Upper limb motor function in individuals with SMA type 2: natural history and impact of therapies

• Published in: Journal of neurology Vol. 272; no. 5; p. 331
• Main Authors: Carrera-García, Laura, Expósito-Escudero, Jessica, Ñungo Garzón, Nancy Carolina, Pareja, Ana, Fernández-García, Miguel A., Ortez, Carlos, Medina, Julita, Martínez-Salcedo, Eduardo, Urbano, Mario, Grimalt, Maria Antonia, Munell, Francina, García-Campos, Óscar, Roca, Sandra, Moya, Obdulia, Estévez-Arias, Berta, Balsells, Sol, Frongia, Anna Lia, Borràs, Ariadna, Puig-Ram, Cristina, García Romero, Mar, Calvo, Rocío, López-Lobato, Mercedes, Pitarch-Castellano, Inmaculada, Natera-de Benito, Daniel, Nascimento, Andres
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2025; Springer Nature B.V
• Subjects: Adolescent; Age; Child; Child, Preschool; Children; Disease Progression; Female; Follow-Up Studies; Humans; Infant; Male; Medicine; Medicine & Public Health; Natural history; Neurology; Neuroradiology; Neurosciences; Oligonucleotides; Original Communication; Retrospective Studies; Spinal Muscular Atrophies of Childhood - drug therapy; Spinal Muscular Atrophies of Childhood - physiopathology; Spinal Muscular Atrophies of Childhood - therapy; Spinal muscular atrophy; Upper Extremity - physiopathology; Young Adult; Nusinersen; RULM; Risdiplam; Natural history; Upper limb function; Spinal muscular atrophy
• ISSN: 0340-5354; 1432-1459; 1432-1459
• DOI: 10.1007/s00415-025-13042-y

Objectives To describe the natural history of the upper limb motor function in spinal muscular atrophy (SMA) type 2 and analyze the impact of SMA-modifying therapies on Revised Upper Limb Module (RULM) scores. Methods This is a retrospective, multicenter, observational study including individuals with SMA type 2, aged between 30 months and 20 years at the time of their first RULM assessment, with available follow-up data. Results We enrolled 149 untreated individuals as part of the natural history cohort, with a mean age of 9.5 years at the first assessment and a mean follow-up duration of 3.98 years (SD 1.97, range 0.3–7.7). An increase in RULM scores was observed in early childhood within this cohort. However, after 4.4 years of age, a gradual decline in RULM scores was noted with increasing age. In contrast, RULM scores were significantly higher in individuals receiving treatment with nusinersen or risdiplam compared to natural history data. Conclusion Our findings provide a natural history of upper extremity motor function in children and adolescents with SMA type 2. The RULM scores typically improve during the early years of life, peaking around 4.4 years of age, after which they progressively decline with age. The data presented here will facilitate the assessment of treatment response in individuals with SMA type 2, especially in those with already severely limited motor function.