In an eleven-year-old boy with left-sided epileptic paroxysms fromthe age of one year examination by magneticresonance (MRI)revealed an extensive encephalomatic cyst in the dorsal part of the right parietal lobe.MRIexamination confirmed also the presence of a non-corrected transposition of the large arteries with a defect of theventricular septum after balloon atrioseptostomy at the age of 4 months and Senning 's intraatrial surgicalredirection at the age of one year.The authors used the method of sequential segmental analysis for evaluation ofthe atrioventricular and atrioarterial connection in the complicated congenital cardiac defect.They recommendMRI examination for the postoperative follow up of child patients at risk.