If there are abnormalities in the electrical activity of
the brain, it can indicate the presence of seizure
disorder, the possibility of lesion (depending on the nature of the abnormal electrical activity), etc. But in reality an EEG taps very little, relatively, of the total mass of the brain. Your description indicates that your son's condition is acquired apraxia, not developmental. It would surprise me if the EEG contributes much, if anything, to the knowledge about your son's apraxia.