Correlation between cerebral MRI abnormalities and mental retardation in patients with mucopolysaccharidoses.

Mucopolysaccharidoses (MPSs) are a group of inherited disorders due to lysosomal enzyme deficiencies which lead to multi-organ accumulation of glycosaminoglycans. Some forms of MPS disorders are characterized by various degrees of mental retardation. Magnetic Resonance Imaging (MRI) is the primary imaging technique to detect CNS alterations. The aim of this study is to evaluate the correlation between white matter (WM) alterations and the presence of mental retardation. We analyzed 20 patients with different forms of MPSs, 11 with mental retardation and 9 with a normal cognitive function; all of them underwent brain MRI and received a score on the basis of the alterations (WM alterations; perivascular, subarachnoid, and ventricular space enlargement; abnormalities of the basal ganglia, of the corpus callosum and of the atlanto-axial joint). All patients with mental retardation presented severe WM alterations, while only five out of the nine subjects without mental retardation showed certainly WM abnormalities. As far as the other cerebral abnormalities are concerned, no difference between the two groups has been found. These data seem to show that there is a significant correlation between the presence of WM alterations and mental retardation.