Computer analysis of the EEG as an aid in the evaluation of dietetic treatment in phenylketonuria.

The effect on the EEG of the reintroduction of phenylalanine in the diet of 6 patients with PKU on treatment was studied. Patients received daily loads of 100 or 150 mg L-phenylalanine/kg, equally divided over the meals, and computerized spectral EEG analysis was performed. The following EEG changes were seen: (1) occurrence of activity in the low frequency band (2--5 c/sec), (2) change of frequency of dominant rhythms; (3) change in the degree of synchrony between identical frequencies, occurring in different derivations. EEG changes increased quantitatively parallel to increasing blood phenylalanine and reversed after stopping the phenylalanine administration, suggesting that the EEG abnormalities are a measure for the degree of intoxication caused by phenylalanine or its metabolites. It is suggested that the EEG data may be useful deciding to terminate the diet in PKU.