Written on 10-04-2017

There are several types of dyslexia that can affect the child’s ability to spell as well as read.

“Trauma dyslexia” usually occurs after some form of brain trauma or injury to the area of the brain that controls reading and writing. It is rarely seen in today’s school-age population.

A second type of dyslexia is referred to as “primary dyslexia.” This type of dyslexia is a dysfunction of, rather than damage to, the left side of the brain (cerebral cortex) and does not change with age. Individuals with this type are rarely able to read above a fourth-grade level and may struggle with reading, spelling, and writing as adults. Primary dyslexia is passed in family lines through their genes (hereditary). It is found more often in boys than in girls.

A third type of dyslexia is referred to as “secondary” or “developmental dyslexia” and is felt to be caused by hormonal development during the early stages of fetal development. Developmental dyslexia diminishes as the child matures. It is also more common in boys.

Dyslexia may affect several different functions. Visual dyslexia is characterized by number and letter reversals and the inability to write symbols in the correct sequence. Auditory dyslexia involves difficulty with sounds of letters or groups of letters. The sounds are perceived as jumbled or not heard correctly. “Dysgraphia” refers to the child’s difficulty holding and controlling a pencil so that the correct markings can be made on the paper.

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影響孩子的拼寫和閱讀能力的讀寫障礙有幾種不同類型。

第一類是「創傷性讀寫障礙」。這類讀寫障礙在今天的學齡人口中很少見，通常出現於某些形式的腦創傷之後，又或者由於控制讀寫的大腦區域受損所致。

第二類讀寫障礙被稱為「原發性讀寫障礙」。這類型的讀寫障礙源於腦部左側（大腦皮層）有功能障礙，而不是腦部有損傷，並且不隨年齡而改變。 這些孩子很少能夠應付四年級以上程度的閱讀要求，成年後也可能在閱讀、拼寫和寫作上有困難。 原發性讀寫障礙通過基因（遺傳性）在家族中遺傳。相對女孩，更常見於男孩子身上。

第三類讀寫障礙被稱為「繼發性讀寫障礙」或「發展性讀寫障礙」。就現有的認識，這種讀寫障礙與胎兒早期成長時的荷爾蒙發展有關。發展性讀寫障礙的問題會隨著兒童年紀增長減弱，也較常見於男孩。

讀寫障礙可能影響以下幾方面的能力。視覺上的障礙會導致將數字及字母上下左右顛倒，也沒法以正確順序寫出符號；聽覺上的障礙會引致分辨單一或一組字母讀音時出現困難，無法正確聽取聲音，或對接收到的聲音混亂不清；書寫障礙指兒童於握筆及控筆上有困難，因而無法在紙上做正確的標記。