Preliminary observations on the development of auditory sensitivity in infants with Down syndrome

Behavioral Audiology Procedures in Children With Down Syndrome

Purpose Normative data regarding behavioral audiologic testing procedures are based upon the general population and often do not apply to children with Down syndrome (DS). Testing children with DS can be challenging, and outcomes may be unreliable due to their different cognitive demands and delays. The aim of this study was to assess optimal audiologic testing procedures for specific age groups of children with DS. Method This study used a retrospective investigation of 273 children with DS (145 boys, 128 girls; average age at evaluation = 5.92 ± 4.74 years) who received an audiologic evaluation during 2013 as part of their medical care at a large pediatric hospital (satellite facilities included). Results Age ranges for the completion of audiometry procedures in children with DS are provided. Average age to reliably complete behavioral testing in children with DS was delayed by up to 30 months compared to typically developing children. The majority of children with DS achieved at least good-to-fair reliability for audiologic results starting at 16 months (85.7%) and two ear results at 6-10 years (76.1%). Though not statistically significant, the use of a two-tester assistant compared to a single tester appeared to be helpful in obtaining reliable results. Conclusion The results provide a guide to optimal audiologic test procedures for children with DS, as the standard audiologic guidelines for typically developing infants and children do not apply.

Yes/no and two-interval forced-choice tasks with listener-based vs observer-based responses

Observer-based procedures are used to assess auditory behavior in infants, often incorporating adaptive tracking algorithms. These procedures are reliable, but effects of modifications made to accommodate infant testing are not fully understood. One modification is that observation intervals are undefined for the listener, introducing signal-temporal uncertainty and increasing the likelihood that listener response bias will influence estimates of performance. The effect of these factors was evaluated by comparing threshold estimates obtained from adults using two tasks: (1) single-interval, yes/no and (2) two-interval, forced-choice. Detection thresholds were estimated adaptively for a 1000-Hz FM tone in quiet and for a word presented in two-talker speech masking. Trials were initiated and judged by the observer (observer-based) or the listener (listener-based). Thus, listening intervals were temporally uncertain in observer-based procedures and temporally defined in listener-based procedures. Thresholds were higher for observer-based relative to corresponding listener-based procedures. The magnitude of this difference was similar across the yes/no and two-interval tasks, and was larger for masked word detection than tone detection in quiet. Listeners adopted a conservative criterion when tested using the observer-based, yes/no procedure, but modeling results suggest that signal-temporal uncertainty accounts for the largest portion of the threshold difference between observer-based and listener-based procedures.

Behavioral Assessment of Hearing in 2 to 4 Year-old Children: A Two-interval, Observer-based Procedure Using Conditioned Play-based Responses

Collecting reliable behavioral data from toddlers and preschoolers is challenging. As a result, there are significant gaps in our understanding of human auditory development for these age groups. This paper describes an observer-based procedure for measuring hearing sensitivity with a two-interval, two-alternative forced-choice paradigm. Young children are trained to perform a play-based, motor response (e.g., putting a block in a bucket) whenever they hear a target signal. An experimenter observes the child's behavior and makes a judgment about whether the signal was presented during the first or second observation interval; the experimenter is blinded to the true signal interval, so this judgment is based solely on the child's behavior. These procedures were used to test 2 to 4 year-olds (n = 33) with no known hearing problems. The signal was a 1,000 Hz warble tone presented in quiet, and the signal level was adjusted to estimate a threshold corresponding to 71%-correct detection. A valid threshold was obtained for 82% of children. These results indicate that the two-interval procedure is both feasible and reliable for use with toddlers and preschoolers. The two-interval, observer-based procedure described in this paper is a powerful tool for evaluating hearing in young children because it guards against response bias on the part of the experimenter.

Avaliação auditiva periférica em crianças com síndrome de Down

Objetivo Caracterizar o sistema auditivo periférico de indivíduos com síndrome de Down, por meio da audiometria convencional e de altas frequências. Métodos Estudo do tipo transversal e observacional. Participaram 15 indivíduos com síndrome de Down, de ambos os gêneros, entre 7 e 15 anos de idade. Foram realizados os seguintes procedimentos: Meatoscopia, Timpanometria com pesquisa do reflexo acústico ipsilateral e contralateral, Audiometria Tonal, Audiometria Vocal e Audiometria de Altas Frequências. Resultados Houve predomínio de perda auditiva condutiva de grau leve, em uma ou ambas as orelhas. As médias dos limiares auditivos para a audiometria convencional ficaram abaixo de 20 dBNA e, para a audiometria de altas frequências, ficaram entre 20 e 40 dBNA. O coeficiente de correlação de Pearson revelou correlação moderada positiva, entre os limiares de 9 a 14 kHz e a idade. Conclusão De forma geral, não foram observadas diferenças significativas, quando comparadas as orelhas direita e esquerda de indivíduos com síndrome de Down, na audiometria tonal, imitanciometria e logoaudiometria. A maioria das crianças apresentou alteração de orelha média e perda auditiva condutiva. A audiometria de altas frequências sugere o início de prejuízo da função coclear, que pode estar associado às otites médias frequentes e/ou à degeneração coclear precoce.

Reported sensory processing of children with Down syndrome

Investigators have identified delays and differences in cognitive, language, motor, and sensory development in children with Down syndrome (DS). The purpose of this study was to determine the parent-reported frequency of sensory processing issues in children with DS aged 3–10 years, and the parent-reported functional impact of those sensory issues. Parents completed the short sensory profile (SSP) and a parent questionnaire (PQ). SSP results revealed a total score definite difference rate of 49%. Highest rates of probable and definite difference were in the low energy/weak, underresponsive/seeks sensation, and auditory filtering subsections of the SSP. Themes were generated from responses on the PQ regarding the functional impact of sensory differences on occupational performance in their children with DS, and related strategies currently used by parents. Findings from the study provide information to parents and health care professionals regarding sensory processing patterns in children with DS, and provide foundational data for future research.

Otitis media in a mouse model for Down syndrome

The Ts65Dn mouse shares many phenotypic characteristics of human Down syndrome. Here, we report that otitis media, characterized by effusion in the middle ear and hearing loss, was prevalent in Ts65Dn mice. Of the 53 Ts65Dn mice tested, 81.1% had high auditory-evoked brainstem response (ABR) thresholds for at least one of the stimulus frequencies (click, 8 kHz, 16 kHz and 32 kHz), in at least one ear. The ABR thresholds were variable and showed no tendency toward increase with age, from 2 to 7 months of age. Observation of pathology in mice, aged 3-4 months, revealed middle ear effusion in 11 of 15 Ts65Dn mice examined, but only in two of 11 wild-type mice. The effusion in each mouse varied substantially in volume and inflammatory cell content. The middle ear mucosae were generally thickened and goblet cells were distributed with higher density in the epithelium of the middle ear cavity of Ts65Dn mice as compared with those of wild-type controls. Bacteria of pathogenic importance to humans also were identified in the Ts65Dn mice. This is the first report of otitis media in the Ts65Dn mouse as a model characteristic of human Down syndrome.

Auditory brainstem evoked responses in newborns with Down syndrome

Auditory brainstem evoked responses (ABRs) were compared in 15 newborns with Down syndrome and 15 sex-, age-, and weight-matched control newborns. Participants had normal ABRs based upon values specific to 32- to 42-weeks postconceptional age. Although Wave III and Wave V component latencies and the Wave I-III interpeak latency (IPL) were shorter in ABRs of infants with Down syndrome, the Wave III-V IPL was not, pointing to anomalies in the lower rather than upper brainstem auditory pathways. Shorter Down syndrome ABR latencies have been reported at many ages. Extending these findings to newborns suggests that the underlying basis for this develops prenatally. ABR patterns in infants with Down syndrome were similar to reports for intrauterine growth restricted newborns.

Down syndrome: caring holistically in primary health care

All primary health care should be underpinned with a firm theoretical knowledge. The holistic management of Down syndrome patients should be an integral part of this knowledge base. The application of this knowledge should ideally encompass a positive approach to empowering patients to lead healthy, active and normal lives. This article highlights a basic documentation of what 'Down syndrome' is. The article gives community nursing staff the opportunity to refresh their knowledge of the condition, then encourages critical reflection on professional practice within primary care, with the intention of raising skill and awareness for the holistic management of patients with Down syndrome.

Hörvermögen bei Kindern und Jugendlichen mit Down-Syndrom

BACKGROUND

There are controversial opinions about the incidence of hearing impairment of children and adolescents with Down's syndrome as an additional cause for obstruction in social and communicative live. Next to congenital diseases of the inner ear, functional limitations can often lead to conductive hearing disorders in patients with Down's syndrome.

PATIENTS AND METHODS

The hearing ability, otoscopic and audiometric characteristics of 115 patients aged 3.2+/-2.9 years were analysed retrospectively over 42 months.

RESULTS

A total of 86 children showed morphologic otoscopic peculiarities: transitory evoked otoacoustic emissions (TEOAE) were often non-reproducible, even in patients with normal hearing abilities(14.1% of cases), and were not evaluable in 32.8% of cases. Half of the patients showed hearing loss, 82% of whom suffered from a conductive hearing loss, 6.9% from a combined, and 8.6% from isolated sensorineural hearing loss. Hearing loss was first diagnosed when the children were 4.6+/-3.4 years old.

CONCLUSION

The frequent occurrence of hearing loss justifies and requires an early and continuous pedaudiological examination. As a common screening examination, TEOAE is limited due to its cost, however, it fulfils its purpose as a means of distinguishing healthy children from those with possible hearing disorders. In most cases, objective and subjective audiometric methods must be combined in order to precisely define the hearing ability.

Sensory evoked potentials in infants with Down syndrome

AIM

To investigate the sensory functions of the peripheral to central pathways in infants with Down syndrome (DS) by sensory evoked potentials.

METHODS

Fifty-five infants, 30 DS infants and 25 controls, were examined by multimodal evoked potentials, including brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP) and short-latency somatosensory evoked potentials (SSEP).

RESULTS

No obvious difference was found in the peak latencies between the two groups for BAEP. Nine children with DS showed abnormal BAEP; six had hearing loss and three had prolonged wave I latencies. For VEP, the peak latencies of P(2) and N(2) were significantly longer and the amplitudes were smaller in the DS group than in the control group. Of the 30 infants with DS, five had significantly prolonged P(2) latencies and two had lower amplitudes. In SSEP, the mean latencies of N(20) and the interpeak latencies of N(13)-N(20) of the infants with DS showed apparent prolongation compared to the controls. Seven of 30 (23.3%) DS patients had prolonged N(20) latencies.

CONCLUSION

Our results indicate that various sensory deficits occur in patients with DS during the first year of life.

Exploratory activity and motor coordination in wild-type SOD1/SOD1 transgenic mice

SOD1 is one of several overexpressed genes in trisomy 21. In order to dissect possible genetic causes of the syndrome, wild-type SOD1/SOD1 transgenic mice were compared to FVB/N non-transgenic controls at 5 months of age in tests of exploratory activity and motor coordination. Wild-type SOD1/SOD1 transgenic mice had fewer stereotyped movements in an open-field and fell sooner from a rotorod than controls. In contrast, wild-type SOD1/SOD1 transgenic mice had fewer falls on a wire suspension test. There was no intergroup difference for ambulatory movements in the open-field, exploration of the elevated plus-maze, emergence from a small compartment, and motor coordination on a stationary beam. These results indicate that homozygous mice expressing human SOD1 are impaired in their ability to adjust their posture in response to a moving surface and make fewer small-amplitude movements without any change in general exploratory activity.

Characterization of hemizygous SOD1/wild-type transgenic mice with the SHIRPA primary screen and tests of sensorimotor function and anxiety

SOD1 is one of several overexpressed genes in Down's syndrome. In order to dissect genetic causes of the syndrome, hemizygous human wild-type SOD1 transgenic mice were compared to FVB/N non-transgenic controls at 3 months of age in the SHIRPA primary screen of neurologic function as well as in tests of motor activity and coordination. The responsiveness of SOD1/wt transgenic mice to visual and somatosensory stimuli was reduced in placing, pinna, corneal, and toe-pinch tests. In addition, SOD1/wt transgenic mice crossed fewer segments on a stationary beam. On the contrary, there was no intergroup difference for motor activity and anxiety in open-field and emergence tests and for latencies before falling on the stationary beam, coat-hanger, and rotorod. These results indicate mild deficits in sensorimotor responsiveness in a mouse model expressing human SOD1 and that the overexpressed gene may be responsible for some Down symptoms.

Percepção da fala em bebês no primeiro ano de vida

A fala humana é um som de grande complexidade, cujo processamento perceptual, produção e relações com a linguagem e a cognição necessitam de uma análise integrada, tanto do ponto de vista do conhecimento disponível como também das especificidades metodológicas. Neste artigo faz-se uma breve revisão da literatura sobre as principais aquisições e desenvolvimento da linguagem no primeiro ano de vida de bebês com desenvolvimento normal com enfoque na percepção da fala humana. Busca-se, também, analisar a ocorrência de distúrbios auditivos que podem causar alterações na percepção da fala, com possíveis implicações para o desenvolvimento pré-lingüístico. Atenção especial é dada ao desenvolvimento da habilidade de percepção de fala e de linguagem em bebês com síndrome de Down. É analisada a predisposição, nesta população, a problemas audiológicos, sua relação com alterações no desenvolvimento de linguagem, e a tendência apresentada no primeiro ano de vida para padrões diferenciados de atenção à fala.