Musculoskeletal health in Hunter disease (MPS II): ERT improves functional outcomes

Musculoskeletal disease is a significant burden for children with Mucopolysaccharide (MPS) disorders. The Pediatric Outcomes Data Collection Instrument (PODCI) is a validated, functional measure of musculoskeletal health in children with disabilities. The goal of this study is to describe the musculoskeletal manifestations of children with MPS II (Hunter syndrome), and their functional response to intravenous enzyme replacement therapy (ERT). Patients with MPS II were prospectively entered into an IRB approved registry. Chart review of physical findings including, shoulder, elbow, hip, knee and ankle range of motion, and need for carpal tunnel release was performed. Radiographs of the spine and pelvis were evaluated in all patients. Serial PODCI exams were administered to all patients. Seven patients, 5 receiving ERT, were included. Four patients had spinal deformities, seven had modest hip disease, and two required carpal tunnel release. PODCI scores were abnormally low in all domains, but significant improvements in PODCI scores were documented with enzyme replacement therapy. Spine and hip deformity are ubiquitous in MPS II, none of which have required surgical intervention, but require long term monitoring. Patients with MPS II should be monitored for carpal tunnel syndrome. Functional improvements are seen, as documented by the PODCI, in children with MPS II on ERT.