Introduction
Nusinersen is associated with an improvement in motor function in children with spinal muscular atrophy (SMA) but data on respiratory muscles strength are scarce. Respiratory muscles performance and lung function were evaluated in children with SMA 1c and 2 after 6 injections of Nusinersen (M14). Results from SMA2 patients were compared to data of age‐matched historical controls. Motor function tests (MFM and HINE‐2) were assessed at baseline and M14 in the treated patients.

Results
Sixteen children (2 SMA type 1c, 14 SMA type 2), mean age 9.4±2.3 years, were included. The data of 14 historical SMA 2 controls (mean age 9.3±1.9 years) were gathered. The strength of the global inspiratory muscles of SMA 2 treated with nusinersen, assessed on maximal static inspiratory pressure, forced vital capacity, and esophageal pressure during a maximal sniff, was significantly better compared to historical controls (p<.05). A significant improvement in MFM and HINE‐2 was observed in the 16 SMA patients treated with nusinersen after 14 months as compared to baseline.

Conclusion
In children with SMA type 2, respiratory muscle performance was significantly better after 6 injections of nusinersen as compared to age‐matched SMA type 2 historical controls.