Neurological assessment of 38 late-diagnosed children with classic phenylketonuria

Abstract

Purpose: We investigated the neurological outcome of 38 late-diagnosed phenylketonuria patients with magnetic resonance imaging (MRI), electroencephalography (EEG), visual evoked potentials (VEP), intelligence quotients (IQ) and examined the correlation of these parameters with the age and the plasma phenylalanine levels of patients at diagnosis.Material and Methods: Thirty-eight late-diagnosed classic phenylketonuria patients were enrolled in the study. Plasma phenylalanine levels were measured by spectrofluorometric method. MRI was evaluated by a pediatric neuroradiologist. Ankara developmental screening inventory (ADSI) and Wechsler intelligence scale for Turkish children (WISC-R) test were performed to detect IQ scores. Porteus Mazo test adapted for Turkish children intelligence test were performed to all children. The EEG of all patients were recorded. VEP was used to measure the electrical activity in the brain to visual stimulus. Results: The high plasma phenylalanine levels and late-diagnosis were associated with low IQ scores, pathological EEG, and pathological VEP patterns. High PA levels were also associated with more serious white matter signal abnormalities. Conclusion: Our results demonstrated the impact of early diagnosis and low levels of phenylalanine at diagnosis on the intellectual, neurological development and visual outcomes.