Swallowing function in patients with spinal muscular atrophy before and after the introduction of new gene-based therapies: what has changed?

Abstract

Objective: Individuals diagnosed with Spinal Muscular Atrophy (SMA), particularly those presenting with the most severe phenotypes, have long contended with significant swallowing dysfunction. The recent emergence of efficacious advanced therapy has fundamentally altered the landscape of SMA management. By encompassing both the pre and post gene-based therapy eras within our analysis, we endeavour to elucidate the potential impact of these novel therapeutic interventions on this function.

Methods: Following the established methodology outlined by the Joanna Briggs Institute, a scoping review was conducted. This review encompassed relevant literature published up to March 2024. Two electronic databases were searched, with additional studies identified by reviewing reference lists of pertinent articles. The search strategy employed a combination of keywords including "spinal muscular atrophy", "SMA", "swallowing", "feeding", and "nutrition". Articles were initially screened based on title and abstract, followed by a full-text review of eligible studies published in peer-reviewed English language journals.

Results: The initial database search resulted in 462 articles, from which 23 studies were ultimately selected for analysis. Pre gene-based therapy studies revealed swallowing dysfunction as a prominent feature. Patients frequently reported challenges with chewing, choking on solids and liquids, and abnormal tongue movements during eating. Early dysphagia research relied on subjective measures (questionnaires, scales). objective measures like video fluoroscopic (VFSS) were rare. After gene-based therapies (GBTs), VFSS became the dominant, more objective method. Studies investigating the post-gene therapy era suggest potential clinical benefits, with trends towards improvement or stabilization of swallowing function.

Conclusion: Pre gene-based therapy studies revealed widespread swallowing dysfunction in SMA. Conversely, the post-treatment era suggests potential improvement. Future research should prioritize identifying optimal therapies for individual swallowing function and develop validated assessments to optimize SMA management.