude that at this moment no consensus exists regarding the numerical criterion to be used when assessing OAE screening results. In view of the strong effect of criteria on the outcome of OAE screening, such consensus is urgently needed, but should be based on sensitivity and specificity figures for each scoring technique.

Normal Hearing and Language Development in a Deaf-Born Child

Background: Congenital deafness leads to major problems in speech, language, education, and social integration. Neonatal hearing screening and cochlear implantation now allow early hearing restoration. This article reports on a prospective longitudinal study of the first infant ever who received two cochlear implants in the prelexical period of her life. Methods: The first deaf-born girl ever who received two implants at the ages of 5 and 15 months, respectively, was followed-up with repeated and detailed quantitative assessments from birth to 4 years of age. This consisted of 1) audiologic evaluation (audiometry, speech audiometry, and Categories of Auditory Performance score), 2) linguistic evaluation (monthly video analyses and tests of vocabulary, language skills, grammar, and intelligibility of the child’s speech), and 3) descriptive assessment of the educational setting. Results: All results lie within the 95% confidence interval of hearing peers. The audiologic performance lies at or above average from age 2 years onward. The child started babbling at the normal age of 8 months. Her linguistic skills increased from low percentiles before age 2 to above average from age 2 for comprehension and from age 3 for production. The grammar and intelligibility of the child’s speech increased from low percentiles to average at age 4. The girl entered preschool at the normal age of 2.5 years, and this with only very limited special assistance. Conclusion: This case illustrates the fact that congenital deafness no longer has to lead to abnormal hearing and abnormal speech development. It opens the debate of the ethics of not implanting a deaf child in the first few months of life.

A two-stage bipodal screening model for universal neonatal hearing screening

Objective A model is proposed for universal neonatal hearing screening. Methods The screening model is two-staged because it consists of a first test and, in case of failure (1.4% of the subjects), of a retest 3 weeks later. It is bipodal because it involves both the hospital audiologic department and a central Well Baby Organization. The idea is to have a maximal number of newborns tested at the maternity by trained audiologists and to have the Well Baby Organization trace and chase the missing subjects. The model has been evaluated during 1 calendar year (1999) in a maternity with 2,012 newborns. Result The result is a coverage of 99.3%. Most newborns (97.3%) were tested at the maternity ward with a total time investment of less than 15 minutes per child. The actual test time is 2 minutes, 12 seconds (median value). The Well Baby Organization keeps track of all the results and has to test no more than 2% of the newborns. Sensitivity and specificity were not the primary outcomes of this evaluation, but they were similar to those of a previous study evaluating the screen procedure on a larger scale, giving a sensitivity of approximately 100% and a false alarm rate of 1/1,000. Conclusion These figures demonstrate that universal neonatal hearing screening is feasible within the existing health care structure, with unprecedented coverage, sensitivity, and specificity.

Development of a Software Tool Using Deterministic Logic for the Optimization of Cochlear Implant Processor Programming

Objective: An intelligent agent, Fitting to Outcomes eXpert, was developed to optimize and automate Cochlear implant (CI) programming. The current article describes the rationale, development, and features of this tool. Background: Cochlear implant fitting is a time-consuming procedure to define the value of a subset of the available electric parameters based primarily on behavioral responses. It is comfort-driven with high intraindividual and interindividual variability both with respect to the patient and to the clinician. Its validity in terms of process control can be questioned. Good clinical practice would require an outcome-driven approach. An intelligent agent may help solve the complexity of addressing more electric parameters based on a range of outcome measures. Methods: A software application was developed that consists of deterministic rules that analyze the map settings in the processor together with psychoacoustic test results (audiogram, A§E phoneme discrimination, A§E loudness scaling, speech audiogram) obtained with that map. The rules were based on the daily clinical practice and the expertise of the CI programmers. The data transfer to and from this agent is either manual or through seamless digital communication with the CI fitting database and the psychoacoustic test suite. It recommends and executes modifications to the map settings to improve the outcome. Results: Fitting to Outcomes eXpert is an operational intelligent agent, the principles of which are described. Its development and modes of operation are outlined, and a case example is given. Fitting to Outcomes eXpert is in use for more than a year now and seems to be capable to improve the measured outcome. Conclusion: It is argued that this novel tool allows a systematic approach focusing on outcome, reducing the fitting time, and improving the quality of fitting. It introduces principles of artificial intelligence in the process of CI fitting.