Bulbar function in children with spinal muscular atrophy type 1 treated with nusinersen.

Aim: To describe bulbar function trajectories in patients with spinal muscular atrophy (SMA) type 1 treated with nusinersen in the UK and Italy.

Method: In two previously reported, retrospective, observational cohort studies, we observed the 2-year change in the Children's Eating and Drinking Ability Scale (CEDAS) (the revised and optimized version of the Paediatric Functional Oral Intake Scale [p-FOIS]) and Oral and Swallowing Ability Tool (OrSAT) in 44 patients treated on average at 8.3 months (interquartile range = 4.1-14.4 months), with data collected every 6 months from treatment initiation.

Results: The Italian cohort had more participants in the 1b group (symptom onset >2 weeks and <3 months), while the UK had more participants in the 1c group (symptom onset <6 months). Over 2 years, the p-FOIS/CEDAS captured lack of bulbar improvement in the 1b group, with 40% displaying stability and 45% showing decline; in the 1c group, stability was captured (71%). OrSAT captured improvement in 47% of the 1b group and 43% of the 1c group at 2 years; this was predominantly because of age-related speech acquisition and feeding viscosities, where the item was not age-appropriate at baseline.

Interpretation: The p-FOIS/CEDAS and OrSAT measures capture complementary information on the effect of disease-modifying treatments (DMTs) on bulbar function. Further studies are required to understand bulbar function trajectories in symptomatic and presymptomatic cohorts with SMA receiving different DMTs.