Evaluation of Blood Brain Barrier Integrity and Structural Abnormalities in MPS IIIB Patients Using Multimodal Magnetic Resonance Imaging

Inclusion Criteria: * Subject and/or subject's parent or legal guardian provides informed consent * Subject is ≥5 years of age. * Subject has a definitive diagnosis of MPS IIIB, as determined by either a documented deficiency in alpha-N-acetylglucosaminidase (NAGLU) enzyme activity or documented functionally-relevant mutations in both alleles of the NAGLU gene. Exclusion Criteria: * The subject has any internal or non-removable external metal items that may present a safety risk (for MRI), or any other medical condition or circumstance in which an MRI is contraindicated. * The subject has a known or suspected hypersensitivity to anaesthesia, a bleeding disorder, or any other medical condition or circumstance in which a lumbar puncture (for collection of CSF) is contraindicated. * Previous allergic reaction to gadolinium-based MRI contrast media.