The effects of Phoniatric PREhabilitation in Head and Neck Cancer patients on Aspiration and Preservation of Swallowing (PREHAPS): study protocol of a monocentric prospective randomized interventional outcome-blinded trial.

BACKGROUND: Dysphagia, with its negative impact on life expectancy and quality of life, is a major side effect of head and neck squamous cell carcinoma (HNSCC). In a typical Head and Neck Cancer Center, more than half of patients are affected. Improving treatment, and ideally prevention respectively prehabilitation, therefore seems more than desirable. METHODS: The study is planned as a monocentric, prospective, outcome-blinded, randomized interventional study comparing an advanced phoniatric-logopedic prehabilitation with a control (standard of care). Seventy patients (30 control group, 30 intervention group, 10 drop-out rate of 15%) with an initial diagnosis of invasive HNSCC and curative treatment intention will be included over a period of 17 months. In addition to the previous standard, both groups will undergo both detailed subjective assessment of swallowing function and quality of life by means of various questionnaires and objective analyses by bioelectrical impedance measurements and phoniatric endoscopic swallowing examinations. In the intervention group, risk-related nutritional counseling (face-to-face) and phoniatric-logopedic prehabilitation are provided: detailed counseling with video demonstration and exercises to strengthen and improve the range of motion of the oral, pharyngeal, and laryngeal muscles (guided by exercise diary). Controls are performed at 6 weeks, 3 and 6 months, and 9 or 12 months after the end of therapy during the regular tumor follow-up. Primary study endpoints are swallowing function and emotional distress at 6 weeks of control visit. DISCUSSION: Prehabilitation measures have already proven successful in other patient groups, e.g., transplant patients. In the field of head and neck oncology, interest in such concepts has increased significantly in recent years. However, usually, only subgroups, e.g., patients with swallowing problems after radiochemotherapy alone, are in focus. Our study aims to investigate the general benefit of prehabilitation with regard to swallowing function, which is so important for protection of aspiration and quality of life. TRIAL REGISTRATION: German Clinical Trials Register DRKS00029676 . International Clinical Trials Registry Platform DRKS00029676 . Registered on 19 July 2022.

Burden of sequelae and healthcare resource utilization in the first year of life in infants born with congenital cytomegalovirus (cCMV) infection in Germany: A retrospective statutory health insurance claims database analysis.

BACKGROUND: Congenital cytomegalovirus (cCMV) infection can have a broad range of manifestations. This study aimed to assess cCMV-associated sequelae and healthcare resource utilization (HCRU) in infants during the first year of life in Germany. METHODS: A retrospective, controlled cohort study using German claims data from the Institute for Applied Health Research Berlin (InGef) database was conducted. cCMV-associated sequelae and HCRU during the first year of life were assessed by matching (1:60) infants with at least one inpatient/outpatient cCMV diagnosis (ICD-10-GM: P35.1) ≤90 days after birth (cCMV90 cohort) and infants with at least one inpatient cCMV diagnosis plus specific sequelae ≤21 days after birth (cCMV21-S) to infants without cCMV or CMV (ICD-10-GM: B25) diagnosis (control group), respectively. Outcomes were analyzed during the first 365 days of life. RESULTS: Between 2014-2018, we identified 54 newborns for cCMV90 and 24 newborns for cCMV21-S cohort. Compared to the 3,240 and 1,440 controls, respectively, more cCMV90 infants (83.3% vs. 41.9%, p<0.01) presented with at least one sequela during the first year of life, including intrauterine growth retardation (42.6% vs. 5.3%, p<0.01), sensorineural hearing loss (SNHL) to deafness (38.9% vs. 2.2%, p<0.01), and motor development disorders (33.3% vs. 10.9%, p<0.01). Further, 13.0% of cCMV90 infants (vs. 2.3%, p<0.01) suffered from visual impairment. In cCMV21-S cohort, intrauterine growth retardation (79.2% vs. 6.0%, p<0.01), prematurity (54.2% vs. 7.3%, p<0.01), and motor development disorders (50.0% vs. 11.0%, p<0.01) were the most frequent sequelae. Infants in the cCMV90 and cCMV21-S cohort had, on average, 7.3 times and 9.5 times more hospitalizations and 2.0 times and 2.1 times more outpatient physician visits than their respective controls (p<0.01). Hospitalized infants with cCMV stayed, on average, significantly longer in hospital compared to their controls (cCMV90 cohort: 30.3 days vs. 9.0 days, p<0.01; cCMV21-S cohort: 46.5 days vs. 9.3 days, p<0.01). CONCLUSIONS: cCMV-infection shows a considerable disease and healthcare burden during the first year of life. More than 80% of the identified newborns with cCMV suffered from at least one associated sequela during the first year of life, including long-term sequelae such as SNHL (40%) and visual impairment (13%). Additional steps for prevention of cCMV infection and associated sequelae as well as a comprehensive monitoring of disease burden are needed.

Elective Tracheotomy in Patients Receiving Mandibular Reconstructions: Reduced Postoperative Ventilation Time and Lower Incidence of Hospital-Acquired Pneumonia.

Elective tracheotomy (ET) secures the airway and prevents adverse airway-related events as unplanned secondary tracheotomy (UT), prolonged ventilation (PPV) or nosocomial infection. The primary objective of this study was to identify factors predisposing for airway complications after reconstructive lower ja surgery. We reviewed records of patients undergoing mandibulectomy and microvascular bone reconstruction (N = 123). Epidemiological factors, modus of tracheotomy regarding ET and UT, postoperative ventilation time and occurrence of hospital-acquired pneumonia HAP were recorded. Predictors for PPV and HAP, ET and UT were identified. A total of 82 (66.7%) patients underwent tracheotomy of which 12 (14.6%) were performed as UT. A total of 52 (42.3%) patients presented PPV, while 19 (15.4%) developed HAP. Increased operation time (OR 1.004, p = 0.005) and a difficult airway (OR 2.869, p = 0.02) were predictors, while ET reduced incidence of PPV (OR 0.054, p = 0.006). A difficult airway (OR 4.711, p = 0.03) and postoperative delirium (OR 6.761, p = 0.01) increased UT performance. HAP increased with anesthesia induction time (OR 1.268, p = 0.001) and length in ICU (OR 1.039, p = 0.009) while decreasing in ET group (HR 0.32, p = 0.02). OR for ET increased with mounting CCI (OR 1.462, p = 0.002) and preoperative radiotherapy (OR 2.8, p = 0.018). ET should be strongly considered in patients with increased CCI, preoperative radiotherapy and prolonged operation time. ET shortened postoperative ventilation time and reduced HAP.

Healthcare costs of congenital cytomegalovirus (cCMV) disease in infants during the first two years of life: a retrospective German claims database analysis.

BACKGROUND: Congenital cytomegalovirus (cCMV) infection can cause severe neurological damage, growth retardation, hearing loss, and microcephaly in infants. We aimed at assessing healthcare costs of infants with recorded cCMV diagnosis in an administrative claims database in the first 2 years of life. METHODS: We conducted a retrospective, controlled cohort study using German claims data from the Institute for Applied Health Research Berlin (InGef) database. Incremental healthcare costs during the first and second year of life were assessed by matching (1:60) infants with cCMV diagnoses ≤ 90 days after birth (cCMV90 cohort) to infants without cCMV diagnosis ("representative" controls) and infants with cCMV diagnoses ≤ 21 days after birth plus specific symptoms (cCMV21-S) to infants without cCMV and any ICD-10-GM records (besides Z00-Z99) until 4th preventive health check-up ("healthy" controls). Due to missing data, mean imputation was applied for aids and remedies costs. RESULTS: We identified 54 and 24 infants born 2014-2018 for the cCMV90 and cCMV21-S cohorts, respectively. During the first year, mean (median) healthcare costs were significantly higher in cCMV90 cases vs. "representative" controls (€22,737 (€9759) vs. €3091 (€863), p < 0.001), with 87.2% inpatient costs. Healthcare costs for cCMV21-S cases compared to "healthy" controls were €34,498 (€20,924) vs. €680 (€569), p < 0.001. Differences decreased for both comparisons in the second year but remained statistically significant. CONCLUSIONS: cCMV comprises a considerable economic burden for the German healthcare system (€19,646 to €33,818 higher mean costs for infants with recorded cCMV diagnosis in the first year of life). Attempts should be made to reduce this burden.

Prehabilitation of dysphagia in the therapy of head and neck cancer- a systematic review of the literature and evidence evaluation.

Background: Prehabilitation is becoming increasingly important in oncology because of the significant survival benefits that the reduction of malnutrition provide. Specifically, tumor- and therapy-related dysphagia leads to malnutrition in more than half of head and neck tumor patients. Studies describe the positive effects of an early onset of swallow-specific prehabilitation on the protection of the swallowing function. This paper intents to evaluate the existing evidence on the efficacy of preventive forms of swallowing therapy. Methods: A systematic literature search was performed in February 2022 in the Cochrane Library, MEDLINE via PubMed, and ClinicalTrials.gov databases for randomized controlled trials investigating preventive swallowing therapy in head and neck tumor patients. This Procedure complies with the PRISMA statement. The RCTs were evaluated by using the PEDro Scale and the Cochrane Risk of Bias tool RoB2. Results: Five randomized-controlled trials with 423 participants were identified. Four Studies showed moderate to high quality in the PEDro analysis, one showed less. The risk of bias was high in all studies because there was no possibility for blinding and there were high dropout rates. Heterogeneity in interventions, measurement instruments, measurement time points, and outcomes limits a general statement about which swallowing exercises are suitable for the prevention of dysphagia in head and neck tumor patients. Evidence is provided for short-term effects (≤24 months) on functional aspects of swallowing and quality of life. Overall, a decreasing adherence over time was observed in the intervention groups. Discussion: Initial studies describe swallowing-specific prehabilitation programs in head and neck tumor patients as effective, at least in the short term, whereas long-term effects need to be further investigated. At the current time the evidence base for clear recommendations does not appear to be sufficiently high and studies share a high risk of bias. Further well-designed research, especially considering the conditions in the national health care system, is needed. Other: There was no funding and no registration.

A clinical comparison of DPOAE fine structure reduction methods.

OBJECTIVE: To evaluate two real-time methods for reducing distortion product otoacoustic emission (DPOAE) fine structure in terms of DPOAE amplitude and fine structure depth. DESIGN: A prospective, repeated-measures design was used to assess DPOAE characteristics in response to a conventional stimulation method (Conv.), as well as for methods implementing either a generic suppressor tone (Supp.) or frequency modulation of the f2 primary tone (FM). STUDY SAMPLE: Eighty-three young adults (58 females) between the ages of 20 and 34 years with normal hearing completed testing for this study. RESULTS: Use of the Conv. and FM methods resulted in consistently higher DPOAE levels relative to the Supp. method, with average advantages of 6 and 5 dB, respectively. For all methods, increased fine structure depth was observed for stimulation with lower level (25-45 dB SPL) and lower frequency (1000-3000 Hz) primary tones. Finally, use of the Supp. and FM methods resulted in significantly decreased fine structure depth relative to the Conv. method. CONCLUSION: Through frequency modulation of the f2 primary tone, it was possible to reduce the depth of fine structure across a clinically meaningful range of stimulation levels and frequencies without concomitant reduction in DPOAE amplitude.

Subclinical conductive hearing loss significantly reduces otoacoustic emission amplitude: Implications for test performance.

OBJECTIVES: Distortion product otoacoustic emissions (DPOAEs) are a time-efficient, non-invasive means of assessing the integrity of active inner ear mechanics. Unfortunately, the presence of even relatively minor conductive hearing loss (CHL) has been suggested to reduce the clinical utility of DPOAEs significantly. The primary aims of this study were to systematically evaluate the impact of CHL on DPOAE amplitude and to determine if ear-specific primary tone level manipulations can be used to mitigate CHL impact and recover DPOAE measurability. METHODS: For 30 young adults (57 ears) with normal hearing, DPOAEs were obtained for f2 = 1-6 kHz. Observed DPOAE amplitudes were used to generate ear- and frequency-specific models with the primary tone levels, L1 and L2, as inputs and predicted DPOAE amplitude, LDP, as output. These models were then used to simulate the effect of CHL (0-15 dB), as well as L1 manipulations (0-15 dB), on DPOAE measurability. RESULTS: Mean LDP for every CHL condition was significantly different from that for all other conditions (p = <.001), with a mean LDP attenuation of 8.7 dB for every 5 dB increase in CHL. Mean DPOAE measurability in response to a standard clinical stimulation paradigm of L1/L2 = 65/55 (dB SPL) was determined to be 99%, 84%, 37%, and 9% in the presence of 0, 5, 10, and 15 dB CHL, respectively. In the presence of 10 dB CHL, altering L1 resulted in an approximately 25% increase in DPOAE responses. CONCLUSION: Subclinical CHL loss is sufficient to significantly impair DPOAE measurability in a meaningful proportion of otherwise healthy ears. However, through strategic alteration of primary tone levels, the clinician can mitigate CHL impact and at least partially recover DPOAE measurability.

Wideband Absorbance and 226-Hz Tympanometry in the Prediction of Optimal Distortion Product Otoacoustic Emission Primary Tone Levels.

PURPOSE: Distortion product otoacoustic emission (DPOAE) amplitude is sensitive to the primary tone level separation effective within the cochlea. Despite potential for middle ear sound transmission characteristics to affect this separation, no primary tone level optimization formula accounts for its influence. This study was conducted to determine if inclusion of ear- and frequency-specific immittance features improves primary tone level optimization formula performance beyond that achieved using a univariate, L2-based formula. METHOD: For 30 adults with normal hearing, DPOAE, wideband absorbance, and 226-Hz tympanometry measures were completed. A mixed linear modeling technique, incorporating both primary tone and acoustic immittance features, was used to generate a multivariable formula for the middle ear-specific recommendation of primary tone level separations for f2 = 1-6 kHz. The accuracy with which L1OPT, or the L1 observed to maximize DPOAE level for each given L2, could be predicted using the multivariable formula was then compared with that of a traditional, L2-based univariate formula for each individual ear. RESULTS: Use of the multivariable formula L1 = 0.47L2 + 2.40A + f2param + 38 [dB SPL] resulted in significantly more accurate L1OPT predictions than did the univariate formula L1 = 0.49L2 + 41 [dB SPL]. Although average improvement was small, meaningful improvements were identified within individual ears, especially for f2 = 1 and 6 kHz. CONCLUSION: Incorporation of a wideband absorbance measure into a primary tone level optimization formula resulted in a minor average improvement in L1OPT prediction accuracy when compared with a traditional univariate optimization formula. Further research is needed to identify characteristics of ears that might disproportionately benefit from the additional measure.

[A new atraumatic device for liposuction and injection represents a technical advance for primary fat injection after cordectomy]. / Neues Verfahren zur Liposuktion und Fettaugmentation nach Chordektomie.

Lipoinjections into the vocal folds are well established in otorhinolaryngology. Currently, lipofilling in patients with surgical defects after laser cordectomy is discussed. We describe a new device for liposuction and lipofilling for primary vocal fold reconstruction after laser cordectomy. A patient with a surgical defect after pT1a glottic cancer is presented. Primary lipoinjection after laser cordectomy was documented as a safe and easy method to reconstruct the surgical defect. No relevant complications have been observed.

Potential Benefit of Selective CMV Testing after Failed Newborn Hearing Screening.

Evidence-based guidelines for the prevention, diagnosis and treatment of congenital cytomegalovirus (cCMV) were recently released by two independent expert groups. Of particular emphasis was the relationship between cCMV and sensorineural hearing loss (SNHL), a major component of the virus' overall disease burden. In this study, a literature review was performed to estimate the proportion of cCMV-related SNHL cases, which might be identified through selective cCMV testing following failed newborn hearing screening. Furthermore, it was of interest to estimate the potential benefit of emerging antiviral therapies. Currently, at most 10% of cCMV-related SNHL is likely to be identified clinically. Through use of a selective cCMV testing protocol, however, a significant improvement in the identification rate can be achieved. Recent expert group statements strongly recommend antiviral therapy in cases of moderate-to-severe disease, especially in the presence of central nervous system involvement. Though differences exist between recommendations in instances of isolated SNHL or SNHL in combination with only mild symptoms, the majority of experts in both groups offered at least a weak recommendation for antiviral treatment. Available results suggest antiviral treatment could therefore benefit a meaningful proportion of newborns referred for cCMV testing following failed newborn hearing screening.

Estimation of Minor Conductive Hearing Loss in Humans Using Distortion Product Otoacoustic Emissions.

OBJECTIVES: Conductive hearing loss (CHL) systematically alters distortion product otoacoustic emission (DPOAE) levels through attenuation of both the primary tones and the evoked response by the middle ear, as well as through modification of the effective L1-L2 relationship within the cochlea. It has been postulated that, if optimal primary tone level relationships for an ear without CHL are known or can be estimated accurately and a CHL can be presumed to attenuate both primary tones to a similar extent, the adjustment to L1 required to restore an optimal L1-L2 separation following CHL induction can be utilized to estimate CHL magnitude objectively. The primary aim of this study was to assess the feasibility of objectively estimating experimentally produced CHL in humans by comparing CHL estimates resulting from DPOAE- and pure-tone audiometry-based methods. A secondary aim was to compare the accuracy of DPOAE-based CHL estimates when obtained using generic, as opposed to ear-specific, optimal primary tone level formula parameters. DESIGN: For a single ear of 30 adults with normal hearing, auditory threshold for a 1 kHz tone was obtained using automated Békésy audiometry at an ear-canal pressure of 0 daPa, as well as at a negative pressure sufficient for increasing threshold by 3 to 10 dB. The difference in threshold for the ear-canal pressure conditions was defined as the pure-tone audiometry-based estimate of CHL (CHLPT). For the same two ear-canal pressures, optimal DPOAE primary tone level relationships were identified for f2 = 1 kHz. Specifically, for 20 ≤ L2 ≤ 70 dB SPL, L1 was varied 15 dB above and below the recommendation of L1 = 0.49 L2 + 41 (dB SPL). The difference between the optimal L1-L2 relationships for the two pressure conditions was defined as ΔL1OPT. A DPOAE-based estimate of CHL (CHLDP) was obtained using the formula CHLDP = ΔL1OPT/(1 - a), where a represents the slope of the optimal L1-L2 relationship observed in the absence of CHL. RESULTS: A highly significant linear dependence was identified between pure-tone audiometry- and DPOAE-based estimates of CHL, r(19) = 0.71, p < 0.001. However, the correlation was only significant when ear-specific optimization formula parameters were known. Use of generic, frequency-nonspecific parameters resulted in significantly less accurate estimates than did either ear-specific (p < 0.001) or generic, frequency-specific parameters (p = 0.007). CONCLUSIONS: This study provides empirical support for a theory of how CHL, through a combination of middle ear filtering and alteration of effective primary tone level relationships within the cochlea, systematically affects DPOAE amplitude. Although CHLDP was shown to be significantly predictive of CHLPT when optimization formula parameters for a given ear, both with and without mild CHL, were known, the lack of a meaningful relationship when using generic primary tone level formula parameters significantly limits the method's potential for clinical utility.

Average optimal DPOAE primary tone levels in normal-hearing adults.

OBJECTIVE: Despite great progress towards optimizing DPOAE primary tone characteristics, factors such as stimulus and intra-subject emission variability have not been addressed. The purpose of this study was to identify optimal primary tone level relationships when these sources of variability were acknowledged, and to identify any influences of test frequency. DESIGN: Following coupler-based measurements assessing primary tone level stability, two experiments were conducted. In experiment 1, DPOAE test-retest reliability without probe replacement was measured for f2 = 1-6 kHz with L1 = L2 = 65 dB SPL. In experiment 2, optimal L1-L2 relationships were identified for f2 = 1-6 kHz. For 20 ≤ L2 ≤ 75 dB SPL, L1 was varied 15 dB SPL above and below the recommendation of L1 = 0.4 L2 + 39 [dB SPL]. STUDY SAMPLE: Eleven normal-hearing adults participated in experiment 1. Thirty normal-hearing adults participated in experiment 2. RESULTS: Stimulus variability did not exceed 0.1 dB SPL. DPOAE reliability testing revealed an across-frequency mean standard error of measurement of 0.52 dB SPL. The average optimal L1-L2 relationship was described by L1 = 0.49 L2 + 41 [dB SPL]. A significant effect of frequency was identified for 6 kHz. CONCLUSION: Including relevant sources of variability improves internal validity of a primary tone level optimization formula.

Load Measurement on Foundations of Rockfall Protection Systems.

Rockfall protection barriers are connected to the ground using steel cables fixed with anchors and foundations for the steel posts. It is common practice to measure the forces in the cables, while to date measurements of forces in the foundations have been inadequately resolved. An overview is presented of existing methods to measure the loads on the post foundations of rockfall protection barriers. Addressing some of the inadequacies of existing approaches, a novel sensor unit is presented that is able to capture the forces acting on post foundations in all six degrees of freedom. The sensor unit consists of four triaxial force sensors placed between two steel plates. To correctly convert the measurements into the directional forces acting on the foundation a special in-situ calibration procedure is proposed that delivers a corresponding conversion matrix.

Influence of the individual DPOAE growth behavior on DPOAE level variations caused by conductive hearing loss and elevated intracranial pressure.

OBJECTIVES: Minor conductive hearing loss (CHL) can compromise the evaluation of the inner ear function with distortion product otoacoustic emissions (DPOAE). Elevation of the intracranial pressure (ICP) is also expected to alter the middle ear (ME) sound transmission. An impaired ME sound transmission leads to an attenuation of the DPOAE primary tone levels (L1 and L2) during forward transmission and of DPOAE levels (LDP) during backward transmission. The effect of the attenuation of L1 and L2 is complex and might have unexpected effects on DPOAE levels. In this work, CHL- and ICP-induced alterations of LDP versus L1 growth functions (constant L2 and increasing L1) are investigated. The first aim of this study is to explain how alterations of ME sound transmission can affect DPOAEs and to characterize the dependency of DPOAE level alterations on L2,L1 combinations and on the individual shape of LDP versus L1 growth functions. The second aim is to identify analogies between CHL- and ICP-induced alterations of DPOAEs and to discuss implications for a potential noninvasive ICP monitoring. DESIGN: This study focuses on general theoretical considerations, supported by selected experimental observations in different species and simulations. DPOAEs were measured in guinea pigs before and after induction of a CHL (1 ear) and during increased ICP (1 ear), and in humans during changes of the postural position to alter the ICP (4 ears). RESULTS: In both CHL and elevated ICP, DPOAE levels are not only reduced, but LDP versus L1 growth functions exhibit a shift to higher L1. The absolute DPOAE level alterations strongly depend on the L2,L1 combinations and the individual shape of the LDP versus L1 growth functions. In steeper LDP versus L1 growth functions, the DPOAE level alterations exhibit a larger variation. DPOAE levels can even increase. The largest variation can be found in ears with a nonmonotonic DPOAE growth behavior. An example of a guinea pig ear is presented with a nonmonotonic DPOAE growth behavior and a CHL of 4 dB, where the DPOAE level alterations varied between -32 and +9 dB depending on L1. CONCLUSIONS: The data enable a more comprehensive view of DPOAE level alterations during CHL and elevated ICP. The observations also explain the problem that DPOAE and ICP alterations do not correlate linearly. An evaluation of the shift of the LDP versus L1 growth function along the L1 axis provides a potential tool to improve both the assessment of the inner ear function in the presence of a CHL and noninvasive ICP monitoring with DPOAEs.

Effects of botulinum toxin a on cytokine synthesis in a cell culture model of cutaneous scarring.

OBJECTIVE: To evaluate possible botulinum toxin A effects in a cell culture model. METHODS: In a cell culture model with dermal fibroblasts and microvascular endothelial cells, possible botulinum toxin A effects were evaluated. Cell proliferation and cytokine expression were analyzed using viability assays and enzyme-linked immunosorbent assay techniques. RESULTS: Neither cell proliferation nor cytokines and growth factors (interleukin 6, monocyte chemoattractant protein 2, fibroblast growth factor, macrophage colony-stimulating factor, and vascular endothelial growth factor) were affected by botulinum toxin A incubation. CONCLUSIONS: The present data do not add evidence to suggest a significant therapeutic role of botulinum toxin A injections for cutaneous wound healing beyond chemoimmobilization. Further studies that include patient-specific cells of hypertrophic scars are required to better understand what role botulinum toxin A can play in the treatment of mature scar tissue.

Quantitative estimation of minor conductive hearing loss with distortion product otoacoustic emissions in the guinea pig.

Subclinical conductive hearing losses (CHLs) can affect otoacoustic emissions and therefore limit their potential in the assessment of the cochlear function. Theoretical considerations to estimate a minor CHL from DPOAE measurements [Kummer et al. (2006). HNO 54, 457-467] are evaluated experimentally. They are based on the fact, that the level difference of the stimulus tones L(1) and L(2) for optimal excitation of the inner ear is given by L(1)=aL(2)+b. A CHL is presumed to attenuate both L(1) and L(2) to the same extent such that excitation of the inner ear is no longer optimal. From the change of L(1) that is necessary to restore optimal excitation of the inner ear and thus to produce maximal DPOAE levels, the CHL can be estimated. In 10 guinea pig ears an experimental CHL was produced, quantified by determination of compound action potential (CAP) thresholds at 8 kHz (CHL(CAP)) and estimated from DPOAE measurements at 8 kHz (CHL(DPOAE)). CHLs up to 12 dB could be assessed. CHL(DPOAE) correlated well with CHL(CAP) (R=0.741, p=0.0142). Mean difference between CHL(DPOAE) and CHL(CAP) was 4.2±2.6 dB. Estimation of minor CHL from DPOAE measurements might help to increase the diagnostic value of DPOAEs.

Correlation between psychometric tests and mismatch negativity in preschool children.

The objective was to determine whether mismatch negativity (MMN) is suitable to supplement subjective psychometric subtests of central hearing. We assessed 13 healthy children and 32 children with central auditory processing disorder (CAPD). Three different types of sound deviants were presented in a multi-deviant MMN design. At group level, the incidence of MMN was always higher in clinically diagnosed controls. Children with better results in the subtest Auditory Memory Span had a higher incidence of MMN. The controls also had peak latencies that occurred significantly earlier in frontal, central and temporal electrode sites. The area under the curve (AUC) displayed an asymmetric distribution in CAPD children, who tended to have a left-hemispheric dominance. AUC, peak latency, and the incidence of MMN reflected the discriminative ability of CAPD children. Hence, these characteristics could be used for investigating children with deficits in central hearing and can supplement psychometric tests.

Statistical detection and analysis of mismatch negativity derived by a multi-deviant design from normal hearing children.

To shorten the time of measurement of mismatch negativity (MMN) and to objectify the analysis of MMN characteristics, auditory evoked potentials (AEP) were recorded and MMNs were statistically examined. AEPs from 16 healthy children between the ages of 5 and 7 were elicited using a multi-deviant design including: frequency, duration, intensity, and gap. For detection of MMN an automatic method was applied based on statistical analysis (t-tests) of AEP sweeps. The incidences found were compared to the incidences of MMNs detected by visual inspection of difference waveforms. MMN features such as peak amplitude, peak latency, onset latency, duration of MMN, and area under the curve were evaluated for MMN intervals identified by statistical analysis. MMN incidences identified by statistical analysis (44) reflected a consistency of 84% to visually identified (52) incidences of MMN. Scalp distribution of MMN was mainly fronto-central. Peak latencies of the duration MMN differed significantly from those of the other deviant MMNs. The multi-deviant paradigm was successfully applied for measuring children's AEPs. The statistical approach proved applicable for analysing the data objectively.

Cortical auditory evoked potentials to acoustic changes in speech stimuli in children.

OBJECTIVE: To compare the maturation of speech-evoked N170 components of cortical auditory evoked potentials with that of tone-evoked N1 components. PATIENTS AND METHODS: Cortical auditory evoked potentials to speech and tone stimuli were derived in 42 children from age 4 to 14 years. The N170 was derived from the difference curve of responses to monosyllabic words with initial consonant-to-vowel transitions and their intensity-equivalent noise signals. RESULTS: The incidence of N1 increased from 71% below age 9 to 91% above, that of N170 tended to increase from 40 to 67% above. From age 9, adult-like morphologies of the difference waveforms were found and the time constants of N1 and N170 latency maturation were nearly identical. CONCLUSION: The N170 component is interpreted as a response to speech-specific acoustic changes such as the consonant-vowel transition. The late appearance of N170 indicates an electrophysiological correlate of speech perception that continues to develop into adolescence. Its clinical application, however, is limited due to the low incidence of N170.

Wavelet-based analysis of MMN responses in children.

Event-related potentials (ERPs) as part of the EEG are applied to assess auditory processing in children. Mismatch negativity (MMN) is a change-specific component of ERPs that indicates a pre-cognitive discrimination process. MMN responses were recorded in 10 healthy preschool children to four different types of signal changes. The signals investigated were processed using a discrete wavelet transform (DWT) to analyze the characteristics of the ERP components. All children showed distinct MMN that was significant in all tasks. The MMN amplitudes varied between subjects and depended on the different tasks. The wavelet transform allowed simplified analysis and quantification of the MMN component, as well as the double-peak structure of the P1 component. The variation in MMN amplitudes suggests the possibility of determining individual auditory profiles. Owing to the shorter time required, the MMN paradigm suggested combined with the DWT proposed offers a new objective investigation method for children.