Nicolas Verhaert

Impact of early hearing screening and treatment on language development and education level: Evaluation of 6 years of universal newborn hearing screening (ALGO®) in Flanders, Belgium

OBJECTIVES Early intervention in hearing-impaired children may improve language outcomes and subsequent school and occupational performance. The objective of this study was to retrospectively analyze over 6 years the educational outcome and language development of a first cohort of children, detected by the Flemish universal newborn hearing screening (UNHS) program based on automated auditory brainstem response (AABR), with the oldest children being in primary school. METHODS We studied 229 hearing-impaired children from 1998 till 2003. The following variables were considered: the age during the school year 2005-2006, the degree of hearing loss, additional impairments including presence of intellectual disability, school placement and early intervention. RESULTS Analysis showed that 85.4% of the children with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Further detailed description was provided for the outcomes of children with uni- and bilateral cochlear implants. Overall results stress that 46% of all children with a cochlear implant obtain mainstream education. Of all cochlear implant (CI) children above 5.5 years, without additional handicaps, 78.9% of children attend primary mainstream school. Data on language development show that up to 45% of the children with unilateral cochlear implant and no additional disabilities had normal to slight delay on language development. These data are fulfilling the goals stated by the JCIH and the American Academy of Pediatrics (AAP) in 2000. The role and impact of additional handicaps is discussed. The importance of early hearing loss identification and hearing therapy for appropriate language development is highlighted. Finally our preliminary results on children with bilateral cochlear implants without additional handicaps present an improved language development in comparison to unilateral CI-children. CONCLUSION A vast majority of the children detected by the UNHS program, with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Additional disabilities have a major influence.

A comparative study on speech in noise understanding with a direct acoustic cochlear implant in subjects with severe to profound mixed hearing loss.

The aim of this study was to investigate the efficacy of a direct acoustic cochlear implant (DACI) for speech understanding in noise in patients suffering from severe to profound mixed hearing loss (MHL) due to various etiologies compared to the preoperative best-aided condition. The study was performed at five tertiary referral centers in Europe (Belgium, Germany, Poland and Spain). Nineteen adult subjects with severe to profound MHL due to (advanced) otosclerosis, ear canal fibrosis, chronic otitis media, tympanosclerosis or previous cholesteatoma were implanted with a DACI (Codacs™ Investigational Device) combined with a conventional stapes prosthesis. Unaided and aided speech reception scores in quiet and in noise, preoperative and postoperative air and bone conduction thresholds and aided and unaided sound field thresholds were measured prospectively during the study. Subjective benefit analysis was determined through the Abbreviated Profile of Hearing Aid Benefit questionnaire. Quality of life was measured by the Health Utilities Index. All subjects were fitted preoperatively with hearing aids and/or a bone conduction implant on a headband before DACI implantation. This allows direct comparison between different hearing rehabilitation solutions. The mean speech reception threshold in noise improved significantly by 7.9 dB signal-to-noise ratio (SNR) after activation of the DACI compared to the preoperative best-aided condition. For all 19 subjects, a mean postoperative aided speech reception threshold of 2.6 dB SNR (standard deviation: 8.3 dB) was measured. On average, no significant shift in the bone conduction thresholds was noted 4-5 months after implantation. A mean sound field threshold improvement of 46 and 16 dB was measured compared to the preoperative unaided and best-aided condition, respectively. Speech perception tests in quiet showed a mean improvement of the word recognition scores by 65 and 48% at 65 dB SPL compared to the preoperative unaided and best-aided condition, respectively. In summary, DACI provides an effective improvement of the speech perception in noise compared to the best-aided condition in subjects suffering from severe to profound MHL.

Acoustic hearing implants for mixed hearing loss: a systematic review.

Objective A systematic review of literature to determine the clinical outcome and safety of the range of acoustic hearing implants (AHIs) in adults with mixed hearing loss (MHL). Data Sources Databases MEDLINE, Embase, and Cochrane were searched with no language restrictions between 1950, or the start date of each database, up to March 1, 2013. Study Selection Initial search found 1,794 studies, of which, 19 met the inclusion criteria of AHI for adults with MHL where safety, coupling strategies to the inner ear, hearing outcome, and patient-reported outcome measures (PROMs) were analyzed, preferably compared with a conventional hearing aid or a bone-conduction implant. Data Extraction A study quality assessment based on different parameters was included: specification of eligibility criteria, prospective study, ethical approval gained, appropriate controls, power calculation, outcome measures, and analysis performed. Data Synthesis Comparisons between studies were made based on structured review as meta-analysis was not feasible because of the heterogeneity of outcome measures and reports. Conclusion The current systematic review shows that AHI and their different coupling strategies in the treatment of MHL were beneficial in terms of speech in quiet, PROM, and safety regarding residual hearing. Overall, the level of evidence and the quality of the included studies were judged to be moderate to low. More comprehensive data on coupling to the inner ear and the comparison with conventional hearing aids or alternatives for speech in noise is mandatory. Long-term follow-up data are also needed. Level of Evidence 3a.

Prevalence and Nature of Hearing Loss in 22q11.2 Deletion Syndrome.

PURPOSE The purpose of this study was to clarify the prevalence, type, severity, and age-dependency of hearing loss in 22q11.2 deletion syndrome. METHOD Extensive audiological measurements were conducted in 40 persons with proven 22q11.2 deletion (aged 6-36 years). Besides air and bone conduction thresholds in the frequency range between 0.125 and 8.000 kHz, high-frequency thresholds up to 16.000 kHz were determined and tympanometry, acoustic reflex (AR) measurement, and distortion product otoacoustic emission (DPOAE) testing were performed. RESULTS Hearing loss was identified in 59% of the tested ears and was mainly conductive in nature. In addition, a high-frequency sensorineural hearing loss with down-sloping curve was found in the majority of patients. Aberrant tympanometric results were recorded in 39% of the ears. In 85% of ears with a Type A or C tympanometric peak, ARs were absent. A DPOAE response in at least 6 frequencies was present in only 23% of the ears with a hearing threshold ≤30 dB HL. In patients above 14 years of age, there was a significantly lower percentage of measurable DPOAEs. CONCLUSION Hearing loss in 22q11.2 deletion syndrome is highly prevalent and both conductive and high-frequency sensorineural in nature. The age-dependent absence of DPOAEs in 22q11.2 deletion syndrome suggests cochlear damage underlying the high-frequency hearing loss.

Aetiology of congenital hearing loss: a cohort review of 569 subjects.

OBJECTIVE Newborn hearing screening was implemented in Flanders about fifteen years ago. The aim of this study was to determine the aetiology of hearing loss detected by the Flemish screening programme. METHODS From 1997 to 2011, 569 neonates were referred to our tertiary referral centre after failed neonatal screening with Auditory Brainstem Responses. In case hearing loss (HL) was confirmed, further diagnostic testing was launched. A retrospective chart review was performed analysing the degree of HL, risk factor and aetiology. RESULTS Metabolic disorders (0.5%), infectious diseases (35.8%), congenital malformations (6.1%) and genetic abnormalities (19.8%), whether or not syndromic, were retained. In 35% of the subjects no obvious aetiology could be determined in the current study. CONCLUSION In contrast to the literature findings, this series shows a genetic syndromic cause in 80% of the genetic bilateral HL cases. On the other hand connexin positive diagnoses were mostly underrepresented in this study, showing the need for better screening.

Assessment of Ipsilateral Efferent Effects in Human via ECochG

Development of electrophysiological means to assess the medial olivocochlear (MOC) system in humans is important to further our understanding of the function of that system and for the refinement and validation of psychoacoustical and otoacoustic emission methods which are thought to probe the MOC. Based on measurements in anesthetized animals it has been hypothesized that the MOC-reflex (MOCR) can enhance the response to signals in noise, and several lines of evidence support such a role in humans. A difficulty in these studies is the isolation of efferent effects. Efferent activation can be triggered by acoustic stimulation of the contralateral or ipsilateral ear, but ipsilateral stimulation is thought to be more effective. However, ipsilateral stimulation complicates interpretation of effects since these sounds can affect the perception of other ipsilateral sounds by mechanisms not involving olivocochlear efferents. We assessed the ipsilaterally evoked MOCR in human using a transtympanic procedure to record mass-potentials from the cochlear promontory or the niche of the round window. Averaged compound action potential (CAP) responses to masked probe tones of 4 kHz with and without a precursor (designed to activate the MOCR but not the stapedius reflex) were extracted with a polarity alternating paradigm. The masker was either a simultaneous narrow band noise masker or a short (20-ms) tonal ON- or OFF-frequency forward masker. The subjects were screened for normal hearing (audiogram, tympanogram, threshold stapedius reflex) and psychoacoustically tested for the presence of a precursor effect. We observed a clear reduction of CAP amplitude by the precursor, for different masking conditions. Even without an MOCR, this is expected because the precursor will affect the response to subsequent stimuli via neural adaptation. To determine whether the precursor also activated the efferent system, we measured the CAP over a range of masker levels, with or without precursor, and for different types of masker. The results show CAP reduction consistent with the type of gain reduction caused by the MOCR. These results generally support psychoacoustical paradigms designed to probe the efferent system as indeed activating the MOCR system, but not all observations are consistent with this mechanism.

Malformations of the middle and inner ear on CT imaging in 22q11 deletion syndrome

The 22q11 deletion syndrome (22q11DS), the most frequent microdeletion syndrome in humans, presents with a large variety of abnormalities. A common abnormality is hearing impairment. The exact pathophysiological explanation of the observed hearing loss remains largely unknown. The aim of this study was to analyze the middle and inner ear malformations as seen on computer tomographic imaging in patients with 22q11DS. We retrospectively reviewed the charts of 11 22q11DS patients who had undergone a CT of the temporal bone in the past. Of the 22 examined ears, two showed an abnormal malleus and incus, 10 presented with a dense stapes superstructure, and three ears had an abnormal orientation of the stapes. With regard to the inner ear, 12 ears showed an incomplete partition type II with a normal vestibular aqueduct. In four ears the vestibule and lateral semicircular canal were composed of a single cavity, in 14 ears the vestibule was too wide, and three ears had a broadened lateral semicircular canal. These findings suggest that malformations of the stapes, cochlea, vestibule, and lateral semicircular canal are frequent in 22q11DS. To our knowledge, the current study involves the largest case series describing middle and inner ear malformations in 22q11DS.

Surgical Management and Hearing Outcome of Traumatic Ossicular Injuries

OBJECTIVE The purpose of this study was to investigate etiological, clinical, and pathological characteristics of traumatic injuries of the middle ear ossicular chain and to evaluate hearing outcome after surgery. MATERIAL AND METHODS Thirty consecutive patients (31 ears) with traumatic ossicular injuries operated on between 2004 and 2015 in two tertiary referral otologic centers were retrospectively analyzed. Traumatic events, clinical features, ossicular lesions, treatment procedures, and audiometric results were evaluated. Air conduction (AC), bone conduction (BC), and air-bone gap (ABG) were analyzed preoperatively and postoperatively. Amsterdam Hearing Evaluation Plots (AHEPs) were used to visualize the individual hearing results. RESULTS The mean age at the moment of trauma was 27.9±17.1 years (range, 2-75 years) and the mean age at surgery was 33.2±16.3 years (range, 5-75 years). In 10 cases (32.3%), the injury occurred by a fall on the head and in 9 (29.0%) by a traffic accident. Isolated luxation of the incus was observed in 8 cases (25.8%). Dislocation of the stapes footplate was seen in 4 cases (12.9%). The postoperative ABG closure to within 10 and 20 dB was 30% and 76.7%, respectively. CONCLUSION Ossicular chain injury by direct or indirect trauma can provoke hearing loss, tinnitus, and vertigo. As injuries are heterogeneous, they require a tailored surgical approach. In this study, the overall hearing outcome after surgical repair was favorable.OBJECTIVE The purpose of this study was to investigate etiological, clinical, and pathological characteristics of traumatic injuries of the middle ear ossicular chain and to evaluate hearing outcome after surgery. MATERIAL AND METHODS Thirty consecutive patients (31 ears) with traumatic ossicular injuries operated on between 2004 and 2015 in two tertiary referral otologic centers were retrospectively analyzed. Traumatic events, clinical features, ossicular lesions, treatment procedures, and audiometric results were evaluated. Air conduction (AC), bone conduction (BC), and air-bone gap (ABG) were analyzed preoperatively and postoperatively. Amsterdam Hearing Evaluation Plots (AHEPs) were used to visualize the individual hearing results. RESULTS The mean age at the moment of trauma was 27.9±17.1 years (range, 2-75 years) and the mean age at surgery was 33.2±16.3 years (range, 5-75 years). In 10 cases (32.3%), the injury occurred by a fall on the head and in 9 (29.0%) by a traffic accident. Isolated luxation of the incus was observed in 8 cases (25.8%). Dislocation of the stapes footplate was seen in 4 cases (12.9%). The postoperative ABG closure to within 10 and 20 dB was 30% and 76.7%, respectively. CONCLUSION Ossicular chain injury by direct or indirect trauma can provoke hearing loss, tinnitus, and vertigo. As injuries are heterogeneous, they require a tailored surgical approach. In this study, the overall hearing outcome after surgical repair was favorable.

Transient and steady state auditory responses with direct acoustic cochlear stimulation.

Objectives: Direct acoustic cochlear implants directly stimulate the cochlear fluid of the inner ear by means of a stapes piston driven by an actuator and show encouraging speech understanding in noise results for patients with severe to profound mixed hearing loss. Auditory evoked potentials recorded in such patients would allow for the objective evaluation of the aided auditory pathway. The aim of this study was (1) to develop a stimulation setup for EEG recordings in subjects with direct acoustic cochlear implants, (2) to show the feasibility of recording auditory brainstem responses (ABRs) and auditory steady state responses (ASSRs), and (3) to analyze the relation between electrophysiological thresholds derived from these responses and behavioral thresholds. Design: For the three subjects implanted during a phase Ib clinical study in the authors’ center, ABRs and 40 and 80 Hz ASSRs were recorded with a straightforward acoustic stimulation setup and a newly developed direct stimulation setup. Click trains with rates around 40 Hz and around 90 Hz were used as stimuli. By comparing amplitude growth function and phase delay in the same stimulus range, validity of the responses was confirmed. Results: With the acoustic stimulation setup, stimulation artifacts made it impossible to analyze responses. With the direct stimulation setup, stimulation artifacts could be removed completely and responses could be successfully recorded in a noninvasive manner in all subjects. Response properties such as ABR peak V latencies and ASSR apparent latencies were similar to those for acoustic stimulation, with apparent latencies of 39.9 and 24.7 msec for 40 and 90 Hz, respectively. Electrophysiological thresholds could be objectively determined from the ABRs and ASSRs. In the 40 Hz range, the mean difference between electrophysiological ASSR thresholds and behavioral ones was 12 dB. Conclusion: The results show that auditory evoked potential measurements with the developed direct stimulation setup are feasible and meaningful and should be further investigated to provide intraoperative feedback about the coupling of the actuator to the inner ear.

Measurement and Analysis of Feedback and Nonlinearities for the Codacs Direct Acoustic Cochlear Implant

Acoustic feedback is a very common problem in hearing instruments. Not only does it occur in common behind-the-ear or in-the-ear hearing aids, it also affects bone conduction implants, middle ear implants, and more recent devices, such as the direct acoustic cochlear implant (DACI). In this paper, we present the data and analysis relating to the feedback path characterization of the Cochlear™ Codacs™ DACI, performed on fresh frozen cadaver heads in four different measurement sessions. The general objectives were the following: 1) To measure and analyze the feedback path of the system and check for possible specimen-dependent variabilities; 2) To assess whether this feedback path is affected by an incorrect implantation; 3) To check for nonlinear behavior; and 4) To determine differences between tissular and airborne feedback. The data analysis reveals that the feedback seems to be dependent on the specific head morphology of the implanted specimen, and that an incorrect implantation might strongly affect the feedback path; additionally, the analysis reveals that some nonlinear behavior at high stimulus levels can be expected and, finally, that the feedback path is characterized by a tissular feedback component with a rather different frequency content compared to the airborne feedback component.