Mucopolysaccharidoses type I and II: new neuroimaging findings in the cerebellum

Background: The neuroimaging literature on mucopolysaccharidoses (MPS) is focusing mostly on supratentorial findings. Our study aims to extend the spectrum of neuroimaging findings in patients with MPS focusing on the cerebellum.

Methods: Twelve patients were included (7 MPS type I and 5 MPS type II). The median age at last MRI was 9.9 years (mean age 10.1 years, range 1.8-28.8 years). All available brain MR images were retrospectively evaluated for infratentorial and supratentorial abnormalities with semiquantitative analysis and qualitative evaluation.

Results: Infratentorial findings included enlarged perivascular spaces (PVS) in the cerebellum in 7/12, mega cisterna magna in 3/12 and macrocerebellum in 2/12 patients. Enlarged cerebellar PVS developed later than those in the supratentorial brain and showed mild changes in size over time. The macrocerebellum developed progressively and seems to be caused by a thickening of the cortical cerebellar gray matter. Enlarged PVS in the brain stem were found in 10/12 patients. Supratentorial findings included enlarged PVS in all patients. Ventriculomegaly and white matter signal abnormalities were noted in 8/12, cerebral atrophy in 7/12 patients.

Conclusion: Involvement of the posterior fossa structures in MPS I and II is not uncommon. Our study revealed two neuroimaging findings that have not been previously described in MPS: enlarged PVS in the cerebellum and a macrocerebellum. The pathogenesis and clinical significance of these new findings remain unclear and should be assessed in a larger cohort of patients.