Dyslexia
Conditions
Keywords
Dyslexia, Medial olivocochlear system, Maturation, Auditory Processing
Brief summary
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.
Interventions
OTHERno intervention
Sponsors
Hospices Civils de Lyon
Study design
Observational model
CASE_CONTROL
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
6 Years to 11 Years
Healthy volunteers
Yes
Inclusion criteria
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change of The Asymmetry Index of the efferent system at 2 years interval | Day 1 and then at least 2 years (± 4 weeks) | 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in the level of reading skill | Day 1 and then at least 2 years (± 4 weeks) | Behavioral measure |
| Change in the percentage of correct answers obtained during a speech perception test in silence and noise. | Day 1 and then at least 2 years (± 4 weeks) | Oral repetition of VCV |
| 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) | Day 1 and then at least 2 years (± 4 weeks) | Presentation of different speech material to both ears simultaneously |
Countries
France
Outcome results
None listed