Efficacy of Enzyme Replacement Therapy on the range of motion of the upper and lower extremities in 16 Polish patients with mucopolysaccharidosis type II: A long-term follow-up study

Background: Enzyme replacement therapy (ERT) with idursulfase is available for patients with mucopolysaccharidosis (MPS) type II, and improvements in certain somatic signs and symptoms have been reported. The aim of the study was to assess the effectiveness of ERT with idursulfase (Elaprase (R)) on the passive joint range of motion (JROM) in the upper and lower extremities of patients with MPS II. Methods: The study included 16 Polish patients diagnosed with MPS II and followed in our Institute in the years 2009-2016. The study group was divided for groups of neuronopathic (group 1, n=12) and non-neuronopathic (group 2, n=4) patients. A passive JROM was measured with a goniometer by one physiotherapist, while in group 1 it was assessed at baseline and after both short-term (52 weeks) and long-term (mean 230 weeks, range: 108-332 weeks) ERT. In group 2, it was assessed at baseline and after short-term ERT (68-85 weeks, no data for long-term ERT). Results: In group 1, after 52 weeks of ERT, we observed some improvement of passive ROM in wrist flexion (5/12 patients), shoulder abduction and wrist extension (3/12 patients), shoulder flexion, elbow and knee extension (2/12 patients). After long-term ERT (mean 230 weeks), the improvement in JROM was observed only in 2 patients. There was no improvement in the shoulder abduction, elbow flexion and extension, hip and knee extension. In group 2, the improvement in passive ROM was observed in several joints: shoulder flexion, wrist flexion and extension improved (2/4 patients) and shoulder abduction (1/4 patients). Conclusion: ERT is of low efficacy on correcting the range of motion of joints in MPS II patients.