Carpal tunnel syndrome in mucopolysaccharidosis type I: clinical, surgical and histopathological findings

Introduction: Mucopolysaccharidosis type I is a rare metabolic disorder characterized by the accumulation of glycosaminoglycans, leading to musculoskeletal disorders such as carpal tunnel syndrome. This retrospective cohort study was performed to determine the prevalence and timing of the development of carpal tunnel syndrome, assess the efficacy of surgery on recurrence and the effect of haematopoietic stem cell transplantation in resolving accumulated degradation products. Methods: Thirty-three mucopolysaccharidosis type I patients, born between 2001 and 2023, were included in this study. They received annual screening and treatment at our specialist hospital. Patient demographics, clinical symptoms of carpal tunnel syndrome pre- and post-carpal tunnel release and histopathological sections of the flexor retinaculum were collected. Regression analyses were conducted to assess cumulative risks and determine hazard ratios and survival curves were plotted. Results: Twenty-seven of 33 mucopolysaccharidosis type I patients, with a median age at the latest follow-up of 13 years (IQR 7.7 to 18.3), were diagnosed with carpal tunnel syndrome on electrophysiological tests or ultrasound at a median age of 3.6 years (IQR 2.8 to 5.2). Only a few patients exhibited clinical symptoms. Twenty-one patients underwent carpal tunnel release and 13 patients experienced recurrence. The highest risk of developing carpal tunnel syndrome was within the first 6 years of life. Eight of the 11 patients accumulated degradation products within lysosomes despite successful haematopoietic stem cell transplantation. Conclusions: In this study, 27 mucopolysaccharidosis type I patients were diagnosed with carpal tunnel syndrome, showing a high-risk window from 0 to 6 years of age. Recurrence of carpal tunnel syndrome after carpal tunnel release surgery was common, occurring in 61.9% of patients.