Neurophysiological, psychological, and nutritional investigations during discontinuation of the phenylalanine-restricted diet in children with classic phenylketonuria.

Assessment of cortical sensory and psychological functions in children with classic phenylketonuria during the time period of diet discontinuation did not uncover any significant changes when pre-diet and post-diet termination data were compared. Analysis of relationships among the study variables found that children who had adequate dietary control and who were of average or above average intelligence displayed normal somatosensory evoked potentials (SEP) whereas those children with less adequate dietary control and lower IQ scores had atypical SEP waveforms.