Introduction:
The acquisition of written code is a complex activity requiring explicit learning of the relationships between written words and spoken words. Although a large majority of children learn to read with time and specific instruction, some children face significant and lasting difficulties in acquiring the child: about 25% of schoolchildren would not have sufficient reading skills to Understand the written texts and thus develop their knowledge. Among these failing readers, a small number have a specific cognitive impairment that prevents them from acquiring the deciphering mechanisms required for reading. These children, qualified as dyslexics, would represent between 3% and 6% of school children.
One of the first clinical descriptions of developmental dyslexia is due to the English physician Pringle-Morgan; One of his patients was a 14-year-old boy of brilliant intelligence but totally unable to read and write. Pringle-Morgan compares this case to those of adults with reading disorders after brain injury and publishes it in the British Medical Journal. Hinshelwood Ophthalmologist later became enthusiastic about this problem and in 1917 published a monograph of similar cases; He described these subjects as “carriers of dyslexic disorders”. For these pioneers, this is a severe deficit of learning to read, occurring in intelligent children, and for which they suspect an organic neurological origin.
Orton, a neuropsychiatrist and neuropathologist in the United States, is responsible for taking dyslexia into account in medical history. Between 1920 and 1940, Orton examined nearly 3,000 dyslexics of all ages. He speaks first of “specific disorders of reading”: it appears to him that, apart from reading, visual perception is excellent in these subjects. He introduces a notion of “cerebral determinism”, due to the observation of particular errors (production in reversed letter reading) and a high frequency of patients with mixed or crossed laterality. Orton formulates for the first time the hypothesis of a disorder of the hemispherical lateralization. It also highlights the increased frequency of dyslexia in boys as well as its often familial character, thus paving the way for a probable genetic trail.
Orton had devoted a great deal of time to the development of methods of rehabilitation, and his theories had been favorably received in educational circles. The impetus given by Orton’s work continues in the United States. The Orton Dyslexia Society has, in particular, funded neuroanatomical research in Galaburda.
Definition of dyslexia:
In 1968, a definition of dyslexia was proposed by a panel of experts from the World Federation of Neurology: “reading disorder, occurring in spite of normal intelligence, absence of sensory or Neurological, adequate schooling, and adequate socio-cultural opportunities “. This disorder is opposed to the simple delay in reading: a longitudinal study carried out on the Isle of Wight, whose population is perfectly homogeneous, reveals the existence of a group of intelligent children whose reading delay is Minus two standard deviations from children of the same age. The incidence of this group is 4% among 10-year-olds.
In 1975, in the United States, a national panel of experts highlighted the possibility of multiple handicaps and a coincidence with an unfavorable socio-cultural environment, but these circumstances should not be considered as causal.
The American Classification of Mental Disorders (DSM) IV situates dyslexia in the “specific disorders of learning”. Under this heading, DSM IV includes reading disorders, computation disorders and writing disorders in subjects with normal IQ and at least two standard deviations between academic performance and IQ .
Developmental dyslexia is defined as a significant and persistent disturbance of learning to read in spite of normal intellectual efficiency, adapted teaching, satisfactory socio-cultural conditions and lack of primary (visual) visual sensory deficits Or auditory) or acquired acquired neurological lesions. The reading level, estimated through standardized tests, must be at least 18 months lower than the child’s actual age. This disorder is long-lasting because it interferes with the child throughout his or her schooling. Sequelae are still generally present in adulthood.
Many debates about the extrinsic or intrinsic character of dyslexia, or even its very existence, are still relevant. The discussion focuses on the bimodal or continuous nature of the distribution of the lexicon abilities of a population. The degree of severity of exclusion criteria (such as sensory disturbances or psychological problems, or even the normality of intellectual abilities) is also contested by some.
Prevalence. Links between dyslexia and illiteracy:
Twenty-five per cent of the population would have difficulty learning to read; But only a fraction could be considered dyslexic (about 5% of the population).
Some give even more severe figures: out of 124 subjects of average age equal to 21 years in difficulty of social and professional integration, 35% presented difficulties of deciphering. Of these 35%, nearly half were diagnosed with developmental dyslexia. One might therefore consider that there is a not insignificant contribution of dyslexia to the social problem of illiteracy.
Dyslexia is not responsible for all reading failures due to sensory problems, intellectual delay, psycho-affective problems, an unfavorable socio-cultural and pedagogical environment.
The so-called “semi-global” methods of learning to read are also questioned, at least as aggravating factors. A return to the syllabic method is currently advocated in several countries, including France.
Etiology. Pathogenesis:
It is currently recognized that dyslexia is a cognitive inability that frequently has a constitutional origin.
These children have an inability to develop certain cognitive processes necessary for reading activity, following the existence of neurodevelopmental anomalies. Depending on the causal chain of dyslexia, the quality of reading performance of these children would result from cognitive dysfunction secondary to a cerebral abnormality having a genetic origin. Dyslexia can therefore be characterized at three levels: behavioral (there is as yet no biological marker or imaging of developmental dyslexia), cognitive and neurofunctional.
Research in neurobiology: work on the brain of dyslexic
Initial work in the field of dyslexia was carried out by the American neurologist Geshwind (1926-1984) who took up the hypothesis of a disorder of the hemispherical lateralization proposed half a century earlier by Orton. He showed the existence of an abnormal functional lateralization in dyslexics, in particular by the studies carried out by means of the dichotic listening test.
The original work of Galaburda and Kemper (1979) revealed cerebral peculiarities in dyslexic subjects.
Postmortem studies revealed an abnormally polymicrogyric cortex in the areas of the left temporal planum (corresponding to the Wernicke language areas), as well as neuronal ectopies in layer 1 of the left cortex.
Morphological features concerning the absence of asymmetry of the temporal planum have been described by Galaburda et al.
At present, imaging research has taken over from research in neuropathology. Dyslexics were compared to different control groups (normal, hyperactive).
We have been able to put into perspective the anatomical characteristics and the functional characteristics of the brain of the dyslexics: only the dyslexics with important phonological disorders would have this morphological peculiarity that is the asymmetry of the temporal planum. The significance of these asymmetries remains obscure. Some of these abnormalities may be considered as a neurobiological marker of the maturation anomaly leading to the dyslexic disorder, although they do not represent the direct cause.
Microscopic abnormalities have been demonstrated in the subcortical stage, especially in the thalamic relay nuclei of the visual (lateral geniculate) and auditory (medial geniculus) nuclei. Some data highlight an asymmetry in the proportion of large cells in favor of the left side for the control subjects and on the right side for the dyslexics.
How to interpret the triad “dyslaterality, learning disabilities, immune disorders (in particular a high frequency of allergies)” found in these patients in the literature? For Geshwind, this association is not fortuitous; He hypothesized that the level of male hormones in fetal blood at certain periods of brain growth could cause abnormalities for the development of certain critical areas and cognitive functions, particularly those related to language. Geshwind’s hypothesis of a link between fetal testosterone levels and subsequent learning disability has never been demonstrated (cited by Habib).
The main dynamic imaging results showed differences in cerebral activation between normal and dyslexic adults. Some asynchronies between different brain areas could be noted in dyslexic subjects, which may lead to suspicion of functional dysconnection of the speech areas. Other studies have shown hypoactivation of the posterior regions and normal activation, or even overactivation, of the anterior regions during reading and / or phonological tasks. The hypoactivity of the temporal and posterior regions observed in dyslexics during phonological tasks on auditory input reinforces the hypothesis of an underlying phonological deficit.
Currently, brain functional neuroimaging techniques coupled with a psycholinguistic approach to language functions provide an excellent methodology for exploring the cerebral correlates of dyslexia and for testing the validity of physiopathological hypotheses. These techniques have made it possible in particular to carry out an international study on French, English and Italian dyslexic subjects.
Genetic factors:
The family incidence of dyslexia is indisputable. Within the same family, we can find several cases over several generations, with arguments in favor of an autosomal dominant transmission.
Genealogical surveys in families of affected individuals, as well as studies of twins, argue in favor of a hereditary component in dyslexia. When a subject is suffering from dyslexia, a similarly affected relative is found, in an average proportion of 35 to 40%. A strong male predominance is verified (four boys for a girl). In monozygotic twins, studies show a concordance of 70%, and only 43% in dizygotic twins; The comparison of true and false twins makes it possible to dissociate the respective contributions of environment and genes. Recent genetic studies have identified at least five chromosomal regions involved in the etiology of dyslexia.
Molecular biology research currently focuses on chromosome 6. It has been possible to demonstrate a mutation of the short arm of this chromosome affecting a gene that could be involved in neuronal migration during cerebral development. The mutation may have implications for the functioning of the brain areas involved in reading and writing.
Some competencies or cognitive dysfunctions were compared with data from molecular biology, but these results have been challenged.
Psycho-affective factors:
For a clear reading of the phenomena involved in dyslexia, we refer to the bio-psycho-social model.
This model proposes a three-dimensional reading of any pathological phenomenon comprising an objective dimension, a subjective dimension, an intersubjective dimension, these three dimensions being in perpetual interaction in the child.
The perceptivocognitive aspect of the disorder constitutes its objective dimension. This dysfunction affects the child’s psycho-emotional organization from an early age, that is to say, well before the age of primary school. The difficulties of learning to read in the preparatory course spoil the child’s enjoyment of going to school, learning, and seriously shaking his self-esteem. The subjective dimension is thus also reached.
The disappointment experienced by the parents of this child in the face of this failure, the renunciation of the idealized image of their child’s success, the narcissistic wound they experience, even if they have been faced with academic failure (Or sometimes, a contrario, if their schooling has been brilliant), all this constitutes the intersubjective dimension. This narcissistic wound is often taken up by the teacher himself.
The psychodynamic theoretical approach insists on taking into account the psychic organization of the child, in the pathological context that is his. The secondary benefits of the disorder are often present: the maintenance of immaturity and lack of autonomy; The persistence of a fusional relationship between mother and son, from which the father is often excluded, with hours spent every evening spent on homework. The associations between psychopathological manifestations and developmental dyslexia are numerous: the coexistence between dyslexia and emotional disorders reinforces the interaction between these two aspects and maintains the vicious circle of academic failure.
Some dyslexic patients may fall into the category of borderline pathologies (or “dysharmonies of evolution”), with a poorly structured personality, an important emotional dependence, an immaturity, and a difficulty to differentiate between reality and imagination.
Clinical experience could lead to the hypothesis, in a child already at risk of dyslexia, of a decompensation of a neuropsychological weakness during an affective shock that occurred in the final section of kindergarten or in the first year of primary school (That is, concomitant with the first learning of reading). At present, psycho-affective factors are accepted as aggravating factors in an underlying neuropsychological disorder.
The characteristics of the psychosocial environment are an important predictor of the evolution of disorders. Alterations in family functioning are frequent: disorders interfere in the child’s relational world.
It is difficult to describe a typology of the dyslexic child’s family. Nevertheless, it has often been described that fathers who are not engaged (or indifferent), even tyrannical, and mothers over-involved, with extremely complex interactions and strong stakes around homework and school.
Whatever the typology of the family, the evaluation of its functioning proves very useful to guide the follow-up and specify the therapeutic objectives. Thus, five types of families have been described (this typology is obviously not limited to families of dyslexics): the authors find “healthy, fragile, disorganized, rejecting, divided” families. The “healthy family” is one where the child’s difficulties do not destabilize the family. In the “fragile family”, communication is restricted within the family group, there is less interest in schooling. The “disorganized family” is experiencing multiple problems, making any therapeutic approach difficult. In the “rejecting family”, the child is made responsible for all his difficulties, is constantly blamed, which further diminishes his self-esteem. The increased risk of maltreatment (especially psychological maltreatment) should not be overlooked. Within the “divided family”, parents are separated, the problem of the child is an integral part of the conflicts of the parents and contributes to feeding them.
Cognitive explanatory theories of dyslexia:
Phonological theory:
Over the past 25 years, this theory has emerged as the classical theory of dyslexia. Learning disabilities of reading are often accompanied by a phonological deficit. Here, developmental dyslexia is the consequence of a specific phonological deficit. The majority of dyslexics would have a phonological cognitive deficit, the other disorders being part of a more general “sensorimotor syndrome” associated.
The role of “phonological awareness” has been amply demonstrated in the acquisition of reading, suggesting a reciprocal causal relationship between these two skills. By phonological consciousness we mean the consciousness that the child acquires that speech is made up of sounds. The child progressively acquires the ability to identify sounds, manipulate them within a word, perform a segmentation of words into syllables and sounds. The performance of preliminary readers or beginners on metaphorological tasks is predictive of the future level of reading. Metaphonic training in preschool children improves their reading skills. Moreover, the hypothesis of a phonological disorder in dyslexia has been confirmed by using metaphonological tasks requiring a voluntary manipulation of the phonemes that compose the words (tests of rhyme judgments, sound omissions, counts Phonemics, categorization of sounds, counterspelling, acronyms).
In particular, dyslexic children present difficulties in repetition, which are manifested during the repetition of words and especially of non-words.
Dyslexic children also have difficulty accessing the phonological form of words which translate into hesitations, lack of word or high latency in word denomination. These children also have deficit performance in lexical evocation tests and are slow in automatic rapid naming tests.
Difficulties are also common in short-term auditivoverbale memory tasks. This phonological deficit is observable in children even before learning to read, and is an excellent indicator of future difficulties in reading.
The clinical data also show that a large number of dyslexic children have difficulty learning oral language ranging from simple delay to developmental dysphasia.
On the basis of these observations, reading difficulties (notably non-words), phonemic awareness deficit and language difficulties of dyslexic children were interpreted as resulting from an underlying phonological deficit.
This phonological disorder is currently widely regarded in scientific and clinical circles as being largely responsible for developmental dyslexia.
For the advocates of phonological theory, this disorder is always present, although it may be associated with other types of cognitive, visual, motor, attentional or other deficits.
Among the techniques of auditory explorations which make it possible to demonstrate the disorders of auditory perception, one can cite mainly the tests of categorical perception and the evoked potentials late.
Magnocellular theory:
Disorders of the visual treatment were very early evoked as being able to be at the origin of the difficulties of acquisition of the written code in dyslexic children.
At present, magnocellular theory unifies the auditory, visual and motor hypotheses: a single neurological anomaly, concerning the magnocellules of all the sensory pathways, is at the origin of all the symptomatology, evoking a general sensorimotor syndrome.
Here, a lack of integration of fast temporal information would be at the origin of the reading difficulties of the dyslexic subjects. This shortfall in the integration of rapid information is considered to be a central amodal disorder capable of disrupting both auditory and visual information. This hypothesis makes it possible to explain the concomitance of the phonological and visual deficits observed in this population, and more particularly of phonological dyslexia.
Experimental work shows that the performance of dyslexic subjects differs from that of the control subjects on low-level visual processing tasks, with phenomena of abnormally long visual persistence, reduced sensitivity to low spatial frequency and high temporal frequency contrasts , Disorders of movement discrimination.
A decrease in temporal resolution due to the magnocellular system could lead to a superposition of the extracted information during each successive ocular fixation. This disorder of the magnocellular system is present in 75% of dyslexic children.
Visuoattentional Theory:
For some authors, visuoattentional mechanisms would also be fundamental in reading activity. It has been shown that the visuoattentional treatment capacities of normolactoric children are correlated with their level of reading: in reading, children with the lowest performance in a target-search test among distractors read significantly less quickly and commit A higher number of visual errors than children who performed well in this task.
Thus, the hypothesis of a deficit of selective attention was the source of this difference between good and bad reader.
A deficit in the distribution of attentional focus on the whole of a sequence of letters (“reduction of the attentional window”) has been demonstrated in a dyslexic child. The partial distribution of the attentional focus on the left part of the word would allow the patient to read using the assembly path by successive displacement of the attentional focus, the alteration of the overall distribution of attention making it impossible to read by the ” Addressing.
Dyslexic children would have superior peripheral visual processing and an inferiority of central visual treatment, as opposed to control subjects with a maximal letter recognition score in a central position and a progressive decrease in performance as a function of the degree of eccentricity. This superiority of the parafoval treatment could suggest a disorder of the inhibition of peripheral information. Instead of focusing their attention in the foveal region by inhibiting peripheral information, dyslexic children appear to be particularly sensitive to surrounding stimuli, which may interfere with central vision therapy.
The described visual difficulties would only concern certain subtypes of developmental dyslexia called “surface dyslexia”.
A phonological deficit would be at the origin of so-called “phonological” dyslexia (the most frequent form); A visuoattentional deficit is more likely to be the cause of “surface” dyslexia. The presence of a double deficit (phonological and visuoattentive) in certain subjects could then correspond to forms of dyslexia called “mixed”. The association of these two deficits should be observed only in a more limited number of dyslexic children, these cases being the most difficult to treat.
Cerebellar Theory:
In addition to its long-established role (a role that could be implicated in coordination disorder), the cerebellum has recently been implicated in general cognitive functions: in particular those related to temporal organization, not only But also more complex activities, including various non-motor learning, and the automation of certain procedures. Cerebellar theory in dyslexia calls for the primordial role of the articulation of speech in the learning of language. There would be a subtle deficit in articulatory skills that would cause both an articulatory loop (altering phonological memory in the short term) and a phonological awareness disorder, two integrity-critical processes reading.
Currently, in clinical practice, this theory has not yet led to specific tests.
Typology of dyslexia:
Current theoretical framework: the so-called “dual track model”
This model is currently the reference for the various clinical classifications of dyslexia. It succeeds the model of the “logogen” of Frith. The limitations of these models are that they were originally conceived as part of adult neuropsychology and do not take developmental factors into account.
The “dual track” model distinguishes:
• the direct reading channel (also referred to as the addressing channel, or lexical channel); It is a mode of reading by global recognition of the word; This way allows the rapid reading of words already known, regular or irregular (“woman”, “chorale”), already stored in the internal lexicon;
• the indirect reading path (also called the assembly path, or phonological path); It allows the reading of regular words, new words or non-words, by syllabic deciphering; This way makes it possible to decipher the unknown words by the application of the rules of correspondence graphophone.
A new word, encountered and deciphered several times by the phonological way, will become a known word, which can be added to the lexical stock and then read in global recognition. A competent reader is expected to efficiently use the two playback channels, simultaneously or alternately, depending on the nature of the playback task.
Dyslexia (“phonological”, “surface” or mixed dyslexia) is the clinical form of both (or both) reading pathways.
The analysis of the error profiles obtained during the various evaluations makes it possible to identify well-differentiated subtypes of dyslexia. Three main types of developmental dyslexia have been described in the literature:
• phonological dyslexia;
• “surface” dyslexia (also known as visual or dysideidetic dyslexia);
• Mixed dyslexia (combination of the two previous forms).
Phonological dyslexia and surface dyslexia are clinically differentiated by contrasting error profiles and are most commonly found in children with learning difficulties in reading.
Phonological dyslexia:
Referring to the “dual-track” model, phonological dyslexia is interpreted as a selective deficit of reading and writing through the assembly pathway. This way of reading, thanks to phonological mediation and the application of graphophonemic correspondences, allows the reading of new words, pseudo-words and regular words.
Phonological dyslexia is characterized by a reading of known (regular and irregular) words and a particular difficulty in reading non-words (meaningless words). The errors produced in the reading of non-words correspond either to lexicalizations or to phonemic paralexies. A “lexicalization” error consists in producing a word, visually or phonologically close, instead of a non-word (example, “chein” read “dog”, “viala” read “voilà”). The phonemic paralexies consist in producing another non-word obtained either by substitution (“caldon” or “galdon”) or by omission (“courlone” lu “coulone”) or by displacement (“panilotur” or “palinotur” Or by addition (“miscla” lu “miscala”) of one or more phonemes.
In reading words, we find visual paralexies which consist in reading a word in place of another on the basis of a visual similarity (“lame” read “tear”), as well as morphological paralexies (“spectator” The “show”).
In writing under dictation, we find difficulties similar to those observed in reading. This is called phonological dysorthography. The errors committed do not respect the oral form of the word (examples: globule-clodule, vine-ving, club-goutin). Spelling of familiar words is preserved, but difficulties are encountered during the dictation of uncommon long words. The dictation of non-words is very deficient, the errors committed are often nonphonologically plausible errors. In this case, the rules of phoneme-grapheme correspondence are not respected and the word transcribed is not pronounced as the dictated word.
Surface dyslexia (visual or dysideidetic):
According to the “dual-track” reading model, surface dyslexia corresponds to a selective deficit of reading and writing by the addressing pathway. Surface dyslexia is characterized by severe difficulties in reading irregular words. On the other hand, the reading of regular words and nonmots is relatively preserved. The errors found in reading irregular words are mainly regularizations (“woman” read “feme”, “sept” lu “sepète”). Visual paralexies and, more rarely, phonemic paralexia are also present.
Regularization errors reflect the systematic application of the rules of graphophonemic correspondence in reading words: the subject here uses a phonetic reading.
Understanding of written language can be disrupted. Indeed, surface dyslexics sometimes tend to rely on the phonological form produced to extract the meaning of the word.
Thus, confusions of meaning are observed when reading non homograph homophone words. For example, the word “rum” is regularized [rym]. The meaning assigned is then that of the word “cold”.
Surface dyslexia is accompanied by so-called “surface dysorthography”. Here, the errors produced concern the writing of irregular words, the sequence produced respecting the phonological form of the word but not its spelling (“woman” writes “fame”, “monsieur” writes “meusie” ; “Exam” means “éqsamin”). Unlike phonological dyslexia, errors are therefore most often phonologically plausible. Having no visuoorthographic trace of words, these children invent the spelling of irregular words each time they write them, and can write successively the same word in different ways; Sometimes in the same text, or even in the same sentence. This phenomenon is extremely disconcerting for the entourage.
Mixed dyslexia:
When the two “reading pathways” are affected, we speak of mixed dyslexia (about 20% of dyslexia). These cases are the most severe and the most difficult to treat because the child associates the problems of the two previous forms. It can not rely on either of the two reading channels to develop compensation strategies. In the most severe cases, the picture may be confined to deep dyslexia or even alexia.
In reading, errors are massive on all types of words, especially on irregular words and non-words.
In dictation, the difficulties are similar. We talk about mixed dysorthography. The spelling of irregular words each time they write them and can therefore successively write the same word in different ways; Sometimes in the same text, or even in the same sentence. This phenomenon is extremely disconcerting for the entourage.
Mixed dyslexia:
When the two “reading pathways” are affected, we speak of mixed dyslexia (about 20% of dyslexia). These cases are the most severe and the most difficult to treat because the child associates the problems of the two previous forms. It can not rely on either of the two reading channels to develop compensation strategies. In the most severe cases, the picture may be confined to deep dyslexia or even alexia.
In reading, errors are massive on all types of words, especially on irregular words and non-words.
In dictation, the difficulties are similar. We talk about mixed dysorthography. The spelling is very altered on all types of words.
Dyslexia secondary to a speech-specific disorder:
A number of children who have been referred for a severe reading delay (for example, from the age of 9 years) have, in a significant number of cases, presented a severe speech-specific disorder Developmental dysphasia, of which dyslexia is one of the consequences.
Oral language disorder is not always compensated for when the child reaches the middle of the primary cycle. The child then presents a hypospontaneity of discourse, syntactic difficulties, a lack of the word, semantic paraphasias.
In these subjects, the speech-language assessment and the psychometric tests correspond to the accepted criteria for a diagnosis of dyslexia: at least 18 months of delay in reading in a subject with at least one normal performance IQ. A closer examination shows that this child has a significant disorder of oral language that is partially compensated but is not taken into account at all, with speech therapy focusing on written language.
In some cases, if there are significant oral comprehension disorders, a diagnosis of mental impairment may be mistaken.
Consequently, before any child with reading difficulties, it is necessary not to be content with an evaluation of the written language, but also to ask for a detailed oral language assessment, in order to avoid disregarding dysphasia.
Limits of typology:
The “pure” cases described in the literature are quite rare. Mixed forms, environmental factors and / or associated disorders often make “pure” forms infrequent.
Another criticism of this typology is that it is at a purely descriptive and behavioral level and does not give any information about the cognitive level of the disorder. Moreover, the dual-track model is derived from adult neuropsychology and gives no indication of the developmental trajectory.
It is therefore necessary to grasp it in this perspective, bearing in mind that the two reading paths (by addressing and by assembly) interact. As a result of this interaction, a mixed dyslexia may be sometimes hastily overcome, whereas in fact one of the two reading paths may be simply under-stimulated. These elements are fundamental in terms of rehabilitation and make it possible to work really the most affected aspects.
Research on the classification of different types of dyslexia has been conducted primarily through case studies; The frequency of subtypes of developmental dyslexia remains difficult to estimate precisely, especially if one relies solely on the quantitative performances in irregular word reading and non-words. Moreover, this prevalence may vary from one country to another due to the characteristics of the language.
It has been shown that, of 53 dyslexic children tested, 72% have a profile similar to that of phonological dyslexia; In this study, the proportion of surface dyslexic children was 19%.
Although the existence of subtypes of developmental dyslexia is currently widely accepted, the question of the nature of the underlying cognitive dysfunction (s) at the origin of various clinical forms is still under discussion.
The determination of the type of dyslexia must be based on a quantitative and qualitative analysis of the efficient and deficient reading mechanisms. The age of the child, the pedagogical and rehabilitative methods used and the antecedents must also be taken into account. The precise diagnosis, often delicate, requires a pluridisciplinarity and experience. It is important that it be established, as it has far reaching consequences for the type of rehabilitation to be undertaken.
Diagnostic and clinical approach:
Particularities of the clinical interview:
A history of reading difficulties, or severe disorders of pre-existing oral language, as well as possible bilingualism, should be specified.
It is important to inquire about the associated disorders: behavioral disorders; Attention deficit disorder; Difficulties in calculation … A possible psycho-affective deficiency or a lack of stimulation are to be sought.
Similarly, it is useful to specify the presence of a family history of delayed speech and language, or dyslexia-dysorthography.
Additional essential medical advice:
Ear-nose-throat and audiometric examination eliminates transmission deafness and possible cochlear involvement.
The ophthalmological examination makes it possible to make a visual correction often necessary.
If dyslexia is accompanied by severe language delay, or even a regression of oral language, a neuropediatric examination may be necessary.
Assessment of Language and Cognitive Skills:
The assessment of dyslexia may in itself have an important therapeutic value if, after consultation between the various participants, the necessary time is taken to restore the content of the various assessments to the child and his / her family. Naming the disorder has an important symbolic value; The confirmation of normal or even superior intellectual capacities revalorizes the subject in his or her own eyes and those of his or her entourage and can help to overcome certain depressive states.
Speech assessment:
Theoretically, this approach is carried out with reference to cognitive and neurolinguistic models, which are useful for analyzing errors and specifying the type of dyslexia.
The objectives of language assessment in the context of dyslexia are mainly to determine the nature of this dyslexia while evaluating, as far as possible, the underlying deficiencies, their consequences, but also potentialities such as emerging compensation strategies or Already put in place by the patient.
The assessment must be precise and reproducible, since it serves as a starting point for all re-educative follow-up, which must be regularly evaluated. It is therefore essential to have quantified data, and for this to have recourse to calibrated and standardized tests. However, even if certain tests prove to be unavoidable for this pathology, there can be no standard assessment. Indeed, the tests selected at the time of the check-up depend on both the age of the patient and his / her assumed level of education. This implies that a speech-language assessment in the context of dyslexia must include a certain number of key tests, but that for each patient an adaptation of the initial frame is necessary.
In any case, an anamnesis precedes this assessment. We analyze the development of oral and written language, the learning of reading (as well as the reading methods used), the progress of schooling (class break, repetition, adaptation to rules, relationship with teachers, Comrades), extracurricular activities, assessments and care already taken (speech, psychological and / or child psychiatric, psychomotor, orthoptic). The data collected during this interview with the family, as when observing the patient’s behavior during the assessment, are rich in education.
Oral language:
A delay or sequelae of an oral language disorder has implications for the mastery of written language. Indeed, as the maturation of cognitive abilities and linguistic consciousness progresses, a child becomes aware that speech is made up of sounds (see above). This is called “phonological awareness”, which allows to segment a word into sounds, to identify and count them, to analyze their sequence within a word. However, it has been shown that children with limited phonological awareness often have difficulty learning to read; Conversely, those who have acquired a sufficiently developed phonological awareness generally become good readers. The phonological awareness is a good predictor of reading and becomes more and more effective as the learning of reading.
Classically, the capacities of comprehension and then of expression are evaluated. First of all, it must be ensured that the auditory perceptive capacities of the patient are satisfactory.
Assessment of listening comprehension. The ability to discriminate phonetically, to understand the vocabulary (or lexical stock) is tested by a word-naming task, the syntaxicosemantic processing skills (which cover the child’s ability to interpret a message according to the order words).
Evaluation of oral expression. Spontaneous oral expression is compared with the data collected during the various tests.
First, good oral praxis is a prerequisite for correct oral expression.
The articulation is then explored by proposing to the child to repeat uni- or plurisyllabic words whose construction is different according to the position of the consonant. The analysis of the articulatory productions of the child thus makes it possible to evaluate the establishment of the phonemic system from the point of view of production.
Audiophonic encoding and decoding capabilities are evaluated through repetition of difficult words such as “show”, “playful”.
The capacities of access to the internal lexicon are explored thanks to a denomination of images and compared to the capacities obtained in lexical understanding.
Verbal fluency tests consist of giving a maximum number of words in a given time, respecting a semantic constraint (for example, giving trades) or a phonemic constraint (for example, giving words starting with the letter “f”), . They allow to test the speed of access to the lexicon.
Reading tests:
In a first step, the reading is evaluated aloud.
The evaluation of the speed of decryption (ie the optimum speed that allows to read without error) is an indispensable stage of the balance in the context of a dyslexia. The current reference test is the Alouette ® . This test can be used to calculate a patient’s “reading age” in years and months. The comparison of this “reading age” with the patient’s chronological age makes it possible to determine whether or not there is a “lexical delay” and to measure it precisely. To affirm dyslexia, this lexical delay must be at least 18 months. Different degrees of severity of dyslexia are defined: mild (delay of less than 2 years), mean (between 2 and 4 years of delay), severe (more than 4 years delay). It is important to note that two years of reading age lags do not have the same significance and severity at age 9 as at age 15, as part of normal schooling.
Reading out loud also makes it possible to evaluate prosody and respect for punctuation. The orized reading of a young dyslexic is classically hesitant, slow, jerky, monocord, syllabic with backtracking. These difficulties of decryption lead to fatigability and are also source of errors in understanding.
The evaluation of the reading strategies is done with reference to the dual channel reading model: this evaluation describes the mechanisms involved when reading a word by an ordinary reader using alternately the two reading channels (by addressing or By assembly) according to the nature of the word presented (see above). It is thus possible to define the type of dyslexia suffered by the patient and to propose to him an adapted management of his difficulties.
This evaluation is carried out by means of tasks of reading aloud lists of non-words (also called pseudo-words or logatoms), lists of regular and irregular words, more or less long and more or less complex that are proposed to him .
The comparison of reading times and accuracy scores for these different lists, as well as the analysis of the types of errors committed, makes it possible to determine which reading channel is deficient and which is preferentially used by the patient.
Reading comprehension is analyzed by means of a silent reading of texts, followed by questions. It is common to observe dissociations between reading and silent reading skills, as silent reading results are often better. However, it is not uncommon for a dyslexic, even with a good level of reading comprehension, to be penalized by his slowness.
Written expression:
The written expression is analyzed (dictation, spontaneous expression), with a view to seeking:
• dysorthography, or disorder of acquisition and mastery of spelling in the broad sense, very often associated with dyslexia; These difficulties can be found at different levels, that of the phoneme-grapheme conversion (aptitude which allows the child to transcribe sounds into letters, but which in the case of perceptual deficiency causes him to commit errors such as: Not too much pear before driving “), or that of the lexical skills (in case of difficulties, there may be faults of homophones) or grammatical (these are faults of agreement);
• a dysgraphy: it involves an attack on the graphic gesture, often with clumsiness, contraction, slowness; It is very often associated with dyslexia-dysorthography.
Exploring underlying cognitive processes:
Speech-language assessment must ensure that the dyslexic patient has the cognitive skills necessary for learning and mastering reading.
Phonological awareness is explored through specific tests of syllable and phonemic manipulation.
Memory systems include:
• short-term hearing memory, which is evaluated by repeating a few digits to the child (empan mnemic place);
• working memory, which is evaluated by repeating these numbers in reverse (backward);
• long-term verbal memory, which can be quickly assessed by repeating phrases of increasing length or by the immediate, then deferred recall of a story; Visual memory is evaluated by means of reproduction of increasingly long series of signs.
Visuoattentional processes are essential skills for the identification and spatial understanding of forms, the memorization of their succession, and so on. Different types of dam tests (figures, letters) are used to evaluate them.
Visual visuoperceptive skills are assessed on the one hand by the capacities of visual discrimination, for example by recognizing drawings of objects intertwined on the same image and on the other hand by visuospatial reasoning, with a task of completion of forms by example.
Orthoptic and neurovisual assessment:
It is a useful complement to speech-language assessment in cases where there is doubt about the efficiency of visual scanning, especially in “surface” dyslexia. In the context of dyslexia, the orthoptic assessment requested is wider than a usual assessment of the sensory and motor function of the eyes in the context of a suspicion of strabismus or a lack of convergence, for example.
Indeed, in the context of dyslexia, a specific neurovisual exploration of the strategies of the gaze is useful. We then explore visual pursuits, eye drops, and research strategies.
This assessment can lead to a specific rehabilitation in order to improve not only the speed of reading, but also spatial and graphic construction. The improvement of visual strategies often has a positive impact on the attentional qualities of the dyslexic subject.
Psychometric and neuropsychological assessment:
Weschler scales are used to assess the intellectual level of the child, which is an element of diagnosis. This level should be normal in dyslexia (> 85). This examination is necessary to identify an associated intellectual precocity or, on the contrary, a limiting level, even an intellectual deficiency.
Some subtests of the WISC III (arithmetic, code, memory of numbers) make it possible to identify possible attention problems. At WISC IV, these disorders can also be detected by the work memory index and the processing speed index.
The results dissociation analysis at the WISC III verbal and performance scales may reveal dysphasia (IQ performance greater than verbal IQ) or dyspraxia (verbal IQ above IQ performance).
This examination allows, through its subtests, to develop a neuropsychological profile of the child. This test does not evaluate the reading capabilities. The confirmation of a good intellectual level contributes greatly to restoring confidence in the child.
Complementary neuropsychological tests are useful in seeking alterations in the higher mental functions often associated with dyslexia, particularly in the areas of memory, attention, visual skills, executive functions, praxis.
The neuropsychological assessment also makes it possible to deepen the study of cognitive functioning, in search of its cognitive origin, and also to specify the type of dyslexia.
The data collected, compared to the results of the other investigations, are very useful in guiding the management of the patient.
Associated pathologies. Dyslexia and intellectual precocity:
Several psychopathological syndromes are frequently found in association with learning disabilities of reading. These are mainly depressive states, anxiety and phobic disorders, behavioral disorders and attention deficit hyperactivity disorder (ADHD).
Depressive Syndromes and Anxiety Disorders:
Some of the points of appeal of depressive syndrome may be sleep disorders or diet, sadness, disinterest and academic refusal. These are usually depressive disorders. The depressive state further reduces learning abilities. The low self-esteem at the origin of this depressive state is often related to the representation that the entourage makes of the child. At the extreme, attempts at suicide in adolescents may be part of the clinical picture. Often, the psychological suffering caused by learning disabilities tends to be underestimated and not treated for its own sake. Depression and loss of self-esteem can also lead to behavioral and behavioral disorders, especially in adolescence. They sometimes result in exclusions from the regular school environment and unjustified placements in specialized institutions, the consequences of which can be disastrous.
The manifestations of anxiety are accompanied by guilt and self-reproach; Sometimes one arrives at the stage of refusal or school phobia. In our practice, several cases of dropping out of school were observed.
Attention Deficit Disorders with Hyperactivity:
This disorder typically consists of the association of three symptoms: motor instability; Impulsivity; Attentional disorders. There are different clinical forms where the picture can be more or less complete. Attention disorders are very common in dyslexia, regardless of the type. This attentional disorder is then found in all cognitive activities, and not only in reading.
About 25% of dyslexics would have ADHD. The respective proportions of attentional disorders and hyperactivity are variable.
If ADHD is suspected, an appropriate neuropsychological assessment should be proposed.
Association dyslexia-intellectual precocity:
Early childhood is considered to be intellectually superior to the average expected for age (IQ> 130). This concerns 2.5% of the population. Precociousness often creates a significant gap between children’s cognitive abilities.
In dyslexics, reading delay further aggravates this displacement. In terms of care, we are often confronted with critical situations, a lack of understanding between families and teachers.
High intellectual capacities allow some dyslexic children to compensate for their difficulties without being really helped by personal strategies and thus to pass through the screening and diagnosis of dyslexia to a relatively advanced age. Decompensations then occur at the college level, in the 5th or 4th grade, with a collapse in academic performance and severe depressive disorders. These adolescents are often the subject of a request for urgent consultation in child psychiatry following a drop-out, a dismissal from school, severe behavioral problems, runaways.
Therapeutic Interventions:
In recent years, a large number of “dyslexia rehabilitation methods” have been disseminated and placed on the market. These methods are generally a reflection of the theories of dyslexia to which their authors adhere. At present, it is important to stress that no method has been scientifically validated.
Conventional therapeutic interventions should be based on the most accurate assessment of each patient’s case. They have everything to gain from being multidisciplinary. The child care program should be re-evaluated each year. At present, the centerpiece of the care system is speech therapy, often combined with other types of interventions.
Orthophonic rehabilitation:
General principles:
The rehabilitation of a dyslexia, whatever its type, is based on the previous assessment, which makes it possible to determine precisely which way of reading to work first, as well as the underlying skills to train (visual, auditory or memory) .
The frequency of sessions is difficult to determine, which must take into account the severity of dyslexia and associated disorders: disorders of oral speech (even dysphasia), dysorthography, but also of the level of education and the pressure of school, The existence of other simultaneous care (pedopsychiatric, psychological, psychomotor, orthoptic). Ideally, early and intensive initial management, at two or three weekly sessions, is recommended. It is thus possible to create real automatisms and restore confidence to the patient as to his ability to master written language. During the contract established at the end of the balance sheet, it can be agreed that the sessions will be spaced as soon as the objectives are reached, so that they can be stopped during therapeutic windows.
Objectives:
The objective is to enable the patient to acquire a mastery of the written language, which is essential for all subsequent learning.
This mastery consists in rendering on the one hand the functional reading and on the other hand the fluid transcription. A functional reading is an automated reading which allows an efficient, fast and minimal effort. A fluid transcription consists of writing without fear of committing errors of transcoding phony-graphy, homophony, use or grammatical error, with a good quality graphics.
Means:
The rehabilitation plan is drawn up according to the conclusions of the assessment and with reference to the theoretical model “dual track”.
Schematically, two main axes of management are identified: working the phonological path and / or working the lexical path. In the end, the normoliter must be able to use both read channels efficiently by switching from one to the other according to the needs of the current reading task.
The aim of restoration of the phonological pathway is to obtain an effective phoneme-grapheme conversion. To do this, it is useful to train phonological awareness by manipulating syllables and then phonemes (deletion, addition, segmentation, fusion, etc.), and on the other hand to favor the grapheme segmentation by Offering exercises such as welded words, hidden words, which require reading assumptions.
The restoration of the lexical path requires the increase of the orthographic stock or internal lexicon. For this stock to be constituted effectively, the visual image of the word must be associated with its meaning. Thus, it is useful to have a word read, to write it under dictation, to spell it up and down, to use it when creating spontaneous phrases, or in drills with holes . Reading words that are visually close, such as fast reading of words (“flash reading”), is also a very good training.
In parallel, rehabilitation of dysorthography should be considered if it is necessary. As before, the phonological and lexical aspects (ie the phonographic and semiotic functions of spelling) must be addressed simultaneously. Efforts should be made to make the most of the deficit in phonetic-grapheme transcription, while reinforcing the spelling of use. Freed from this double interrogation, the patient can then reflect on the application of grammatical spelling rules. Moreover, for this aspect of written language to be completely mastered and functional, it is fundamental to make ideas work and writing work work. Accompanying the patient on this side of the written language is all the more important because there is very often a great apprehension, coupled with a feeling of inferiority that must be fought.
Short-term memory and working memory must often be reinforced in dyslexics. Simple means can be used (games of Kim, memory, phrases with drawers, reproductions of visual sequences with tokens, reproductions of rhythmic sequences). This training can also be done using computer exercises.
The visual attention must also benefit from a specific training (exercises of barrage, investigation of the seven errors, of the forms-based discriminations). Auditive attention is exercised through sound lotto tasks, rhythms, discrimination and sound identification.
Progress must be encouraged by parents and supported by the teacher, who must be informed of the conditions of rehabilitation. Practical advice (reading with a cache, scoring, overtime) can dramatically simplify the dyslexic patient’s school life and make him / her aware that his or her efforts have paid off.
On the other hand, if it can be useful for a dyslexic to read aloud at home, it is often unbearable for him to do the same at school in front of his peers.
There is a difficulty in obtaining a generalization of the achievements made in the meeting as well as their automation.
In addition, as with other therapies, evaluative studies of the effectiveness of speech rehabilitation are severely lacking. However, these rehabilitations are at the present time the centerpiece of the care system in dyslexia.
Orthoptic Rehabilitation:
In some cases, it can be a significant supplement to care (see above).
Psychotherapeutic interventions:
They aim at a global blossoming of the subject rather than a treatment at all costs of the dyslexic disorder in itself.
Parents’ guidance and guidance, which is often indispensable, is sometimes sufficient. They are of course different depending on the functioning of the family.
The individual therapeutic follow-up aims in particular to renarcise and to render the child guilty. He must learn to better manage his frustrations. He needs help in finding compensation. It also needs to regain self-confidence, in a place from which the school is absent. In our experience, various psychological care can be offered:
• individual psychotherapy is essential when oedipal conflicts are at the forefront; It may be interesting to mediate, especially in children with severe language disorders, in depressed or inhibited children, or in cases of additional family conflicts;
• group care is of particular interest in children with behavioral disorders, in search of limits, or in the case of children who are very inhibited.
Psychological care is sometimes refused by parents, on the grounds that multi-weekly speech therapy is already very cumbersome. It is important not to overburden the child, but to see what is a priority at some point. At other times, on the contrary, in times of discouragement or crisis, it is the parents who are the claimants.
The period of adolescence presents some peculiarities: improvements in psychopathology are often found. The college is better suited to dyslexics than the primary school; The pupil is no longer under the all-powerful control of a single person (the teacher) or stuck between the teacher-parent binomial. The fact that there are several teachers paradoxically makes the pupil more independent; It will be able to allow itself a small autonomy, whereas it was until then “under close supervision” and that the weight of the interpersonal relations parent / teacher was often too pregnant. In addition to this pairing, the speech therapist, who has often taken charge of him for several years. It is often also the moment when the adolescent asks to interrupt speech therapy and where there is a real desire for emancipation. Conversely, severe decompensations are often observed if the disorder is not sufficiently taken into account by the school and if the family support is little present. One can lead to a serious school phobia, even cases of dropping out.
Caregivers in child psychiatry should keep in mind that dyslexia is a very frequent condition in the clientele of psychiatric centers, but that they are often undetected or undervalued, as the main reason for consultation is usually Not dyslexia, but one of the associated psychopathological tables (anxiety disorders, depressive state, behavioral disorders, school phobia, sleep disorders).
Current social and legislative framework for the management of specific disorders of oral and written language:
Under pressure from parents’ associations and certain professional groups, a ministerial action plan was launched, and a joint report by the General Inspectorate of Social Affairs / General Inspectorate of Education (IGAS / IGEN) Achieved. All these documents concern not only the problems of the written language, but also the disorders of the oral language which very often preexist.
Departmental Action Plan (2001)
It is a joint action of the Ministries of Health and National Education, to contribute “to better prevention of language disorders of whatever origin, specific disorders, Better and safer diagnosis, better management of the 4 to 5% of children concerned (1% with severe disorders) “. This plan represents both an element of the national integration policy and a priority for public health. It proposes several priority axes, among which:
• better prevention in kindergarten: the aim here is to better identify the subjects at risk (role of the maternal and child health services [PMI], school medicine and psychology); The goal is to prevent the onset of language disorders written by early intensive care of oral language disorders; Compulsory medical check-ups are carried out at 3-4 years and 5-6 years before entry into the preparatory course (first year of primary school);
• identification of affected students and better management; In most cases, mainstreaming is retained; For severe cases (less than 1% of pupils), a specialized class may be recommended, whether it is in the ordinary environment with the help of the health services or in specialized institutions; The creation or expansion of the number of primary school integration classes (CLIS) and of the Integrated Pedagogical Units (UPI) in secondary or high schools, specialized classes for children with severe language disorders, is also planned .
Within the framework of this plan is the creation of centers of reference within the university hospitals (CHU), whose mission is “to develop precise diagnoses, propose modes of care and consider Studies or research on the evaluation of such care “.
Report of the General Inspectorate of Social Affairs / General Inspectorate of Education (2002):
This report analyzes the whole system and takes into account all the professionals involved, whether they belong to health or to national education. The difficulties of integration in the ordinary environment, articulated with an out-of-school medical follow-up, are pointed out. As regards the health and medico-social system, the low number of specialists trained (especially neuropsychologists) is underlined. Liberal speech therapists take care of these children in the majority of cases, and are sometimes insufficiently trained. The problem of cumbersome cases and also of patients residing in rural areas arises, as well as the problem of referral errors (erroneous orientations towards medico-educational institutes). School medicine has made great efforts in training and testing. Infant and juvenile psychiatric services and medical and psychiatric centers are not the privileged interlocutors for the time being, due to their saturation with other pathologies and also the lack of trained personnel.
Hospital teams seem to be weakly involved, apart from a few CHU teams.
The centers of reference, with their diagnostic, networking, research and teaching functions, are still too few. They should integrate into a city network / medical / social institutions / school / hospital. The lack of multidisciplinary teams formed is still relevant.
The IGAS / IGEN mission proposes a survey of the prevalence of complex language disorders in the general population, as well as an inadequacy survey aimed at children suffering from complex language disorders who are not in the appropriate pathways. It is proposed a departmental structure that should allow all children to find a solution closer to their home.
Outlook:
Becoming Dyslexics:
In long-term follow-up, the persistence of symptoms in adulthood is often noted. Among the factors of good prognosis, one can especially note a high IQ, the family support, the good participation of the school environment. The severity of dyslexia, its mixed character, the importance of the associated disorders, the low family or educational support, are poor prognoses. The early diagnosis and the rapid introduction of appropriate management significantly improve the evolution.
In our experience, dyslexic adults sometimes reconcile their problem (often when it is necessary to take a professional step) and undertake a care approach.
Prevention:
Screening and treatment of speech and language delays in nursery school children contribute significantly to decreasing the frequency and severity of dyslexia-dysorthography. An intensive training of the phonological awareness in large section of kindergarten is an indispensable prerequisite for an efficient learning of the reading.
Current Issues:
The so-called “global” or “semi-global” learning methods of reading that have existed for decades and the problems they generate have contributed significantly to the problem of dyslexia, especially when these methods apply to Children already at risk of dyslexia (that is, carriers of speech and language delays, even treated).
The new official measures have had some questionable effects: indeed, in certain academies, National Education tends to leave the issue of language disorders in the hands of the health sector, ie reference centers and To liberal speech therapists, rather than strengthening the workforce of medicine and school psychology. However, an important part of the assessment (psychometric tests, level of reading) could well be carried out in schools, as is the case in several European countries, in particular in Great Britain. In this country, official diagnosis is the responsibility of the school psychologist, based on standardized test batteries (intellectual level tests or language-reading-phonology tests). Teachers or parents are the addressers. The dyslexic child then benefits either from support or from specialized schooling, depending on the degree of severity and the structures available.
The child also benefits from personalized adjustments to all exams: either extra time, a separate examination with a person reading the statement, or using the computer and the spell checker.
Referral center consultations should be reserved for complex and severe cases, but should not be used as a screening site, orientation platform or compulsory crossing point to obtain a third-time examination.
In these specialized consultations, it is not uncommon to see students who are diagnosed late (sometimes at the end of primary school) and who are three years behind the age of reading or more. They are therefore primary school-leaving pupils who hardly know (in some cases, not at all) read and who have nevertheless passed into the upper classes.
It is regrettable that the dyslexic child does not benefit more often from an adaptation of learning to read (eg use of gestures), or individual or small group support. Similarly, there are very few specialized classes. Parents’ associations, which have played an important role in the measures taken by the public authorities in recent years, are often in favor of the creation of this kind of specialized classes, as the global aspect of institutional care concerns parents who Are often in difficulty to ensure multi-weekly accompanying care. This creation of specialized structures is not without risk: on the one hand the marginalization of patients and on the other hand a tendency of the teaching body in the “ordinary” class to disengage from the children requiring specific pedagogy. Family associations are also concerned about secondary schooling, coaching and vocational training.