[Evaluation of brain activation by functional magnetic resonance in offspring of epileptic mothers and their parents in pathogenetic aspects of dyslexia].

Principle: So far, the assessment of cerebral centres activity during fonological awareness test with functional magnetic resonance (fMRI) of families with dyslexia has not been carried out. The up till now published studies concern insignificant number of children or adults with dyslexia, whose results have not been unequivocal.

The Aim: The general aim of the study is the explanation of the pathogenetic mechanisms of dyslexia in offspring of mothers with epilepsy and their family. Detailed aim is the evaluation of the influence of dyslexia occurrence in this particular population on activation of the brain in fMRI during phonological tests.

Material and Method: Before fMRI, all the patients were subjected to classical cerebral MRI to estimate central nervous system structure excluding organic causes of lesions. Finally, the groups subjected to MRI included 7 children with dyslexia, 7 without dyslexia, 7 mothers with dyslexia, 10 women without dyslexia, 4 fathers with dyslexia, 10 fathers without dyslexia and 15 men without dyslexia. The examination was carried out during fonological awareness test. Mean quantities of activated pixels in the areas of interest--prefrontal cortex (1) and Broca's area (2) were compared in the investigated and control groups.

Results: fMRI demonstrated significantly lower activity in both areas in frontal lobe in offspring of epileptic mothers with dyslexia as compared to offspring without dyslexia (p = 0.01, p = 0.02). Activity of Broca's area in epileptic mothers with dyslexia was significantly lower than in women with dyslexia from the control group (p = 0.05). Mothers with epilepsy and dyslexia, whose offspring also had dyslexia, had significantly lower Broca's area activity. The activity of frontal areas of fathers was on fMRI similar to the activity in control groups.

Conclusions: Epilepsy in mothers with coexisting dyslexia has a modifying effect on the activity of cerebral areas in frontal lobes during the fonological awareness test. Lower activity of Broca's area is a fonotypic trait transmitted to offspring with dyslexia.