Purpose or Case Report: Enzyme replacement therapy (ERT) is approved for the treatment of mucopolysaccharidoses (MPS) I: Hurler syndrome (IH), Hurler-Scheie syndrome (IHS) and Scheie syndrome (IS), II: Hunter syndrome, and VI: Maroteaux-Lamy syndrome. However, ERT is thought to have no therapeutic effect on the central nervous system (CNS) because the enzyme could not permeate through the blood-brain barrier (BBB). We aimed to assess CNS involvement in MPS at the start of ERT and to evaluate the interval changes demonstrated on magnetic resonance imaging (MRI) over a long-term follow up.
Methods & Materials: Cranial MRIs were carried out in 17 patients with MPS (11 with type II, three with type IH, two with IS and one with type VI). The clinical phenotypes were judged as moderate (n=13) and severe (n=4). All of the patients had multiple MRI examinations. The images were assessed using a 3-point scale on five MRI findings by two pediatric radiologists as follows: 1) perivascular space (PVS) enlargement, 2) white matter signal abnormality (WMA), 3) abnormal signal of thalamus, 4) ventriculomegaly, and 5) cerebral cortical atrophy.
Results: The total point of MR finding were much higher in the severe phenotype group (mean, 12.2 points) than that in the moderate group (mean, 6.4 points) on initial examinations. All severe phenotype patients had both ventriculomegaly and cortical atrophy. Follow-up MRI after ERT showed that 65% patients (n=11) were categorized as improvement (n=7) or unchanged (n=4) and the others were progressive (n=6). However, none of the patients had any newly developed abnormal lesions after ERT. All MPS type I patients showed improvement in MRI findings. No improvements in ventriculomegaly and cerebral cortical atrophy were observed in any of the cases.
Conclusions: The spectrums of ventriculomegaly and cerebral cortical atrophy reflect the severity of clinical findings and cranial MRI reveals the effectiveness of ERTs for individual MPS patients.