Brain magnetic resonance imaging findings in patients with mucopolysaccharidosis VI.

Introduction: Mucopolysaccharidosis type VI (MPS VI) is a rare lysosomal storage disorder caused by the deficient activity of N-acetylgalactosamine 4-sulfatase. MPS VI is usually considered as not being associated with mental retardation.

Aims/methods: The main objective of the present study was to describe brain magnetic resonance imaging (MRI) findings and their correlation with clinical and biochemical findings in MPS VI patients. The study was conducted at Hospital de Clínicas de Porto Alegre, Brazil with 25 MPS VI patients. All patients were evaluated through clinical evaluation, IQ tests, urinary glycosaminoglycans (GAG) analysis, and brain MRI.

Results: Mean age at evaluation was 10.6 ± 4.52 years. Five of 16 patients presented total IQ below the normal range. Brain MRI was abnormal in the majority of patients (n = 19/21), and the most frequent abnormalities found were the presence of dilated perivascular spaces and white matter lesions. Correlations were found between age and normalized white matter lesion load (NLL) (r = 0.46; p = 0.04) and normalized cerebral volume (NCV) (r = -0.56; p = 0.01), between NLL and height deficit (r = 0.48; p = 0.04), and between NCV and weight deficit (r = -0.58; p = 0.01) and height deficit (r = -0.55; p = 0.01). A correlation between urinary GAG levels and quantitative brain MRI findings was not found, neither between qualitative and quantitative brain MRI findings and IQ scores.

Conclusions: MPS VI patients may present abnormal IQ scores without correlation with brain abnormalities on the MRI, a finding which was found to be very frequent in MPS VI. Additional studies are required to confirm our findings.