Sleep EEG and developmental dysphasia: lack of a consistent relationship with paroxysmal EEG activity during sleep.

In order to clarify the relationship between developmental dysphasia and EEG abnormalities, paroxysmal activities during sleep were studied in a series of 24 children with expressive developmental dysphasia (mean age 8 years) and compared to a control group of 39 children (mean age 9 years). The children of both groups were selected excluding cases with prior history of neurological disease or epilepsy. In the control group, 37 children had normal sleep EEG while 2 children had paroxysmal abnormalities. In the dysphasic group, epileptic abnormalities were observed in 9 cases, rare in 4 cases and frequent in 5 cases (density: 2.5 to 66.2% of total sleep time). Nevertheless, paroxysmal abnormalities did not reach the frequency described in the Landau-Kleffner syndrome, and it is unlikely that EEG abnormalities could have produced dysphasia.