Maturation of Auditory Processing in Children With Dyslexia Compared to Average-reading Children

Study Overview
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Brief Summary
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The hypothesis of central auditory processing disorders has been advanced to explain the anomalies of the grapheme/phoneme combination in some dyslexia. These phonological disorders may be linked to abnormalities of the efferent (medial olivocochlear) system modulation and of cortical asymmetry. Indeed, the efferent system has an asymmetry in relation to handedness. Thus, in right-handed subject, it is predominant on the right side. In contrast, in the subject-handed dyslexic, the efferent system tends to be right-lateralized or non-lateralized. However, after an audio-visual training, normal lateralization can appear. This maturation of the efferent system lateralization during reading acquisition seems to have a particular profile in dyslexics with phonological disorder, especially if it is persistent. This finding allows to consider new prognostic evaluation and speech therapy rehabilitation in the dyslexic child.

Official Title
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Asymmetry, Auditory Processing and Reading Skills in Phonological Dyslexic Children Compared to Average-reading Children

Conditions
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Dyslexia

Intervention / Treatment
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* Other: no intervention


Participation Criteria
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Eligibility Criteria
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Common inclusion criteria Native French speaker and french education No medical treatment for behavior or neurological disorders (as epilepsy) Normal or corrected vision Right-handed children (Edinburgh tets (Oldfield, 1971): >+50%) Normal ORL examination No hearing loss : hearing thresholds not above 15 dB between 250 and 4 000 Hz Presence of Otoacoustic Emissions (Total amplitude < 5 dB or SNR > 3dB for at least 3 frequency bands between 1 and 4 kHz) Normal level of intellectual development Regular school attendance For the normal reading children Aged from 6 to less than 11 Normal reading level For the dyslexic children Aged from 8 to less than 11 Diagnostic of dyslexia made by a complet check-up during the 6 last months before the inclusion Exclusion Criteria Neurological or psychiatric disease incompatible with the testing procedure Ear disease during more than 6 months Normal reading children who have repeat a year Previous speech therapy for normal reading children Not corrected visual acuteness Schooling in a foreign language Foreign language spoken at home with both parents Known hearing deficit Invalid social security

Ages Eligible for Study
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Minimum Age: 6 Years
Maximum Age: 11 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Dyslexic children<br>Longitudinal follow-up without intervention | Other: no intervention<br> <br> |
| Normal reading children<br>Longitudinal follow-up without intervention | Other: no intervention<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of The Asymmetry Index of the efferent system at 2 years interval | The change of the Asymmetry Index of the efferent system The Asymmetry Index is the difference between the equivalent attenuation measured on the right ear and the left ear. Evoked otoacoustic emissions were recorded monaurally at five stimulus intensities ranging from 57 to 69 dB SPL in 3 dB steps, in random presentation order, with and without contralateral acoustic stimulation consisting of 30 dBSPL continuous broadband noise (speech-like noise) produced by an audiometer | Day 1 and then at least 2 years (± 4 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in the level of reading skill | Behavioral measure | Day 1 and then at least 2 years (± 4 weeks) | 
| Change in the percentage of correct answers obtained during a speech perception test in silence and noise. | Oral repetition of VCV | Day 1 and then at least 2 years (± 4 weeks) | 
| Change in percentage of correctly repeated stimuli which have been heard in both ears (binaural integration with divided attention) or in one indicated ear (binaural separation with selective attention) | Presentation of different speech material to both ears simultaneously | Day 1 and then at least 2 years (± 4 weeks) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Dyslexia, Medial olivocochlear system, Maturation, Auditory Processing