What is dyslexia?

Definition

Dyslexia is a common (5-10% of school age children) specific learning disorder that is characterized by difficulty recognizing words accurately and quickly when reading as well as when writing from dictation. This disorder leads to difficulties in reading comprehension and a lack of learning material and subsequently to a limitation of vocabulary and available knowledge. Effective correction of dyslexia is determined by early identification and comprehensive treatment.

Types of dyslexia

Dyslexia appears in early childhood and, if not corrected, can be accompanied by a deterioration in mental development. Dyslexia in adults is the result of damage to the cerebral cortex.
There are several types of dyslexia depending on whether it is at the level of the analyser, the auditory, the visual or the motor speech structures that are affected.

A child with phonemic dyslexia cannot distinguish between phonemes (sounds) that are similar in their hearing and articulation (g-k, z-s, z-s-h). Therefore, during reading, such children randomly substitute phonemes that are close in sound and pronunciation. Phonemic dyslexia is also a variant of phonemic dyslexia, where children either miss or insert extra letters when writing words. Sometimes they have difficulty putting two syllables together, which is referred to as "letter-by-letter" reading.

Semantic dyslexia, or "mechanical" reading - with this disorder, the child reads words correctly but does not understand their meaning. An indicator of semantic dyslexia is the inability to form words and phrases from a variety of syllables. In other cases, the cause is an intellectual retardation of the child - he or she cannot make grammatical connections between words in a sentence.

Grammatical dyslexia is the most common type of disorder. The disorder is manifested by a poor vocabulary and underdevelopment of speech. The characteristic feature of such dyslexia is improper coordination of cases and replacement of case endings.

There is also optical dyslexia, in which the child cannot recognize graphic images (letters) and therefore cannot learn to read.

Tactile dyslexia is characterized by impaired spatial awareness. Because letters differ in the number and spatial arrangement of dots, it makes it difficult to recognize them. Tactile dyslexia is found in visually impaired children.

With mnemonic dyslexia, the child cannot understand which sound a letter stands for and, accordingly, is unable to master the alphabet. In these cases, dyslexia can be accompanied by delayed mental development.

What conditions lead to dyslexia

In the majority of cases, dyslexia develops as a consequence of prenatal organic damage to the central nervous system following hypoxia, infectious disease, or toxic exposure. Occasionally, dyslexia is caused by genetics or hereditary factors.

Studies of nerve reflexes, hearing, vision, and electroencephalogram recordings in children with dyslexia do not usually show gross abnormalities. However, some changes in the neurological status indicate a delay in motor, mental and intellectual development of dyslexic children. For example, insufficient precision or differentiation of movements in conscious activities can be noted in them. The child's motor skills may be somewhat inappropriate for his or her age, although during games and unconscious movements, children do not differ from their peers.

Electroencephalograms in dyslexic children also show slightly delayed brain maturation with normal hearing acuity. However, visual function, which has been studied recently, has its own peculiarities in some children with dyslexia. Normally, the receptors in the two eyes are different and transmit different pictures to the brain. The brain independently decides which group of receptors in a particular eye to send the image to. In dyslexic children, the image perception areas of both eyes are the same and if the signals from both eyes reach the perception area at the same time, the brain cannot "decide" which image is to be mirrored. This explains the difficulty in quickly recognizing letters and syllables.

Dyslexia can also occur in adults. More often this disorder is identified after craniocerebral trauma or stroke (impaired cerebral circulation). In both cases, areas of the cerebral cortex are affected.
Dyslexia, as well as aphasia (impaired speech function) is a common symptom in patients with left hemispheric stroke.
In addition to dyslexia, these patients may also have depressive disorders, anxious moods and problems with purposeful movement.

Dyslexic phenomena may accompany the development of a large-scale tumor in the left hemisphere of the brain. Patients report headaches, dizziness, memory loss, vision loss, and difficulty finding words.

What doctors to visit when you have dyslexia

Dyslexia is a condition that requires a comprehensive approach, so the decision of which doctor to consult when you have dyslexia symptoms depends on the age of the patient and previous events.

Children with reading problems require consultation with a pediatrician, neurologist, psychologist, and speech therapist.

If text recognition worsened suddenly, after an acute disturbance of cerebral circulation, the patient is consulted by a neurologist and a speech therapist. If memory, reading and speech problems gradually develop, it is necessary to see a therapist who may refer the patient to an oncologist or neurosurgeon.

Diagnosis and examinations for dyslexia

Examination of a child with symptoms of dyslexia includes checking the dictation reading and writing skills and comparing them to his age, intellectual development, and logical abilities. A child with dyslexia performs tasks that require the use of speech much worse than tasks that use figurative or intuitive thinking. Graphomotor and motor skills are investigated. A speech therapist is necessarily involved in the diagnostic search, whose tasks are aimed at identifying problems with articulation and phonetics. A neurologist evaluates movement coordination, motor skills, and neurological symptoms. In some cases, it is necessary to resort to electroencephalography, the results of which can be used for early diagnosis of some forms of dyslexia.