Minor neurological dysfunction in children with dyslexia

AIM To improve understanding of brain function in children with severe dyslexia in terms of minor neurological dysfunctions (MNDs).

METHOD One hundred and four children (81 males, 23 females; age range 7-12y; mean age 9y 7mo, SD 1y 2mo;) with severe dyslexia (the presence of a Full-scale IQ score of 85, retardation in single-word or text reading of >= 2y), assessed in a department of dyslexia of a third-level regional psychiatric centre, underwent a neurological examination according to Touwen and a multidisciplinary child psychiatric assessment. Special attention was paid to severity and type of MND. Data were compared with neurological morbidity data of children in the general population.

RESULTS Most children had MND (87%): 43% had simple MND, 44% complex MND. The incidence of MND was significantly higher(p <0.001) in the children with dyslexia than in the general population (simple MND 15%, complex MND 6%). Children with dyslexia showed especially fine manipulative disability and - to a lesser extent - mild dysfunction in muscle tone regulation and excessive presence of associated movements. A comorbid psychiatric syndrome was diagnosed in 66 children (63%): emotional disturbances (27%), adjustment disorder (42%), hyperkinetic disorder (15%), autism spectrum disorder (3%), specific disturbances of childhood not otherwise specified (13%). The neurological findings of children with dyslexia with and without psychiatric comorbidity were similar.

INTERPRETATION Our results demonstrate the importance of neurological and child psychiatric assessment in children with severe dyslexia. Our findings suggest that dysfunction of cortical structures plays a dominant role in dyslexia.