Neuroradiological (MRI) Abnormalities in Phenylketonuric Subjects: Clinical and Biochemical Correlations

Abstract

A clinical, biochemical and neuroradiological (MRI) study was performed in 22 hyperphenylalaninemic patients detected by neonatal screening and early treated (Group A; 5-23 years old, 13 females and 9 males) and in 5 late detected, symptomatic subjects (Group B; 9-23 years old, 3 females and 2 males). The screening subjects were clustered in a Group A1 (10 on diet patients), and a Group A2 (12 after end of diet patients). On MRI examination (1.5-T magnet, SE T1-weighted 530/22/2, T2-weighted 2400/15-90/1 sequences, SL 6 mm, gap 1.8) a symmetrical increase of the T2-weighted signal in the periventricular white matter was found in all patients. The periatrial white matter was always involved, the occipital region was affected in 22 cases, the frontal region in 16. Concomitant signal decrease on the T1-weighted sequences in the same areas with the highest signal intensity on the T2-weighted scans was found in 7 patients (in 3 out of 12 Group A2 and in 4 out of 5 Group B patients). In 6 Group A and in 3 Group B subjects a variable degree of cortical and subcortical atrophy was detected.

A significantly positive correlation was found between white matter involvement and the degree of recent exposition to high PHE values. This correlation was also confirmed when only Group A was examined. Moreover, a significant difference in neuroradiological involvement was found between Group A1 and Group A2 subjects, but not between Group A2 and Group B subjects.

Our data suggest that the white matter signal abnormalities, as detected by MRI technique, are probably the corollary of the recently sustained exposition to high PHE concentration. A longitudinally designed study needs to clarify the prognostic value of the neuroradiological findings and the nature of their bearing on the clinical status.

Key words

PKU - MRI - White matter abnormalities